Document:

<PAGE>

                                                                   EXHIBIT 10.21

7 July 1993

Mr. Alain Cohen
MIL 3
3400 International Dr.,
Suite 4L
N.W., Washington D.C.  20008

Subject:  Letter Agreement on Administration of Building Common Areas

In connection with the Agreement of lease between INTELSAT and MIL 3, Inc.
(INTEL-L-1433) dated 16 June 1993, INTELSAT ("Landlord") and MIL 3 ("Tenant")
hereby agree to the terms of this letter agreement which further clarify the
Lease and Building Rules and Regulations.  The Landlord hereby agrees to make
appropriate adjustments within its procedures to adhere to the following
clarifications:

4.  Signage:

The Landlord shall develop uniform building signage standards for all Multi-
Tenant common areas which shall include directory locations, suite numbers and
proprietary signage at suite entrances, on glass, doors or adjacent vicinity
within the pod floor.  No signage shall be installed without prior written
consent of Landlord.  (INTELSAT is currently working with an outside vendor to
assist in developing signage standards and will convey the results to the Tenant
no later that 31 August 1993.)

6.  Art work:

No tenant art work shall be installed within the Multi-Tenant common areas
without prior written consent of Landlord, who shall first obtain the consent of
all affected parties.  The Landlord shall bear no liability for any such art
work.

10.  Quiet Enjoyment:

The Landlord agrees to protect the Tenant's quiet enjoyment of the demised
premises in a commercially reasonable fashion and if the Landlord permits
receptions to be held within the building areas adjacent to the Tenant's
premises, Landlord shall (1) provide five (5) days advance notice of the
reception, unless Landlord itself has less than five (5) days notice, in which
case, Landlord shall notify tenant as soon as reasonably possible, (2) prevent
the placement of obstacles in front of the double doors leading to the atrium
adjacent to Pod 4L to maintain a minimum safe clearance of five (5) feet, and
(3) prevent the placement of wires and/or cabling
<PAGE>

by suite entrances or by the double doors leading to the atrium adjacent to Pod
4L which do not protect the safety of the building occupants.

40. (of the lease) Reporting of Payments:

With regard to the Reporting of Payments clause, INTELSAT has concluded that the
requirement for a certification by MIL 3's auditors under the Reporting of
Payments clause does not apply as it is INTELSAT's view that the net value of
this contract falls below the $500,000 threshold.

If you are in agreement with the above clarifications please sign below as an
acknowledgement and return to me.

Sincerely,

/s/ Robert A. Lambert
-----------------------------------------
Robert A. Lambert
Department Manager,
Facilities Management and Office Services

Acknowledgement:     /s/ Alain Cohen      Date:   7/16/93
                  ------------------            ---------

                  MIL 3 ( or designated representative)

cc:  C. Lewis
     D. Meltzer
     Mil 3 Lease file
<PAGE>

                                                                   5 August 1993

Mr. Alain Cohen
MIL 3, Inc.
3400 International Dr., N.W.
Suite 4L
Washington D.C.  20008

Dear Alain:

     Attached for your files is a fully signed original of INTEL-L-1433 and a
copy of the signed letter agreement, dated 7 July 1993.

     All rental payments and inquiries should be directed to Tuula Sumpter,
Shannon & Luchs Polinger, at (202) 944-8235.  If you have any questions
regarding the Lease, please feel free to contact me.

                              Sincerely,

                              /s/ Cecilia R. Lewis
                              ------------------------------
                              Cecilia R. Lewis
                              Special Projects Administrator

Attachment

cc:  K. Gross/MIL 3, Inc.
     R. Lambert  w/o attachment
     D. Meltzer  w/o attachment
     file
<PAGE>

                                                                    INTEL-L-1433

                               AGREEMENT OF LEASE

                                    BETWEEN

                        INTERNATIONAL TELECOMMUNICATIONS

                             SATELLITE ORGANIZATION

                                      AND

                                   MIL 3, INC

                                                             DATE:  18 June 1993
<PAGE>

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
Article No.    Title                                            Page
-----------    -----                                            ----
<S>            <C>                                              <C>
     1.        DEMISED PREMISES...............................     1

     2.        TERM...........................................     2

     3.        USE............................................     3

     4.        RENTAL.........................................     4

     5.        RENTAL ESCALATION..............................     8

     6.        SECURITY DEPOSIT...............................    10

     7.        PREOCCUPANCY WORK AGREEMENT....................    10

     8.        ASSIGNMENT AND SUBLETTING......................    11

     9.        CLEANING AND MAINTENANCE BY TENANT.............    13

     10.       ALTERATIONS....................................    13

     11.       SIGNS AND FURNISHINGS..........................    14

     12.       ENTRY FOR HOUSEKEEPING, REPAIRS AND INSPECTIONS    15

     13.       INSURANCE RATING...............................    15

     14.       TENANT'S EQUIPMENT.............................    16

     15.       INDEMNITY AND PUBLIC LIABILITY INSURANCE.......    17

     16.       SERVICES AND UTILITIES.........................    18

     17.       METERED UTILITIES..............................    22

     18.       RESPONSIBILITY FOR DAMAGE TO DEMISED PREMISES..    23

     19.       LIABILITY FOR DAMAGE TO PERSONAL PROPERTY AND
               PERSONS........................................    23

     20.       FIRE AND OTHER CASUALTY DAMAGE TO DEMISED
               PREMISES.......................................    24

</TABLE>
                                      -i-
<PAGE>

<TABLE>
<CAPTION>
Article No.    Title                                            Page
-----------    -----                                            ----
<S>            <C>                                              <C>
     21.       BANKRUPTCY OR INSOLVENCY.......................    25

     22.       DEFAULT OF TENANT..............................    28

     23.       WAIVER.........................................    31

     24.       FIRST MORTGAGE.................................    31

     25.       ATTORNMENT.....................................    32

     26.       CONDEMNATION...................................    32

     27.       RULES AND REGULATIONS..........................    33

     28.       RIGHT OF LANDLORD TO CURE TENANT'S DEFAULT;
               LATE PAYMENTS..................................    33

     29.       NO PARTNERSHIP.................................    34

     30.       NO REPRESENTATIONS BY LANDLORD.................    34

     31.       BROKERS........................................    34

     32.       NOTICES........................................    35

     33.       ESTOPPEL CERTIFICATES..........................    35

     34.       COVENANTS OF LANDLORD..........................    36

     35.       SURRENDER OF DEMISED PREMISES..................    36

     36.       HOLDING OVER...................................    37

     37.       LIEN FOR RENT..................................    37

     38.       UNDERLYING LEASE...............................    37

     39.       SALES AND EXCISE TAXES.........................    38

     40.       REPORTING OF PAYMENTS..........................    38

     41.       GENDER.........................................    39

     42.       BENEFIT AND BURDEN.............................    39

</TABLE>
-ii-
<PAGE>

<TABLE>
<CAPTION>
Article No.    Title                                            Page
-----------    -----                                            ----
<S>            <C>                                              <C>
     43.       GOVERNING LAW..................................    39

     44.       WAIVER OF TRIAL BY JURY........................    39

     45.       OPTION TO LEASE ADDITIONAL OFFICE SPACE........    39

     46.       PARKING OPTION.................................    40

     47.       MISCELLANEOUS..................................    40

     48.       ENTIRE AGREEMENT...............................    41

Exhibit A      Plan of Demised Premises                           1A

Exhibit B      Preoccupancy Work                                  1B

Exhibit C      Rules and Regulations                              1C

Exhibit D      Plan of Phase I of the Office Building             1D

Exhibit E      Letter of 17 December 1992                         1E

</TABLE>

                                     -iii-
<PAGE>

                                     LEASE
                                     -----

     THIS LEASE number INTEL-L-1433 is made and entered into this 18th day of
June, 1993, by and between the International Telecommunications Satellite
Organization ("Landlord") and MIL 3, Inc. ("Tenant").

     In consideration of the agreements hereinafter set forth, the parties
hereto mutually agree as follows:

1.   DEMISED PREMISES
     ----------------

     Landlord hereby leases to Tenant, and Tenant hereby leases from Landlord,
four (4) separate areas of office space (the "demised premises"), outlined on
Exhibit A attached hereto, located on the second and fourth levels of Pod L of
Phase II of the office building situated at 3400 International Drive, N.W.,
Washington, D.C. 20008-3098.  All references in this lease to the "Building"
shall mean only Phase II of the office building, a plan of which is provided in
Exhibit D attached hereto.  The demised premises constitute a total of 7,172
square feet of rentable area, which includes a proportionate share of the common
areas of Pod L as well as a proportionate share of the common areas of the
Building.  The four separate areas of office space constituting the demised
premises have been measured by Landlord to be 1,441 and 1,261 square feet of
rentable area in Pod 4L; and 2,151 and 2,319 square feet of rentable area in Pod
2L.  The rentable area calculation consists of the net useable area of office
space (NU) plus the proportionate share of common corridor areas within a pod
floor (P), multiplied by the proportionate share of the common areas of the
Building (Core Factor)(1.08) (i.e., [NU + P] x 1.08).  Tenant shall have the
right, at its sole expense, to measure one or more of the spaces after
construction is completed to verify Landlord's measurements.  If Tenant's
measurements (based on the most recent version of the Washington Board of
Realtor's Standard Method of Measurement) reveals a discrepancy of more than 1%
between the rentable area provided in this Lease and the rentable area based on
said measurement, the parties agree to amend the terms of this Lease to conform
to the actual measurement.  Tenant hereby agrees that Landlord shall have the
right, for the purposes of accommodating other tenants of Pod L or otherwise, to
increase or decrease the dimensions, change the configuration, or to otherwise
alter the common corridors;
<PAGE>

however, any such alteration of the common areas shall not increase or decrease
the amount of common area attributable to Tenant as specified in this Article.

2.  TERM
    ----

    A.  The term of this Lease (hereinafter referred to as the "term") shall be
    for a period of five (5) years commencing on the date (the "Lease
    Commencement Date") which corresponds to the later of (a) the date that
    Landlord notifies Tenant that Landlord's Work (as set forth in Exhibit B of
    this Lease) is substantially complete and the demised premises are available
    for occupancy by Tenant (which notification shall be given on or about 15
    April 1993) or (b) three (3) business days following execution of this lease
    by both parties. The term shall expire at midnight on the date (the "Lease
    Expiration Date") which is five (5) years after the Lease Commencement Date.

    B.  Option to Renew
        ---------------

          Tenant shall have and is hereby granted the option to renew or extend
     the term of this Lease for an additional period of five (5) years (the
     "Renewal Period").  Subject to the provisions of paragraph C of this
     Article, the renewal option shall be exercisable by Tenant giving written
     notice to Landlord of the exercise of such renewal option at least six (6)
     months prior to the expiration of the initial term of this Lease.  The
     Renewal Period shall be upon the same terms, covenants and conditions as
     set forth herein with respect to the initial term of this Lease, except
     that (i) the fixed monthly rental payable pursuant to Article 4 during such
     Renewal Period shall be equal to the greater of (a) the fixed monthly
     rental payable hereunder during the Lease Adjustment Year (hereafter
     defined) immediately prior to the commencement of such Renewal Period, or
     (b) the market rate of fixed monthly rental for comparable office space in
     the area prevailing at the commencement of such Renewal Period; provided,
     however, that the fixed monthly rental payable for the first year of the
     Renewal Period shall not exceed by more than 3% the fixed monthly rental
     payable by Tenant during the last Lease Adjustment Year of the initial
     term.  Thereafter, the fixed monthly rental may be adjusted annually at 30%
     of the increase in the Consumer Price Index; however, each year's increase
     shall not exceed 3% of the fixed monthly rental for the previous Lease
     Adjustment Year.  All references in

                                      -2-
<PAGE>

     this Lease to the term hereof shall be construed to mean the initial term
     and such Renewal Period, unless the context clearly indicates another
     meaning is intended.

     C.  Conditions of Exercise of Option to Renew
         -----------------------------------------

          The renewal option referred to in paragraph B of this Article may not
     be exercised by Tenant if, at the time specified in paragraph B for
     exercising such option, (i) this Lease shall not be in full force and
     effect, (ii) Tenant shall not be in possession of the demised premises, or
     (iii) an Event of Bankruptcy (as defined in Article 21) or an event of
     default (as defined in Article 22) shall have occurred and shall be
     continuing.  If Tenant shall fail to exercise the renewal option granted
     hereunder during the time or in the manner provided in paragraph B for the
     exercise thereof, or if at the time specified for the exercise of such
     renewal option, Tenant shall not be entitled to exercise such option
     because of the provisions of this paragraph C, then and in any such event,
     such renewal option shall be absolutely void and of no force and effect.

3.  USE
    ---

    Tenant shall use and occupy the demised premises solely for office use in
accordance with applicable regulations, and for no other purpose; provided,
however, that Tenant may use the demised premises for the production and sales
of computer software and documentation.  Tenant will not use or occupy the
demised premises for any unlawful, disorderly, or hazardous purpose, and will
comply with all present and future laws, ordinances, regulations and orders of
all governmental authorities having jurisdiction over the demised premises.
Tenant will not suffer any act to be done or any condition to exist on the
demised premises which may interfere unreasonably with the use of any other
property or improvements within the International Center.  Notwithstanding
anything to the contrary, Tenant may bring and keep ordinary office supplies
within the demised premises.

                                      -3-
<PAGE>

4.  RENTAL
    ------

    A.  Fixed Monthly Rental
        --------------------

    Tenant shall pay to Landlord a fixed monthly rental of Five Thousand Four
Hundred and One Dollars ($5,401.00) for the office spaces located in Pod 2L and
Five Thousand and Forty Four Dollars ($5,044.00) for the office spaces located
in Pod 4L due and payable in advance on the first (1st) day of each and every
calendar month during the term of this Lease and any renewals of such term
pursuant to Article 2; however, the fixed monthly rental for the first full
month of the first lease year (exclusive of the abatement for this month) shall
be due and payable upon execution of this Lease.

Landlord shall abate fifty percent (50%) of the fixed monthly rental for each of
the first twelve (12) months of the first lease year.

    B.  Operating Costs
        ----------------

        (1) In addition to the fixed monthly rental set forth in paragraph A
        above, Tenant shall pay to Landlord throughout the term of this Lease,
        as additional rental, two percent (2%) (being the approximate and agreed
        upon proportion which the floor area of the demised premises [7,172]
        bears to the architectural and engineering (A&E) design figure for total
        area of the Building [296,733]) of the Actual Operating Expenses. Tenant
        shall receive an annual credit in the amount of $300 to be applied
        toward payment of Operating Expenses.

        (2) The Projected Operating Expenses are estimated to be Four Dollars
        and Fifty Cents ($4.50) per square foot of total area of the Building
        for 1993.

        (3) Upon the Lease Commencement Date, and thereafter at the beginning of
        each calendar year during the term of this Lease, Landlord shall provide
        Tenant with a statement showing Landlord's Projected Operating Expenses
        for such calendar year. Tenant's proportionate share of the Projected
        Operating Expenses shall be due and payable, in equal monthly
        installments, in advance, on the first (1st) day of each and every
        calendar month of such year.

                                      -4-
<PAGE>

        (4) Within the period of ninety (90) days (or as soon thereafter as
        possible) after the close of each calendar year during the term of this
        Lease, Landlord shall give Tenant a statement of such year's Actual
        Operating Expenses and a comparison of same with the Projected Operating
        Expenses. Tenant's proportionate share of the amount by which the Actual
        Operating Expenses for such year exceeds the Projected Operating
        Expenses for such year shall be due and payable by Tenant within thirty
        (30) days of receipt of said statement. If any year-end statement
        provided by Landlord to Tenant pursuant to this paragraph shows that the
        Actual Operating Expenses during the year covered by that statement was
        less than the Projected Operating Expenses on which monthly payments
        were made for that year, Tenant's proportionate share of the
        overpayments for that year may be deducted by Tenant from its next
        payment or payments of fixed monthly rental. Any such overpayments by
        Tenant during the last calendar year of the term of this Lease shall be
        refunded within ninety (90) days after the close of such calendar year,
        unless an event of default shall have occurred and shall be continuing.

        (5) "Actual Operating Expenses", as that term is used herein, shall
        consist of all operating expenses of the Building. Actual Operating
        Expenses shall be computed on the accrual basis and shall include all
        expenditures to maintain all facilities in operation of the Building and
        such additional facilities in subsequent years as may be reasonably
        determined by Landlord to be necessary. Actual Operating Expenses shall
        mean all expenses, costs and disbursements (but not replacement of
        capital investment items or specific costs especially billed to and paid
        by specific tenants or any fines and penalties imposed upon Landlord or
        its agents, except if incurred by Landlord as a result of an act or
        omission of Tenant) of every kind and nature which Landlord shall pay or
        become obligated to pay because of or in connection with the ownership
        and operation of the Building, including but not limited to, the
        following:

            (a) Wages and salaries of all employees engaged in the operation,
            maintenance, housekeeping, or security of the Building and grounds,
            including payroll, taxes, insurance and benefits relating thereto.

                                      -5-
<PAGE>

            (b) All supplies and materials used in the operation, maintenance,
            housekeeping, and security of the Building and grounds.

            (c) Cost of all utilities including surcharges for the Building and
            the cost of water, sewer, power, heating, lighting, air conditioning
            and ventilation for the Building.

            (d) Cost of all maintenance, housekeeping, and service agreements
            for the grounds, the Building and the equipment therein, including
            but not limited to, security and energy management services, window
            cleaning, snow removal, elevator maintenance, and janitorial
            service.

            (e) Cost of all insurance relating to the Building and grounds,
            including the cost of casualty and liability insurance applicable to
            the Building and grounds, and Landlord's personal property used in
            connection therewith.

            (f) Cost of repairs and general maintenance (excluding repairs and
            general maintenance paid by proceeds of insurance or by Tenant or
            other third parties, and alterations attributable solely to tenants
            of the Building other than Tenant).

            (g) Management fees for the management of the Building.

            (h) The costs of any additional services not provided to the
            Building or grounds at the Lease Commencement Date but thereafter
            provided by Landlord in the prudent management of the Building as a
            whole.

            (i) The cost of any capital improvements made to the Building or
            grounds after the Lease Commencement Date that reduce other
            operating expenses or are required under any governmental law or
            regulation that was not applicable to the Building or grounds at the
            time it was constructed, such cost thereof to be amortized over such
            reasonable period as Landlord shall determine in accordance with
            Generally Accepted Accounting Principles

                                      -6-
<PAGE>

            (GAAP) together with interest on the unamortized balance at the rate
            of 10% per annum.

            (j) Property taxes imposed upon the demised premises by the District
            of Columbia or the Government of the United States, but only to the
            extent the rate of such taxes exceeds $2.15 for each $100 of
            assessed market value.

        (6) Operating Expenses shall be "net" only, and for that purpose shall
        be reduced by the amounts of any reimbursement, refund or credit
        received or receivable by Landlord with respect to any item of cost that
        is included in operating expenses. The following items shall be excluded
        from the definition of operating expenses as used herein:

            (a) Interest on debt or amortization payments on any mortgage or
            rental under any ground lease or other underlying lease;

            (b) Any real estate brokerage commissions or other cost incurred in
            procuring other tenants;

            (c) Any advertising expenses;

            (d) Salaries of officers and employees of Landlord to the extent not
            engaged in the management of the Building;

            (e) The cost of any items for which Landlord is reimbursed by
            insurance or otherwise; and

            (f) The cost of any repairs, alterations, improvements or other
            items which are made in order to prepare for a new tenant's
            occupancy.

        (7) Tenant at its expense shall have the right at all reasonable times
        to audit Landlord's books and records relating to Actual Operating
        Expenses under this Lease for any year or years for which additional
        rental payments pursuant to this

                                      -7-
<PAGE>

        paragraph B become due; or at Landlord's sole discretion Landlord will
        provide such audit prepared by an independent certified public
        accountant.

        (8) Tenant's obligation for amounts set forth herein shall survive the
        termination or expiration of this Lease, provided that said amounts were
        incurred before the date of expiration or termination.

    C.  Tenant shall pay all rental without demand, deduction, setoff or
    counterclaim, by check to such party and address as Landlord may designate
    by written notice to Tenant. If Landlord shall at any time or times accept
    said rental after it shall become due and payable, such acceptance shall not
    excuse delay upon subsequent occasions, or constitute a waiver of any or all
    of Landlord's rights hereunder. If the Lease Commencement Date occurs on a
    day other than the first day of a calendar month, or the lease term ends on
    a day other than the last day of a calendar month, the fixed monthly rental,
    for the partial month(s), shall be appropriately prorated at the rate of
    one-thirtieth (1/30th) of said fixed monthly rental for each day of such
    partial months during which this Lease is in effect. If the Lease
    Commencement Date occurs on a day other than the first day of a calendar
    month, the prorated fixed monthly rental for the first partial month shall
    be payable in advance on the Lease Commencement Date. If the Lease
    Commencement Date occurs on a day other than the first day of a calendar
    year, or the lease term ends on a day other than the last day of a calendar
    year, the additional rental for increases in operating costs, for the
    partial year(s), shall be appropriately prorated at the rate of one-three
    hundred and sixty fifth (1/365th) of said additional rental for each day of
    such partial years during which this Lease is in effect.

5.  RENTAL ESCALATION
    -----------------

    The fixed monthly rental shall be adjusted (but not decreased) for each
calendar year of the term, commencing on January 1, 1994 and on January 1 for
each succeeding calendar year (the "Adjustment Year"), on the following terms
and conditions: The fixed monthly rental for each Adjustment Year shall be the
sum of (i) the fixed monthly rental for the prior calendar year and (ii) thirty
percent of the product of the fixed monthly rental for the prior calendar year
and a fraction, the numerator of which shall be the difference (but not less
than zero) between (a) the

                                      -8-
<PAGE>

Consumer Price Index for All Urban Consumers, All Items, Washington, D.C.
Metropolitan Area, Base 1982-84=100, issued by the Bureau of Labor Statistics of
the U.S. Department of Labor (hereinafter referred to as the "Consumer Price
Index") for November prior to the first day of such Lease Adjustment Year and
(b) the Consumer Price Index for November prior to the commencement of the prior
calendar year and the denominator of which shall be the Consumer Price Index for
the November prior to the commencement of the prior calendar year; provided,
however, that each year's increase in fixed monthly rental based upon the
Consumer Price Index shall not exceed 3% of the fixed monthly rental for the
previous Lease Adjustment Year; provided, however, that the fixed monthly rental
for the 1994 calendar year shall be the sum of the fixed monthly rental for the
1993 calendar year and fifty percent (50%) of item (ii) above. With the first
payment of fixed monthly rental during a Lease Adjustment Year which is due at
least fifteen (15) days after Tenant's receipt of a statement (the "Escalation
Statement") from Landlord specifying the fixed monthly rental payable during
such Lease Adjustment Year (computed as aforesaid), Tenant shall pay the fixed
monthly rental specified therein for such month and, in addition, shall pay the
difference for all prior months of such Lease Adjustment Year between the fixed
monthly rental so specified and the fixed monthly rental which Tenant was
theretofore required to pay for such prior months. Thereafter, Tenant shall pay
the fixed monthly rental specified in the Escalation Statement until the first
fixed monthly rental payment due at least fifteen (15) days after Tenant
receives the next Escalation Statement, when Tenant shall make the payments
specified in the preceding sentence.

     If the Consumer Price Index is replaced by a successor index published by
the Department of Labor (or successor agency), such successor index shall be
substituted for the Consumer Price Index with such adjustments as may be
published by the Department of Labor (or successor agency) to reconcile such
successor index with the Consumer Price Index.  If the Consumer Price Index (or
such successor index) shall be discontinued with no successor index, the parties
shall attempt to agree upon a substitute index.  If the parties are unable to
agree upon a substitute index, then the matter shall be determined by
arbitration in accordance with the then prevailing rules of the American
Arbitration Association, and judgment upon the award rendered shall be final and
binding upon the parties, and may be entered in any court of competent
jurisdiction.

                                      -9-
<PAGE>

6.  SECURITY DEPOSIT
    ----------------

     Concurrently with Tenant's execution of this Lease, Tenant shall deposit
the sum of Ten Thousand Four Hundred and Forty Five Dollars ($10,445.00), less
amounts already deposited with Landlord under INTEL-L-811 ($6,636.00) which
shall be applied by Landlord towards satisfying Tenant's obligation under this
Article, with Landlord as security for the full and faithful performance by
Tenant of each and every term, provision, covenant, and condition of this Lease.
Landlord shall not be required to keep the security deposit separate from its
other funds and Tenant shall not be entitled to any interest on the security (it
is noted that in lieu of interest, Landlord and Tenant have agreed to an annual
credit of $300 towards Tenant's Operating Expenses payments as indicated in
paragraph 4(b)(1)).  In the event that Tenant is in default of any of the terms,
provisions, covenants, and conditions of this Lease, including but not limited
to payment of any rental, Landlord may use, apply, or retain the whole or any
part of the security so deposited for the payment of any such sum in default, or
for any other sum which Landlord may expend or be required to expend by reason
of Tenant's default, including any damages or deficiencies in the reletting of
the premises, whether such damage or deficiency may occur before or after any
repossession proceeding or other reentry by Landlord.  If the Landlord utilizes
any of the security deposit in curing a default on the part of Tenant, Tenant
shall immediately pay Landlord the amount necessary to restore the security
deposit to its original amount.  The security deposit or any lesser amount
properly remaining under this Lease, shall be returned to Tenant within thirty
(30) days after expiration of the term of this Lease.  The holding, use,
application, or retention of the security deposit by Landlord shall not be
deemed to restrict Landlord's right to possession of the demised premises or to
limit Tenant's liability, under this Lease while the Lease is in full force and
effect.  Upon termination or expiration of this Lease, the holding, use,
application, or retention of the security deposit (or some portion thereof) by
Landlord will reduce Tenant's monetary obligations to Landlord by the amount
held, used, applied, or retained.

7.  PREOCCUPANCY WORK AGREEMENT
    ---------------------------

     Landlord at its sole expense will provide the design services and will
finish the demised premises in accordance with the provisions set forth in
Exhibit B attached hereto and made a part

                                     -10-
<PAGE>

hereof. Landlord shall have no obligation to make any alternations, additions or
improvements to the demised premises except as set forth in Exhibit B; provided,
however, Tenant may, at its own expense, substitute a higher grade item for that
of a building-standard item (e.g., door locks) in which case Tenant shall
receive a credit from INTELSAT for the cost of the building-standard item being
replaced. Immediately following the Lease Commencement Date, Landlord shall work
diligently to complete any remaining construction items identified by Landlord
and Tenant in connection with the required construction. Landlord shall exercise
its best efforts to assure that all such construction items are completed no
later than sixty (60) days following the Lease Commencement Date. Within this
period, Tenant shall inform Landlord in writing of any such construction items,
and Landlord shall work diligently to complete such items within the sixty (60)
day period.

8.  ASSIGNMENT AND SUBLETTING
    -------------------------
    A.  Landlord's Consent Required
        ---------------------------

          Tenant may not assign, transfer, mortgage or encumber this Lease, nor
     sublet the demised premises, or any part thereof, nor shall any assignment
     or transfer of this Lease be effectuated by operation of law or otherwise,
     without first obtaining the prior written consent of Landlord, whose
     consent shall not be unreasonably withheld or delayed.  Any attempted
     assignment, transfer, mortgage, encumbrance or subletting without such
     consent shall be wholly void and shall confer no rights upon any third
     parties.  The consent of Landlord to any assignment, transfer, or
     subletting to any third party shall not be construed as a waiver or release
     of Tenant from the terms of any covenant or obligation under this Lease,
     nor shall the collection or acceptance of rental from any such assignee,
     transferee, subtenant or occupant constitute a waiver or release of Tenant
     of any covenant or obligation contained in this Lease, nor shall any such
     assignment, transfer or subletting be construed to relieve Tenant from
     obtaining the consent in writing of Landlord to any further assignment or
     subletting.  In the event that Tenant defaults hereunder, Tenant hereby
     assigns to Landlord the rental due from any subtenant of Tenant and hereby
     authorizes each such subtenant to pay said rental directly to Landlord.

                                     -11-
<PAGE>

    B.  Tenant's Application (Assignment and Sublease)
        ----------------------------------------------

          In the event that Tenant desires at any time to assign this Lease or
     to sublet the demised premises or any portion thereof, Tenant shall submit
     notice thereof to Landlord at least sixty (60) days prior to the proposed
     effective date of the assignment or sublease ("Proposed Effective Date"),
     in writing, which shall include: (a) a request for permission to assign or
     sublease, setting forth the Proposed Effective Date, which shall be no less
     than sixty (60) nor more than ninety (90) days after the date such notice
     was submitted; (b) the name of the proposed subtenant or assignee; (c) the
     nature of the proposed subtenant's or assignee's business to be carried on
     in the demised premises; (d) the terms, provisions, covenants and
     conditions of the proposed sublease or assignment; and (e) current
     financial information (audited, if available) of Tenant and the proposed
     subtenant or assignee, Tenant shall also promptly submit such additional
     information as Landlord may request in order to make a reasoned judgment.

    C.  Recapture
        ---------

          If Tenant proposes to assign this Lease or to sublet the demised
     premises or any portion thereof, Landlord may, at its option, exercisable
     upon written notice to Tenant within thirty (30) days after receipt of the
     notice from Tenant set forth in paragraph B above, elect to recapture the
     demised premises or portion thereof which Tenant proposes to sublease, and
     terminate this Lease with respect to such recaptured premises.  If Landlord
     does not elect to recapture pursuant to this paragraph C, Tenant may
     thereafter enter into a valid assignment or sublease with respect to the
     demised premises provided Landlord consents thereto, and provided further
     that (a) such assignment or sublease is executed within ninety (90) days
     after notification to Landlord of such proposal, and (b) the rental
     therefrom is not more than that stated in such notification.

    D.  Sharing of Sublet Profits
        -------------------------

          In the event that Tenant sublets the demised premises or any portion
     thereof in accordance with the provisions of this Article, Tenant shall pay
     to Landlord, in addition

                                     -12-
<PAGE>

     to all other payments required by this Lease, 25% of the amount by which
     the proceeds of such sublease exceed Tenant's payments to Landlord for any
     monthly period.

9.  CLEANING AND MAINTENANCE BY TENANT
    ----------------------------------

     Tenant will keep the demised premises and the fixtures and equipment
therein in clean, safe and sanitary condition, will take good care thereof, will
suffer no waste or injury thereto, and will at its sole cost and expense,
promptly make all repairs and perform all maintenance, in and to the demised
premises that are necessary to keep the demised premises in good order and
repair and in a safe and rentable condition, but Tenant shall not be responsible
for maintenance items assumed by Landlord under the terms of this Lease.
Without limiting the generality of the foregoing, Tenant, at its sole cost and
expense, is specifically required to make promptly all repairs (i) to the
demised premises, and (ii) to the interior glass windows, plate glass doors, and
any fixtures or appurtenances composed of glass.  Tenant shall make all repairs
to the demised premises caused by any act or omission of Tenant, or its
employees, agents or invitees.  In the event Tenant fails to maintain the
demised premises in good order, condition and repair, Landlord may (but shall
not be obligated to) give Tenant notice to do such acts as are reasonably
required to so maintain the demised premises.  In the event that after such
notice Tenant shall fail to promptly commence such work and diligently prosecute
it to completion, then Landlord shall have the right to do such acts and expend
such funds at the expense of Tenant as are reasonably required to perform such
work.  Any amount so expended by Landlord shall be paid by Tenant promptly after
demand with interest at the Default Interest Rate defined in Article 28 of this
Lease.  Landlord shall have no liability to Tenant for any damage,
inconvenience, or interference with respect to the use of the demised premises
by Tenant as a result of performing any such work.

10.  ALTERATIONS
     -----------

     Tenant will not make or permit anyone to make any alterations, additions or
improvements, structural or otherwise (hereinafter referred to as
"Alterations"), in or to the demised premises or the Building, without the prior
written consent of Landlord, which consent shall not be unreasonably withheld.
Tenant may wire the demised premises for low-voltage electrical signal purposes
provided the wiring is routed through wall conduits, above panel

                                     -13-
<PAGE>

ceilings, or below panel flooring and provided such wiring is approved in
writing in advance by Landlord. All Alterations made or permitted to be made by
Tenant shall be at Tenant's sole cost and expense. If any mechanic's lien is
filed against the demised premises, the Building, and/or the Land, for work or
materials done for, or furnished to, Tenant (other than for work or materials
supplied by Landlord), such mechanic's lien shall be discharged by Tenant within
ten (10) days thereafter, at Tenant's sole cost and expense, by the payment
thereof or by the filing of any bond required by law. If Tenant shall fail to
discharge any such mechanic's lien, Landlord may, at its option, discharge the
same and treat the cost thereof as additional rental hereunder, payable with the
monthly installment of rental next becoming due; and such discharge by Landlord
shall not be deemed to waive the defaulting of Tenant in not discharging the
same. Tenant will indemnify and hold Landlord harmless from and against any and
all expenses, liens, claims, or damages to person or property which may or might
arise by reason of the making of any Alterations. If any Alteration is made
without the prior written consent of Landlord, Landlord may correct or remove
same, and Tenant shall be liable for all costs and expenses so incurred by
Landlord. All Alterations in or to the demised premises or the Building made by
either party shall immediately become the property of Landlord; provided,
however, nothing in this Article shall be construed to impair Tenant's rights in
its personal property, and its trade fixtures, machinery and equipment which
were installed by Tenant, at its sole cost and expense.

11.  SIGNS AND FURNISHINGS
     ---------------------

     With the exception of notices and signs posted by Tenant within the demised
premises which cannot be seen from the common areas within the Building or from
the grounds outside the Building, no sign, advertisement or notice shall be
inscribed, painted, affixed or displayed by Tenant on any part of the outside or
the inside of the Building except as is approved in advance by Landlord in
writing, which approval shall not be unreasonably withheld, and if any such
sign, advertisement or notice is exhibited, without Landlord's approval,
Landlord shall have the right to remove the same and Tenant shall be liable for
any and all costs and expenses incurred by Landlord by said removal.  Landlord
shall have the right to prescribe the weight and position of safes and other
heavy equipment or fixtures that Tenant desires to install in the demised
premises.  Tenant shall not place a load upon any floor exceeding the floor load
per square foot area which such floor was designed to carry, as specified by
Landlord upon request.  Any and all

                                     -14-
<PAGE>

damage or injury to the demised premises or the Building caused by moving the
property of Tenant into or out of the demised premises, or due to the same being
on the demised premises, shall be repaired by and at the sole cost and expense
of Tenant. No furniture, equipment or other bulky matter of any description will
be received into the Building or carried in the elevators except with prior
consent of Landlord. Tenant shall give Landlord twenty-four (24) hours' prior
notice of the timing of all moving of furniture, machinery, equipment and other
material within the public areas and all such moving shall be conducted in such
manner as Landlord may reasonably require in the interests of all tenants in the
Building. Prior consent of Landlord is not required for Tenant personnel
carrying small hand-held items and equipment under 100 lbs. that can be
conveniently transported through the Building common areas and into the
elevators by a single person using a "luggage-style" handcart with rubber tires;
however, Tenant personnel shall transport such items through the Building common
areas only in a safe and courteous fashion. Tenant may hang pictures, logos, and
other wall furnishings, using small finishing nails, screws or hooks, within the
demised premises provided that substantial damage to the interior walls is not
inflicted. Tenant agrees to remove promptly from the sidewalks adjacent to the
Building any of Tenant's furniture, machinery, equipment or other property.

12.  ENTRY FOR HOUSEKEEPING, REPAIRS AND INSPECTIONS
     -----------------------------------------------

     Tenant will permit Landlord, or its representatives, to enter the demised
premises, at all reasonable times, without diminution of the rental payable by
Tenant, to examine, inspect, protect and maintain the same, to make such
alterations and/or repairs as in the judgment of Landlord may be deemed
necessary to perform housekeeping chores, and, during the last one hundred
eighty (180) days of the term of this Lease, to exhibit the demised premises to
prospective tenants after five business days advance notification to Tenant.

13.  INSURANCE RATING
     ----------------

     Tenant will not conduct or permit to be conducted any activity or place any
machinery, equipment or other property in or about the demised premises, which
will in any way, increase the rate of insurance premiums on the Building; and if
any increase in the rate of insurance premiums is stated by any insurance
company or by the applicable Insurance Rating Bureau to be due to any such
activity or property in or about the demised premises, such statement shall be

                                     -15-
<PAGE>

conclusive evidence that the increase in such rate is due to such activity or
property and, as a result thereof, Tenant shall be liable for such increase, as
additional rental hereunder, and shall reimburse Landlord therefor; provided,
however, that Landlord has provided Tenant with notice of such activity.

14.  TENANT'S EQUIPMENT
     ------------------

     Tenant will not install or operate in the demised premises any electrically
operated equipment, machinery or other property, other than electric
typewriters, calculators, personal computers, desktop or deskside engineering
workstation computers, laser printers, radios, tape recorders and other audio
equipment, televisions and other video equipment, refrigerators, desktop
electronics test, measurement, and prototyping equipment, standard size office
copiers, telex and fax machines, other standard office equipment, and any
special equipment approved in writing by Landlord, provided such equipment or
pieces of equipment does not require special outlet or current exceeding 16 amps
per 20 amp. circuits and such equipment does not exceed the floor loads set
forth in Exhibit B, without first obtaining the prior written consent of
Landlord and a mutually acceptable separate written agreement setting forth the
terms and conditions on which additional electrical power for such items is to
be furnished, including among other things, a provision for payment by Tenant of
additional rental in compensation for such excess consumption of utilities and
for the cost and expense of such additional wiring as may be occasioned by the
operation of said equipment, machinery or other property.  Tenant shall not
install, any other property of any kind or nature whatsoever which may
necessitate any changes, replacements or addition to, or in the use of, the
water, heating, plumbing, air conditioning, or electrical systems of the
Building without first obtaining the prior written consent of Landlord.
Business machines and mechanical equipment or other property belonging to Tenant
which cause noise or vibration that may be transmitted to any part of the
Building to such a degree as to be objectionable to Landlord or to any tenant in
the Building shall be installed and maintained by Tenant, at Tenant's sole cost
and expense, on vibration eliminators or other devices sufficient to eliminate
such noise and vibration.

                                     -16-
<PAGE>

15.  INDEMNITY AND PUBLIC LIABILITY INSURANCE
     ----------------------------------------

     Tenant will indemnify and hold harmless Landlord from and against any loss,
damage, liability, claim, cost or expense (including reasonable attorneys' fees)
incurred by or claimed against Landlord occasioned by or resulting from any
default of Tenant hereunder or any act or omission on the part of Tenant, its
agents, employees, or invitees or arising from or in connection with Tenant's
use or occupancy of the demised premises or which relates to the business of
Tenant, except to the extent due to the negligence or willful misconduct of
Landlord or Landlord's employees or agents.  Notwithstanding the foregoing,
Tenant shall not be liable to Landlord for any loss or damage to personal
property or injury to persons, whether or not the result of any act or omission
of Tenant, to the extent that Landlord is compensated therefor by Landlord's
insurance.  The preceding sentence shall not constitute a waiver of any
subrogation rights of Landlord's insurer.  Tenant shall not be liable for any
interruption or loss to Landlord's business from any cause.  Tenant shall obtain
and maintain in effect at all times during the term of this Lease a policy of
comprehensive public liability insurance, naming Landlord and any mortgagee of
the Building as additional insureds, protecting Landlord, Tenant and any such
mortgagee against any liability for bodily injury, death or property damage
occurring upon, in or about any part of the Building, the grounds, or the
demised premises arising from any of the items set forth in this Article against
which Tenant is required to indemnify Landlord, with such policies to afford
protection (i) with respect to bodily injury or death to the limit of not less
than One Million Dollars ($1,000,000) to any one person and to the limit of not
less than Three Million Dollars ($3,000,000) with respect to any one accident,
and (ii) with respect to damage to the property of any one owner to the limit of
not less than Five Hundred Thousand Dollars ($500,000).  Such insurance policies
shall be issued by responsible insurance companies licensed to do business in
the District of Columbia.  A certificate of insurance evidencing the issuance of
such insurance policy, together with evidence of payment of premiums thereon,
shall be delivered to Landlord upon Landlord's written request prior to the
Lease Commencement Date and at least thirty (30) days before the expiration date
of any policy evidenced by a certificate previously furnished.  Neither the
issuance of any insurance policy required under this Lease, nor the minimum
limits specified herein with respect to Tenant's insurance coverage, shall be
deemed to limit or restrict in any way Tenant's liability arising under or out
of this Lease.

                                     -17-
<PAGE>

Landlord shall maintain in effect at all times property and liability insurance
policies providing a commercially reasonable level of insurance commensurate
with a first-class office building.

16.  SERVICES AND UTILITIES
     ----------------------

    A.  Landlord shall provide, without cost or expense to Tenant, the necessary
    mains, feeders, pipes, ducts and conduits to bring electricity services and
    heating, ventilation and air conditioning (HVAC) services to the demised
    premises. Landlord shall also provide all connections and all outlets,
    risers, wiring, piping, duct work or other means of interior distribution of
    electricity and HVAC service within the demised premises.

    B.  As long as Tenant is not in default under any of the provisions of this
    Lease, Landlord shall provide the following facilities and services to
    Tenant without additional charge to Tenant (except as otherwise provided
    herein):

        (1)   Landlord will provide restroom facilities and necessary lavatory
        supplies, including hot and cold running water, at those points of
        supply provided for general use of other tenants in the Building, and
        routine maintenance, painting and electric lighting service for all
        public areas and special service areas of the Building in the manner and
        to the extent that is standard for similar first-class buildings in
        Washington, D.C.

        (2)   Landlord will provide access to the demised premises on a full-
        time twenty-four hour a day basis, subject to such reasonable
        regulations as Landlord may impose for security purposes.

        (3)   Landlord will provide heating, ventilation and air conditioning
        (HVAC) services as follows:

            (a)   Landlord will provide HVAC services Monday through Friday from
            8:00 A.M. to 6:00 P.M., and Saturday from 9:00 A.M. to 1:00 P.M.
            (holidays recognized by Landlord excepted but not to exceed fourteen
            (14) holidays per year unless otherwise agreed in writing between
            Landlord and Tenant) on an all year round basis.

                                     -18-
<PAGE>

            (b)   Landlord will maintain the building HVAC system, as well as
            the means of interior distribution within the demised premises, and
            will use all reasonable care to maintain the system in proper and
            efficient operating condition. Landlord will not be responsible for
            the failure of the air conditioning system to meet normal
            requirements, if such failure results from the occupancy of the
            demised premises by more than an average of one person for each 100
            square feet, or from faults in any interior distribution system
            provided by Tenant.

            (c)   Tenant agrees to keep and cause to be kept closed, at all
            times, exterior doors in the demised premises, except for normal
            ingress and egress, and Tenant agrees to cooperate fully with
            Landlord and to abide by all the regulations and requirements which
            Landlord may reasonably prescribe for the proper functioning and
            protection of said HVAC system.

            (d)   Landlord will maintain the above building standard air
            conditioning unit identified in Exhibit B for one (1) year and will
            be responsible for all service and repairs of problems reported by
            Tenant within one (1) year of the Lease Commencement Date. Landlord
            will be responsible for design defects for a period of five years.
            In the event of a dispute between Landlord and Tenant as to whether
            a repair is required due to a design defect, such dispute shall be
            finally settled by a third party contractor. Electricity will be
            provided to this air conditioning unit on a full-time twenty-four
            hour a day basis.

        (4)   Landlord will provide hot and cold running water on a full-time
        twenty-four hour a day basis, subject to such reasonable regulations as
        Landlord may impose. Landlord will use all reasonable care to maintain
        the building plumbing system, as well as the interior plumbing within
        the demised premises, in proper and efficient operating condition. In
        the event that a problem with the building plumbing system or the
        interior plumbing within the demised premises is caused

                                     -19-
<PAGE>

        by an act or omission of Tenant, Landlord will correct such problem at
        Tenant's sole cost and expense.

        (5)   Landlord will provide electrical energy which Tenant requires in
        the demised premises for lighting purposes and for operation of
        electrical office equipment, machinery and other property normally
        associated with use of space for office purposes but not including any
        additional requirement of Tenant caused by installation or operation of
        equipment, machinery or property as to which prior written consent of
        Landlord is required under Article 14. Overhead lighting will be
        provided Monday through Friday from 7:00 A.M. to 11:00 P.M., and
        Saturday from 7:00 A.M. to 3:00 P.M. (holidays recognized by Landlord
        excepted but not to exceed fourteen (14) holidays per year unless
        otherwise agreed in writing between Landlord and Tenant).

        (6)   Landlord will provide after hours lighting and HVAC services at
        reasonable hourly rates; provided, that Tenant shall give notice to
        Landlord prior to 1:00 P.M. on the day such service is required in the
        case of after hours service on weekdays, prior to 3:00 P.M. on the
        Friday preceding the day such service is required in the case of after
        hours service on weekends, and prior to 1:00 P.M. on the last business
        day preceding the holiday on which such service is required in the case
        of after hours service on holidays.

        (7)   Landlord will provide after hours Monday through Friday
        maintenance and housekeeping services, including replacement of
        fluorescent bulbs, glass cleaning, dusting, sweeping, vacuuming, and
        removal of trash, in a manner consistent with the standard for similar
        first-class office buildings in Washington, D.C. Such services shall
        also include cleaning the showers, sinks, and kitchen areas within the
        demised premises.

        (8)   Landlord will make available for Tenant's ordinary business usage
        conference rooms and meeting rooms, provided that Tenant shall give
        Landlord forty-eight (48) hours advance notice, and provided that such
        facilities are not scheduled to be used by Landlord or committed for use
        to other eligible users. Tenant's use of

                                     -20-
<PAGE>

        Landlord's conference rooms, adjacent atria, and other areas designed
        for common use by Building occupants for receptions shall require prior
        written permission from Landlord for each individual occasion, which
        permission shall not unreasonably be withheld. Permission shall be
        considered reasonably withheld if such facilities are scheduled for use
        by Landlord or committed for use to other eligible users. Any added
        costs for services such as set-up, restoration, security, engineering
        and catering arising from Tenant's use of Landlord's reception rooms or
        other facilities for any purpose shall be paid by Tenant on a direct
        cost basis plus any general administrative costs to INTELSAT. Catering
        service is available in the Building.

        (9)   Landlord shall maintain the Building common areas in good, safe,
        and sanitary condition and repair.

        (10)   Landlord shall maintain security which is adequate in Landlord's
        reasonable judgment for the Building.

        (11)   Landlord shall provide at least one operational elevator in the
        Building at all times. After notice of an elevator problem, Landlord
        shall undertake to make appropriate repairs with due diligence.

        (12)   Tenant shall be entitled to full access to the cafeteria
        facilities during normal hours of operation.

    C. If Landlord fails to provide any of the services specified in this
    Article, and any such failure continues for fourteen (14) days after
    Landlord receives written notification from Tenant, if such failure renders
    the demised premises unsuitable for normal commercial purposes, then
    Tenant's obligation to pay rent hereunder shall be reduced in proportion to
    the extent the premises are rendered unsuitable for normal commercial
    purposes. If Landlord's failure to provide services affects a substantial
    portion of the demised premises, and renders the demised premises unsuitable
    for normal commercial purposes, and continues for more than thirty (30)
    days, Tenant may, by written notice to

                                     -21-
<PAGE>

    Landlord, terminate this Lease upon a date not less than thirty (30) days
    after the date of such notice.

    D.  Any failure by Landlord to furnish the foregoing services as a result of
    governmental restrictions, energy shortages or from any cause beyond the
    control of Landlord shall not render Landlord liable in any respect for
    damages to either person or property, or loss of Tenant's business, nor be
    construed as an eviction of Tenant, nor work an abatement of rental, nor
    relieve Tenant from Tenant's obligations hereunder. If the Building
    equipment should cease to function properly, Landlord shall use reasonable
    diligence to repair the same. Landlord shall also use reasonable diligence
    to rectify any problem adversely affecting any of the above services and
    utilities.

17.  METERED UTILITIES
     -----------------

     Notwithstanding any contrary provision of this Lease, Tenant agrees to bear
no less than that portion of the cost of the services provided by Landlord as
described in Article 16 above, which clearly reflects the use by Tenant upon or
with respect to the demised premises and the services provided by Landlord with
respect thereto, such as computer utility costs and unusual electricity, air
conditioning, heat or water requirements; and Landlord may, in its sole
discretion, increase or decrease, from time to time during the term of this
Lease, the portion of such costs of such services to be paid by Tenant which
reasonably approximates Tenant's use thereof in excess of the Building Standards
established by Landlord from time to time for normal use of the demised
premises.  Landlord's engineering department may determine or estimate Tenant's
excess use of utility services using industry standards or Landlord may, in its
sole discretion, install separate meters or submeters to measure Tenant's actual
consumption of utility resources in excess of the Building Standards established
by Landlord from time to time for normal use of the demised premises.  The costs
and expenses related to installing such meters or submeters shall be borne by
Landlord.  In the event of excess consumption of utility services, Landlord
shall bill Tenant periodically for utility usage upon or with respect to the
demised premises, in excess of the Building Standards established by Landlord
from time to time for normal use, together with a reasonable administration
charge.  The amount specified in such bill shall

                                     -22-
<PAGE>

become additional rental due and payable with the installment of fixed monthly
rental next becoming due under the terms of this Lease.

18.  RESPONSIBILITY FOR DAMAGE TO DEMISED PREMISES
     ---------------------------------------------

     All injury or damage to the demised premises or the Building caused by
Tenant or any of its agents, employees and invitees, shall be repaired promptly
by Tenant at Tenant's sole cost and expense.  If Tenant shall fail to so repair,
Landlord shall have the right to make such repairs or replacements and any cost
or expense so incurred by Landlord shall be paid by Tenant, in which event such
cost and expense shall become additional rental due and payable with the
installment of fixed monthly rental next becoming due under the terms of this
Lease.  All injury or damage to the demised premises or the Building caused by
the act or omission of Landlord, or any of its agents, employees and invitees,
shall be the responsibility of Landlord and shall be repaired with due diligence
and as soon as practicable, at Landlord's sole cost and expense, and in no event
shall Tenant be liable for any such injury or damage caused by the act or
omission of Landlord or any of its agents, employees and invitees.

19.  LIABILITY FOR DAMAGE TO PERSONAL PROPERTY AND PERSONS
     -----------------------------------------------------

     All personal property of Tenant and its employees, agents and invitees in
or about the demised premises shall be and remain at their sole risk.  Landlord
shall not be liable for any damage to or loss of such personal property arising
from any act or omission of any person, or from any cause other than any damage
or loss except to the extent that it results directly from the negligence or
willful misconduct of Landlord.  Landlord shall not be liable for any personal
injury, including death, to Tenant, its employees, agents, or invitees, arising
from the use, occupancy or condition of the demised premises except to the
extent it arises from the negligence or willful misconduct of Landlord.
Notwithstanding the foregoing, Landlord shall not be liable to Tenant for any
loss or damage to personal property or injury, including death, to persons,
whether or not the result of Landlord's negligence or willful misconduct, to the
extent that Tenant is compensated therefor by Tenant's insurance.  The preceding
sentence shall not constitute a waiver of subrogation rights of Tenant's
insurer.  Landlord shall not be liable for any interruption or loss to Tenant's
business from any cause.

                                     -23-
<PAGE>

20.  FIRE AND OTHER CASUALTY DAMAGE TO DEMISED PREMISES
     --------------------------------------------------
     A.  Damage Generally
         ----------------

          If the demised premises shall be damaged by fire or other cause, other
     than a cause resulting from the act or omission of Tenant or its agent,
     employee or invitee, Landlord shall as soon as practicable after such
     damage occurs (taking into account the time necessary to effectuate a
     satisfactory settlement with any insurance company) repair the demised
     premises to the condition originally furnished by Landlord, at the sole
     cost and expense of Landlord, on the Lease Commencement Date, and the
     rental shall be reduced in proportion to the extent the demised premises
     are rendered untenantable, as reasonably agreed to by Landlord and Tenant,
     until such repairs are completed.  Landlord shall not be obligated to
     restore any alterations, additions or improvements to the demised premises
     installed by Tenant, including but not limited to those installed pursuant
     to Articles 7 and 10, it being expressly agreed and understood that Tenant
     shall carry insurance to cover such alterations, additions and improvements
     and Landlord shall not be required to insure such alterations, additions
     and improvements under such insurance as Landlord may carry upon the
     demised premises.  No compensation or reduction of rent will be paid or
     allowed by Landlord by reason of inconvenience, annoyance, or injury to
     business arising from the necessity of repairing the demised premises or
     any portion of the Building or the grounds.

     B.  Exceptions to Obligation to Rebuild
         -----------------------------------

          Notwithstanding the provisions of paragraph A of this Article, if
     substantial alteration or reconstruction of the Building shall, in the
     opinion of Landlord, be required as a result of damage by fire or other
     cause (whether or not the demised premises shall have been damaged by such
     fire or other cause and whether or not such damage is covered by insurance
     carried by Landlord), or if the proceeds of available insurance are less
     than one hundred percent (100%) of the cost of restoration, or if the
     damage to the demised premises or the Building is a result of an uninsured
     risk, then this Lease and the term and estate hereby granted may be
     terminated by Landlord by its giving to Tenant, within one hundred twenty
     (120) days after the date of such damage, a notice specifying a

                                     -24-
<PAGE>

     date, not less than sixty (60) days after giving of such notice, for such
     termination. In the event of the giving of such notice of termination, this
     Lease and the term and estate hereby granted shall cease and terminate as
     of the date specified therefor in such notice, and the fixed monthly rental
     and all other rental payable hereunder shall be prorated as of the date of
     termination. Additionally, it is agreed that if the demised premises or the
     Building is so substantially destroyed that reconstruction cannot be
     substantially completed within one hundred twenty (120) days from the date
     of destruction, Tenant may elect to terminate this Lease by giving Landlord
     written notice of such election within sixty (60) days after the date of
     such damage. Such termination shall be effective as of the date specified
     in such notice, which date shall not be less than sixty (60) days after
     said notice. Notwithstanding the foregoing, in the event that the demised
     premises are not damaged but the Building is substantially destroyed,
     Tenant shall have the above termination rights only in the event that said
     destruction of the Building (considering all relevant factors) results in
     the demised premises being unsuitable for normal commercial purposes.

21.  BANKRUPTCY OR INSOLVENCY
     ------------------------

     A.  Events of Bankruptcy
     --------------------
          The following shall be Events of Bankruptcy under this Lease:

          (1)   Tenant's becoming insolvent, as that term is defined in Title 11
          of the United States Code, entitled Bankruptcy, 11 U.S.C., Para. 101
          et seq. (The "Bankruptcy Code"), or under the applicable insolvency
          laws of any State, District, Commonwealth or Territory of the United
          States ("Insolvency Laws");

          (2)   The appointment of a receiver or custodian for any or all of
          Tenant's property or assets, or the institution of a foreclosure
          action upon any of Tenant's real or personal property;

          (3)   The filing of a voluntary petition under the provisions of the
          Bankruptcy Code or Insolvency Laws;

                                     -25-
<PAGE>

          (4)   The filing of an involuntary petition against Tenant as the
          subject debtor under the Bankruptcy Code or Insolvency Laws, which is
          either not dismissed within sixty (60) days of filing, or results in
          the issuance of an order for relief against the debtor, whichever is
          later; or

          (5)   Tenant's making or consenting to an assignment for the benefit
          of creditors or a common law composition of creditors.

     B.  Landlord's Remedies
     -------------------

          (1)    Termination of Lease
                 --------------------

               Upon the occurrence of an Event of Bankruptcy, Landlord shall
          have the right to terminate this Lease by giving written notice to
          Tenant; provided, however, that this subparagraph B.(1) shall have no
          effect while a case in which Tenant is the subject debtor under the
          Bankruptcy Code is pending, unless Tenant or its Trustee in bankruptcy
          is unable to comply with the provisions of subparagraphs B.(4) and
          B.(5) hereof; otherwise this Lease shall automatically cease and
          terminate, and Tenant shall be immediately obligated to quit the
          premises upon the giving of notice pursuant to this subparagraph
          B.(1).  Any other notice to quit or notice of Landlord's intention to
          reenter is hereby expressly waived.  If Landlord elects to terminate
          this Lease, everything contained in this Lease on the part of Landlord
          to be done and performed shall cease without prejudice; however, such
          termination shall not effect the right of Landlord to recover from
          Tenant all rental and any other sums accrued up to the time of
          termination or recovery of possession by Landlord, whichever is later,
          and any other monetary damages or loss of reserved rental sustained by
          Landlord.

                                     -26-
<PAGE>

          (2)    Suit for Possession
                 -------------------

               Upon termination of this Lease pursuant to subparagraph B.(1)
          hereof, Landlord may proceed to recover possession of the demised
          premises under and by virtue of the provisions of the laws of the
          District of Columbia, or by such other proceedings, including reentry
          and possession, as may be applicable.

          (3)    Reletting of Demised Premises
                 -----------------------------

               Upon termination of this Lease pursuant to subparagraph B.(1)
          hereof, the demised premises may be relet by Landlord for such rental
          and upon such terms as are not unreasonable under the circumstances
          and, if the full rental reserved under this Lease (and any of the
          cost, expenses or damages incurred by Landlord) shall not be realized
          by Landlord, Tenant shall be liable for all such costs, expenses and
          damages sustained by Landlord in accordance with the provisions of
          Article 22 hereof.

          (4)   Assumption or Assignment by Trustee
                -----------------------------------

               In the event Tenant becomes the subject debtor in a case pending
          under the Bankruptcy Code, Landlord's right to terminate this Lease
          pursuant to this Article 21 shall be subject to the rights of the
          Trustee in bankruptcy to assume or assign this Lease.  The Trustee
          shall not have the right to assume or assign this Lease unless the
          Trustee (a) promptly cures all defaults under this Lease, (b) promptly
          compensates Landlord for monetary damages incurred as a result of such
          default, and (c) provides adequate assurance of future performance.

          (5)   Adequate Assurance of Future Performance
                ----------------------------------------

               Landlord and Tenant hereby agree in advance that adequate
          assurance of future performance, as used in subparagraph B.(4) hereof
          shall mean that all of the following minimum criteria must be met: (a)
          the Trustee must pay to Landlord at the time the next installment of
          monthly rental is then due and payable under this Lease, in addition
          to payment of such fixed monthly rental, an amount equal

                                     -27-
<PAGE>

          to the next three (3) months monthly rental due under this Lease, said
          amount to be held by Landlord as an additional security deposit in
          accordance with the provisions of Article 6 and this Article 21, until
          either the Trustee or Tenant defaults in its payments of rental or
          other obligations under this Lease (whereupon Landlord shall have the
          right to draw on such funds) or until the expiration of this Lease
          (whereupon the funds shall be returned to the Trustee or Tenant); (b)
          the Tenant or Trustee must agree to pay to Landlord, at any time the
          Landlord is authorized and does draw on the funds, the amount
          necessary to restore such funds to the original level required by said
          provision; and (c) the Trustee must agree that the use of the premises
          as stated in this Lease will remain unchanged.

          (6)   Failure to Provide Adequate Assurance
                -------------------------------------

               In the event Tenant is unable to (a) cure its defaults, (b)
          reimburse Landlord for its monetary damages, (c) pay the rental due
          under this Lease, or any other payments required of Tenant under this
          Lease, on time (or within ten (10) days of the due date), and (d) meet
          the criteria and obligations imposed by subparagraph B.(5) hereof,
          then Tenant agrees in advance that it has not met its burden to
          provide adequate assurance of future performance, and this Lease may
          be terminated by Landlord in accordance with paragraph B hereof.

22.  DEFAULT OF TENANT
     -----------------
     A.  Breach of Obligations
         ---------------------

          If Tenant shall (a) fail to pay any installment of rental as aforesaid
     or fail to timely make any other payment required by the terms and
     provisions hereof and such failure to pay shall continue for more than ten
     (10) days after written notice thereof to Tenant by Landlord; or (b)
     violate or fail to perform any of the other terms, conditions, provisions,
     covenants or agreements herein made by Tenant, and if such violation or
     failure shall continue for a period of ten (10) days after written notice
     thereof to Tenant by Landlord, or if in a case involving a failure to
     perform an obligation not involving the payment of money where such failure
     to perform cannot be corrected with reasonable diligence

                                     -28-
<PAGE>

     within ten (10) days, Tenant does not begin to correct the failure to
     perform within ten (10) days after written notice thereof to Tenant by
     Landlord and/or Tenant thereafter does not use reasonable diligence to
     correct the failure to perform; or (c) if Tenant shall abandon or vacate
     the demised premises before the Lease Expiration Date, then and in any of
     said events Landlord shall have the right, at its election, then or at any
     time thereafter while such event of default shall continue to give Tenant
     written notice of its intent to terminate this Lease on the date of such
     notice or on any later date specified therein, and on the date specified in
     such notice Tenant's right to possession of the demised premises shall
     cease and this Lease shall thereupon be terminated.

     B.  Liability of Tenant
         -------------------

          If Landlord terminates this Lease pursuant to this Article 22, Tenant
     shall remain liable (in addition to accrued liabilities) for (i) the rental
     and all other sums provided for in this Lease which would have been due and
     payable to Landlord had such termination not occurred, or any and all costs
     and expenses incurred by Landlord in reentering the demised premises,
     repossessing the same, making good any default of Tenant, painting,
     altering or dividing the demised premises, putting the same in proper
     repair, protecting and preserving the same by placing therein watchmen and
     caretakers, reletting the same (including any and all attorney's fees and
     disbursements and brokerage fees incurred in so doing), and any and all
     costs and expenses which Landlord may incur during the occupancy of any new
     tenant or subtenant; less (ii) the net proceeds of any reletting prior to
     the date when this Lease would have expired if it had not been terminated.
     Tenant agrees to pay to Landlord the difference between items (i) and (ii)
     to the foregoing sentence with respect to each month during the term of
     this Lease, at the end of such month.  Any suit, action or proceeding
     brought by Landlord to enforce collection of such difference for any one
     month shall not prejudice Landlord's right to enforce the collection of any
     difference for any subsequent month.  In addition to the foregoing, and
     without regard to whether this Lease is terminated, Tenant shall pay to
     Landlord all costs and expenses incurred, including reasonable attorney's
     fees, with respect to any successful lawsuit or action instituted by
     Landlord to enforce the provisions of this Lease.  Landlord shall have the
     right, at its sole option, to relet the whole or any part of the demised

                                     -29-
<PAGE>

     premises for the whole of the unexpired term of this Lease, or longer, or
     from time to time for shorter periods, for any rental then obtainable,
     giving such concessions of rental and making such special repairs,
     alterations, improvements, additions, decorations and paintings for any new
     tenant as Landlord, in its sole and absolute discretion, may deem
     advisable.  Tenant's liability as aforesaid shall survive the institution
     of summary proceedings and the issuance of any warrant thereunder.
     Landlord shall be under no obligation to relet the demised premises, but
     agrees to use reasonable efforts to do so.  If Landlord terminates this
     Lease pursuant to this Article 22, Landlord shall have the right, at any
     time, at its option, to require Tenant to pay to Landlord, on demand, as
     liquidated and agreed final damages in lieu of Tenant's liability for
     damages hereunder, the rental and all other charges which would have been
     payable from the date of such demand to the date when this Lease would have
     expired if it had not been terminated, minus the fair rental value of the
     demised premises for the same period.  If the demised premises shall have
     been relet for all or part of the remaining balance of the term by Landlord
     after a default but before presentation of proof of such liquidated
     damages, the amount of rental reserved upon such reletting, absent proof to
     the contrary, shall be deemed the fair rental value of the demised premises
     for purposes of the foregoing determination of liquidated damages.  Upon
     payment of such liquidated and agreed final damages, Tenant shall be
     released from all further liability under this Lease with respect to the
     period after the date of such demand.  For purposes of this Article 22, the
     term rental shall include fixed monthly rental, additional rental and all
     other charges to be paid by Tenant under this Lease.  All rights and
     remedies of Landlord under this Lease shall be cumulative and shall not be
     exclusive of any other rights and remedies provided to Landlord under
     applicable law.

     C.  Attorneys' Fees
         ---------------

          If as a result of any breach or default by Tenant in the performance
     of any of the provisions of this Lease, Landlord uses the services of an
     attorney in order to secure compliance with such provisions, recover
     damages therefor, terminate this Lease or evict Tenant, Tenant shall
     reimburse Landlord upon demand for all reasonable attorneys' fees and
     expenses so incurred by Landlord, but only if Landlord prevails in such
     pursuits.

                                     -30-
<PAGE>

          If as a result of any breach or default by Landlord in the performance
     of any of the provisions of this Lease, Tenant uses the services of an
     attorney in order to secure compliance with such provisions, recover
     damages therefor, or terminate this Lease, Landlord shall reimburse Tenant
     upon demand for all reasonable attorneys' fees and expenses so incurred by
     Tenant, but only if Tenant prevails in such pursuits.

23.  WAIVER
     ------

     If under the provisions hereof Landlord shall institute proceedings and a
compromise or settlement thereof shall be made, the same shall not constitute a
waiver of any covenant herein contained nor of any Landlord's rights hereunder.
No waiver by Landlord of any breach of any term, covenant, provision, condition
or agreement herein contained shall operate as a waiver of such term, covenant,
provision, condition, or agreement itself, or of any subsequent breach thereof.
No payment by Tenant or receipt by Landlord of a lesser amount than the
stipulated installments of fixed monthly rental or additional rental shall be
deemed to be other than on account of the earliest stipulated fixed monthly
rental or additional rental, respectively, nor shall any endorsement or
statement on any check or letter accompanying a check for payment of rental or
any other amounts owed to Landlord be deemed an accord and satisfaction and
Landlord may accept such check or payment without prejudice to Landlord's right
to recover the balance of such rental or other amount owed or to pursue any
other remedy provided in this Lease.  No reentry by Landlord, and no acceptance
by Landlord of keys from Tenant, shall be considered an acceptance of a
surrender of this Lease.

24.  FIRST MORTGAGE
     --------------

     This Lease is subject and subordinate to the lien of any first mortgage
(which term "mortgage" shall include both construction and permanent financing
and shall include deeds of trust and similar security instruments) which may now
or hereafter encumber or otherwise affect the Land and the Building or
Landlord's interest therein, and to all and any renewals, extensions,
modifications, recastings or refinancings thereof, but shall not be subordinate
to any mortgage other than a first mortgage.  In confirmation of such
subordination, Tenant shall, at Landlord's request, promptly execute any
requisite or appropriate certificate or other document.  Tenant agrees that in
the event that any proceedings are brought for the foreclosure of any such

                                     -31-
<PAGE>

mortgage, Tenant shall attorn to the purchaser at such foreclosure sale, if
requested to do so by such purchaser, and shall recognize such purchaser as the
Landlord under this Lease, and Tenant waives the provisions of any statute or
rule of law, now or hereafter in effect, which may give or purport to give
Tenant any right to terminate or otherwise adversely affect this Lease and the
obligations of Tenant hereunder in the event that any such foreclosure
proceeding is prosecuted or completed.

25.  ATTORNMENT
     ----------

     In the event of (a) a transfer of Landlord's interest in the Land or
Building, (b) the termination of any ground or underlying lease of the Land or
Building, or (c) the purchase of the Building or Landlord's interest therein at
a foreclosure sale or by deed in lieu of foreclosure under any first mortgage or
pursuant to a power of sale contained in any first mortgage, then in any of such
events Tenant shall attorn to and recognize the transferee or purchaser of
Landlord's interest or the lessor under the terminated ground or underlying
lease, as the case may be, as Landlord under this Lease for the balance of the
then remainder of the term, and thereafter this Lease shall continue as a direct
lease between such person, as Landlord, and Tenant, and such lessor, transferee
or purchaser shall not be liable for any act or omission of Landlord prior to
such person's succession to title, nor be subject to any offset, defense or
counterclaim, accruing prior to such lease termination or prior to such person's
succession to title, nor be bound by any payment of fixed monthly rental or
additional rental prior to such lease termination or prior to such person's
succession to title for more than two (2) months in advance.  Tenant agrees
that, within five (5) days after written request therefor, it will, from time to
time, execute and deliver any instrument or other document required by any
mortgagee, transferee, purchaser or other interested person to confirm such
attornment and/or such obligation to attorn.

26.  CONDEMNATION
     ------------

     If the whole or a substantial part of the demised premises shall be taken
or condemned by any governmental authority for any public or quasi-public use or
purpose, then the term of this Lease shall cease and terminate as of the date
when title vests in such governmental authority, and the rental shall be abated
on such date.  In the event that Tenant accepts replacement office space offered
by Landlord, the rental shall be equitably adjusted for the period of time, if
any,

                                     -32-
<PAGE>

between the date that title vests in such governmental authority and the date
that such replacement office space is available for occupancy by Tenant. If less
than a substantial part of the demised premises is taken or condemned by any
governmental authority for any public or quasi-public use or purpose, the rental
shall be equitably adjusted on the date when title vests in such governmental
authority and this Lease shall otherwise continue in full force and effect. For
purposes hereof, a substantial part of the demised premises shall be considered
to have been taken if more than fifteen percent (15%) of the demised premises
are unusable by Tenant. In the case of any such taking or condemnation, whether
or not involving the whole or a substantial part of the demised premises, Tenant
shall have no claim against Landlord for any portion of the amount that may be
awarded as damages as a result of such taking or condemnation or for the value
of any unexpired term of this Lease.

27.  RULES AND REGULATIONS
     ---------------------

     Tenant, its agents, employees and invitees shall abide by and observe the
rules and regulations attached hereto as Exhibit C.  Tenant, its agents,
employees and invitees, shall abide by and observe such other rules or
regulations as may be promulgated from time to time by Landlord for the
operation and maintenance of the Building provided that the same are not
inconsistent with the provisions of this Lease and a copy thereof is sent to
Tenant.  Landlord shall be obligated to enforce, in a commercially reasonable
manner, the Building's rules and regulations as against all tenants in the
Building.  In particular, Landlord will take commercially reasonable steps to
protect Tenant's quiet enjoyment of its premises.

28.  RIGHT OF LANDLORD TO CURE TENANT'S DEFAULT; LATE PAYMENTS
     ---------------------------------------------------------

     If Tenant defaults in the making of any payment or in the doing of any act
herein required to be made or done by Tenant, then after twenty (20) days notice
from Landlord, Landlord may, but shall not be required to, make such payment or
do such act, and the amount of the cost and expense thereof, if made or done by
Landlord, with interest thereon at the Default Interest Rate (hereafter defined)
from the date paid by Landlord, shall be paid by Tenant to Landlord and shall
constitute additional rental hereunder due and payable with the next installment
of fixed monthly rental; but the making of such payment or the doing of such act
by Landlord shall not operate to cure such default or to estop Landlord from the
pursuit of any remedy to which Landlord would

                                     -33-
<PAGE>

otherwise be entitled. If Tenant fails to pay any installment of rental on or
within five (5) days after the day when such installment is due and payable,
such unpaid installment shall bear interest at the rate of the Default Interest
Rate from the date which is five (5) days after the date when such installment
became due and payable to the date of payment thereof by Tenant. In addition,
Tenant shall pay to Landlord, as a "late charge," four percent (4%) of any
payment herein required to be made by Tenant which is more than ten (10) days
late to cover the costs of collecting amounts past due. Such interest and late
charge shall constitute additional rental hereunder due and payable with the
next installment of fixed monthly rental. For purposes hereof, the Default
Interest Rate shall be the prime interest rate charged by Riggs National Bank
during the period of such default plus two percent (2%) per annum.

29.  NO PARTNERSHIP
     --------------

     Nothing contained in this Lease shall be deemed or construed to create a
partnership or joint venture of or between Landlord and Tenant or to create any
other relationship between the parties hereto other than that of Landlord and
Tenant.

30.  NO REPRESENTATIONS BY LANDLORD
     ------------------------------

     Neither Landlord nor any agent, employee or representative of Landlord has
made any representations or promises with respect to the demised premises or the
Building except as herein expressly set forth, and no rights, privileges,
easements or licenses are granted to Tenant except as herein set forth.
Furthermore, Tenant understands and agrees that Landlord has made no commitment
and is under no obligation to utilize Tenant's services, to purchase any goods
from Tenant or to enter into any relationship with Tenant other than that of
Landlord and Tenant as established pursuant to the provisions of this Lease.
Tenant also acknowledges and agrees that it has not entered into this Lease in
reliance upon, nor are its obligations hereunder conditioned upon Landlord
utilizing any of its services, purchasing any goods from it, or entering into
any relationship with Tenant other than that of Landlord and Tenant.

31.  BROKERS
     -------

     Tenant shall indemnify and hold Landlord harmless from all damages
(including reasonable attorneys' fees and costs) resulting from any claims that
may be asserted against

                                     -34-
<PAGE>

Landlord by any broker, finder or other person with whom Tenant has dealt.
Tenant understands and agrees that any representation or statement by any third
party engaged by Landlord as an independent contractor which is made with regard
to the demised premises or the Building shall not be binding upon Landlord nor
serve as a modification of this Lease and Landlord shall have no liability
therefor, except to the extent such representation is also contained herein or
is approved in writing by Landlord.

32.  NOTICES
     -------

     All notices or other communications hereunder shall be in writing and shall
be deemed duly given if delivered in person or sent by certified or registered
mail, return receipt requested, first class, postage prepaid,

                  (i)  if to Landlord, at:

                       INTELSAT
                       3400 International Drive, N.W.
                       Washington, D.C.  20008-3098

                       Attn:  Department Manager, Facilities Management and
                              Office Services

                  (ii) if to Tenant, at:

                       MIL 3, Inc.
                       Pod 4L
                       3400 International Drive, N.W.
                       Washington, D.C.  20008-3098

                       Attn:  Mr. Alain Cohen

prior to the Lease Commencement Date and, with respect to Tenant, at the demised
premises after the Lease Commencement Date, unless notice of a change of address
is given pursuant to the provisions of this Article.

33.  ESTOPPEL CERTIFICATES
     ---------------------

     Tenant agrees, at any time and from time to time, upon not less than ten
(10) days prior written notice by Landlord, to execute, acknowledge and deliver
to Landlord a statement in

                                     -35-
<PAGE>

writing (i) certifying that this Lease has been unmodified since its execution
and is in full force and effect (or if there have been modifications, that this
Lease is in full force and effect, as modified, and stating the modifications),
(ii) stating the dates, if any, to which the fixed monthly rental and additional
rental hereunder have been paid by Tenant, (iii) stating whether or not to the
knowledge of Tenant, there are then existing any defaults under this Lease (and,
if so, specifying the same), and (iv) stating the address to which notices to
Tenant should be sent. Any such statement delivered pursuant hereto may be
relied upon by Landlord or any prospective purchaser or mortgagee of the Land
and/or Building or any part thereof or estate therein.

34.  COVENANTS OF LANDLORD
     ---------------------

     Landlord covenants that it has the right to make this Lease, and that if
Tenant shall pay the rental and perform all of Tenant's obligations under this
Lease, Tenant shall, during the term hereof, freely, peaceably and quietly
occupy and enjoy the full possession of the demised premises without molestation
or hindrance by Landlord or any party claiming through or under Landlord.  In
the event of any sale or transfer of Landlord's interest in the demised
premises, the covenants and obligations of Landlord under this Lease accruing
after the date of such sale or transfer shall be imposed upon such successor-in-
interest (subject to the provisions of Articles 24 and 25 hereof) and any prior
Landlord shall be freed and relieved of all covenants and obligations of
Landlord hereunder accruing after the date of such sale or transfer.

35.  SURRENDER OF DEMISED PREMISES
     -----------------------------

     Upon the expiration or termination of the term of this Lease, Tenant shall
quit and surrender to Landlord the demised premises, including all improvements,
additions or alterations made or permitted pursuant to Articles 7 and 10, broom
clean, in good order and condition, ordinary wear and tear and acts of God
excepted, and Landlord shall have the right to reenter and resume possession of
the demised premises.  Tenant shall, prior to expiration or termination of this
Lease, and at its sole cost and expense, remove all of its personal property,
trade fixtures, machinery and equipment installed in the demised premises and
restore the demised premises to the condition existing at the commencement of
the lease allowing for reasonable wear and tear, or as otherwise agreed by
Landlord and Tenant, and if such property is not removed by Tenant prior to
expiration or termination of this Lease, it shall, at Landlord's option, become
the

                                     -36-
<PAGE>

property of Landlord and shall be surrendered with the demised premises as a
part thereof. Should Tenant fail (i) to remove any of its personal property,
trade fixtures, machinery and/or equipment, as required hereunder, or (ii) to
restore the demised premises as aforesaid, Landlord may remove same and restore
the demised premises at Tenant's sole cost and expense and Tenant shall
reimburse Landlord for all cost, expense, damages and losses which Landlord
sustains by reason of such failure by Tenant to remove and/or restore. When
Tenant surrenders the premises, Tenant may remove the upgraded locks installed
by Tenant at no cost to Tenant.

36.  HOLDING OVER
     ------------

     If Tenant shall hold possession of the demised premises after the end of
the term of this Lease, Tenant shall be deemed to be occupying the demised
premises as a Tenant from month to month, at one and one half times the monthly
rental then in effect if such holdover occurs without the Landlord's written
consent and at the monthly rental then in effect if such holdover occurs with
the Landlord's written consent, and subject to all the other terms, conditions,
provisions, covenants and obligations of this Lease insofar as the same are
applicable, or as same shall be adjusted, to a month-to-month tenancy.

37.  LIEN FOR RENT
     -------------

     If Tenant does not cure a default under this Lease within ten (10) days
after receiving notice of such default from Landlord, or if Tenant vacates the
premises without Landlord's approval, then in either event, Landlord shall have
a lien on all property of Tenant contained within the demised premises at the
time of the default and such property shall be and remain subject to such lien
of Landlord for payment of all rental and all other sums agreed to be paid by
Tenant herein or for services or costs and expenses relating to the demised
premises that Tenant may hereafter become liable to pay to Landlord.

38.  UNDERLYING LEASE
     ----------------

     Tenant acknowledges that it has been advised of the Lease Agreement between
the Government of the United States as Lessor and Landlord as Lessee dated 8
June 1982, as amended on 22 February 1985, which is sometimes herein referred to
as the Underlying Lease.

                                     -37-
<PAGE>

Tenant agrees that it will not do or cause to be done anything which would
constitute a breach of obligations of Landlord as Lessee under said Underlying
Lease.

39.  SALES AND EXCISE TAXES
     ----------------------

     If during the term of this Lease any governmental authority shall impose a
sales, use, excise or any other tax, with the exception of taxes based upon
Landlord's gross income, on the rentals payable by Tenant hereunder, Tenant
shall pay such tax (or reimburse Landlord for any such tax paid by Landlord)
within ten (10) days after request therefor by Landlord to Tenant.

40.  REPORTING OF PAYMENTS
     ---------------------

     A.  The Tenant agrees to provide to INTELSAT any and all information
     concerning any form of inducement or payment, with a value exceeding U.S.
     $100 ("gratuity") which is given, directly or indirectly, at any time, by
     or on behalf of the Tenant to any INTELSAT Official in connection with this
     Lease. If the value of this Lease exceeds U.S. $500,000, the Tenant shall
     also cause its firm of independent certified public accountants to certify
     to the internal auditor of INTELSAT annually that all such information
     known to such firm has been so provided.

     B.  If INTELSAT determines that any such gratuity has been given for the
     purpose of obtaining this Lease or favorable treatment under this Lease,
     INTELSAT shall be entitled to treat the giving of such gratuity as a
     material breach of this Lease, to terminate this Lease by giving written
     notice of termination to Tenant, and to receive from Tenant punitive
     damages in addition to any other damages .

     C.  The rights and remedies of INTELSAT under this Article are in addition
     to any other rights and remedies provided by law or under this Lease.

     D.  For the purposes of this Article, "INTELSAT Official" includes any
     officer, agent, servant or employee of INTELSAT, its Signatories, or its
     Parties, and any person accredited to attend meetings of INTELSAT organs.

                                     -38-
<PAGE>

41.  GENDER
     ------

     Feminine or neuter pronouns shall be substituted for those of the masculine
form, and the plural shall be substituted for the singular, in any place or
places herein in which the context may require such substitution.

42.  BENEFIT AND BURDEN
     ------------------

     The provisions of this Lease shall be binding upon and inure to the benefit
of the parties hereto and each of their permitted successors and assigns.
Landlord may freely and fully assign its interest or delegate its obligations
hereunder.

43.  GOVERNING LAW
     -------------

     It is the intention of the parties hereto that this Lease (and the terms,
conditions, provisions and covenants hereof) shall be construed and enforced in
accordance with the laws of the District of Columbia.  Landlord and Tenant each
hereby waive any objection to the venue of any action filed by either party in
any court situated in the District of Columbia and each party further waives any
right, claim or power, under the doctrine of forum non conveniens or otherwise,
to transfer any such action filed by any party to any other court.

44.  WAIVER OF TRIAL BY JURY
     -----------------------

     Each party hereby waives all right to trial by jury in any claim, action,
proceeding or counterclaim by either party against the other on any matters
arising out of or in any way connected with this Lease, the relationship of the
parties, Tenant's use or occupancy of the demised premises and/or any claim of
injury or damage.

45.  OPTION TO LEASE ADDITIONAL OFFICE SPACE
     ---------------------------------------

     In the event space in addition to the demised premises becomes available
for commercial use at any time during the Term (including any extensions
thereof) in Pods 2L, 4L or 7L, and Landlord does not require such additional
space for its own use, Landlord shall provide written notice to Tenant of the
availability of such additional space and Tenant shall have an option,
exercisable by providing written notice to Landlord no later than ten (10) days
from the date of

                                     -39-
<PAGE>

receipt of Landlord's notice, to lease from Landlord, in addition to the demised
premises, the additional space referenced in Landlord's notice; provided,
however, that based upon Landlord's own need for office space Landlord may make
its offering of space in Pod 7L conditional upon Tenant vacating office space
within its leased premises located in Pods 4L and 2L.

46.  PARKING OPTION
     --------------

     During the term of this Lease, Tenant shall have the right to rent from
Landlord, on a monthly basis, up to six (6) underground parking space at rates
now or hereinafter established by Landlord (currently $75.00), which rates shall
not be in excess of the monthly parking rates generally charged other Tenants in
the Building for similar parking spaces.  The parking fee may be modified from
time to time at the sole discretion of Landlord, provided that the parking fee
may not exceed the market rental for similar commercial parking space in the
area.

47.  MISCELLANEOUS
     -------------

     Window Blinds - Landlord, at its sole expense, shall promptly install
     -------------
window blinds on the exterior windows of Pod 4L pending a decision by the
appropriate governmental authority.  If such blinds are damaged prior to
Tenant's occupancy of the 4L space, Landlord shall repair the damage or replace
the blinds.  Such window blinds shall not be removed or replaced by Landlord
unless and until such blinds are expressly prohibited by appropriate
governmental authority.  Tenant may, at its sole option and expense, install
such blinds or screens in Pod 2L as soon as the appropriate governmental
approvals have been obtained.

     Cable Television - Landlord shall cooperate with Tenant's efforts to obtain
     ----------------
cable television in its offices; however, all cabling costs associated with such
efforts and services shall be borne by Tenant.

     Smoking - Throughout the term of the Lease Agreement, INTELSAT shall
     -------
enforce in a commercially reasonable fashion the smoking policy set forth in the
INTELSAT Rules and Regulations (Exhibit C).

     Quiet Enjoyment - Tenant's quiet enjoyment of the demised premises shall be
     ---------------
protected by Landlord in a commercially reasonable fashion.

                                     -40-
<PAGE>

     Final Lease Agreement - This Lease Agreement shall supersede in full the
     ---------------------
existing Lease Agreement between the parties, INTEL-L-811, as of the Lease
Commencement Date provided herein.

48.  ENTIRE AGREEMENT
     ----------------

     This Lease, including all exhibits, schedules and addenda attached hereto,
constitutes the entire agreement of the parties hereto, and supersedes all prior
representations, inducements, or agreements, oral or otherwise, between the
parties with respect to the subject matter hereof.  No addition to, deletion of
or deviation from the provisions of this Lease shall be binding unless in
writing and duly signed by the party against whom the same is sought to be
enforced.

                                     -41-
<PAGE>

     IN WITNESS WHEREOF, on the day and year first hereinabove written, the
undersigned have executed two (2) copies of this Lease under seal.

                                        LANDLORD
                                        --------

                                        International Telecommunications
                                           Satellite Organization
                                        3400 International Drive, N.W.
                                        Washington, D.C.  20008-3098

Attest:                                 By:    /s/ David T. Tudge
       -------------------------               ------------------
                                                      Signed

                                                   David T. Tudge
                                               ------------------
                                                      Typed

                                        Title:    Vice President and
                                                  Chief Financial Officer
                                                  -----------------------
[Seal]

                                        TENANT
                                        ------

                                        MIL 3, Inc.
                                        3400 International Drive, N.W.
                                        Pod 4L
                                        Washington, D.C.  20008-3098

Attest: /s/ Steven P. Bonarial (sp)     By:    /s/ Alain Cohen
        ------------------------------         ------------------
                                               Signed

                                                 Alain Cohen
                                               ------------------
                                                 Typed

[Corporate Seal]                        Title:   President
                                               ------------------

                                     -42-
<PAGE>

                                                         Exhibit A - Page 1 of 2

                                                                     MIL 3, Inc.

                                                                          Pod 2L

                               Atrium - 6 Diagram
<PAGE>

                                                         Exhibit A - Page 2 of 2

                                                                     MIL 3, Inc.

                                                                          Pod 4L

                                    Diagram
<PAGE>

                                                          Exhibit B, Page 1 of 3

                        PREOCCUPANCY WORK - MIL 3, INC.
                               INTELSAT BUILDING
             (PERTAINING TO RENTAL SPACES REQUIRING MODIFICATIONS)

Partitioning:         . Partitioning between suites and units to be slab to slab
                        and sound insulated.
                      . Partitioning to be constructed of 3 5/8" steel studs at
                        24 inches o.c. and 5/8" gypsum wallboard.
                      . Partitioning provided by landlord will be one linear
                        foot for each twelve (12) feet of rentable space.

Painting:             . Three coats flat finish paint building standard color
                        for all office partitioning.
                      . Interior doors to be stained building standard red oak
                        or equal.
                      . Hallways will be covered with building standard vinyl
                        wallcover.

Doors:                . Interior doors of rift cut red oak veneer, or equal with
                        glass sidelights, will be provided for each office in
                        the rentable space.
                      . Doors to be 2'-8" x 7'10" solid core, metal frame
                        equipped with building standard latch set.
                      . One suite entrance door will be provided for each tenant
                        with metal frame, equipped with building standard lock
                        set.

Floor Covering:       . Building standard carpet tile 18" x 18", special grey,
                        including 2-1/2 vinyl straight base will be provided.

Ceiling:              . Building standard suspended, acoustical tile ceiling
                        system provided.

Electrical:           . One 120 volt duplex wall electrical outlet will be
                        provided for each 150 square feet of rentable space.

Telephone:            . One telephone outlet will be provided for each 200
                        square feet of rentable space.

Outlets:              . Any special cable or amperage requirements are not
                        included, but will be provided by the landlord at
                        tenant's expense.

Lighting:             . One 2' x 4' recessed fluorescent lighting fixture with
                        parabolic lens per 80 square feet of rentable space.

Heating and           . Building standard heating and cooling for normal
Air Conditioning        office use and one thermostat for each 200 square
                        feet of rentable space is provided.
                      . Excess capacity, special controls and exhaust
                        requirements are not included, but will be provided by
                        landlord at tenant's expense.
<PAGE>

                                                          Exhibit B, Page 2 of 3

Window Covering:      . No window covering allowed.

Floor Loads:          . Floor loads are designed for 60 pounds per square foot
                        of live load and an additional allowance of 20 pounds
                        per square foot for partitioning.

Plumbing:             . Landlord will provide rough plumbing from nearest
                        plumbing stack to one location within space at landlords
                        option; 1,500 square feet of rentable space minimum.

Design Services:      . Consultation with landlord's space designer is provided
                        to prepare the documentation for tenant's space plan and
                        interior layout.
                      . Two (2) two- (2) hour planning sessions are provided and
                        one (1) major and two (2) minor revisions in the space
                        plans are allowed at no cost to tenant.

Allowance:            . Enumerated above are maximum allowance quantities to be
                        provided by landlord at no cost to tenant. There will be
                        no credits for unused portions of allowance quantities.

ABS Items:            . See Exhibit B, Page 3
<PAGE>

                                                          Exhibit B, Page 3 of 3

                        PREOCCUPANCY WORK - MIL 3, INC.
                                INTELSAT BUILDING

    Landlord will provide, at Landlord's sole expense, the following:

1.  One folding door in 4L;

2.  Millwork in existing 4L space necessary to modify existing counter and
    cabinets in connection with expansion of the Demo Room as illustrated. No
    ABS millwork will be provided by Landlord in 2L space;

3.  Two showers, two sinks, and plumbing associated with such showers and sinks
    in 2L;

4.  Computer Room air conditioner (three ton) in 2L;

5.  Shower exhaust fans, ducts in 2L;

6.  All Power Upgrades necessary to support Tenant's electrical requirements in
    both 2L and 4L as enumerated in Tenant's Letter of 17 December 1992
    (attached hereto as Exhibit E).

7.  Existing vinyl wall covering in the hallway within the new space in 4L shall
    be repaired or cleaned by Landlord where necessary.

8.  All carpet tiles within the new spaces in 4L and 2L shall be homogeneous in
    appearance.

9.  Landlord shall repaint Tenant's preexisting office space within six (6)
    months of taking occupancy under this Lease.

10. All thermostats controlling the climate within Tenant's demised premises
    shall be located somewhere within Tenant's demised premises where
    mechanically and commercially feasible. Landlord shall provide Tenant with a
    diagram or list of the thermostats and the areas which they control.

11. Landlord shall relocate the exit sign in the 4L conference room to a less
    obtrusive location.

     If there are any other ABS items which are necessary to construct the
office space as illustrated in Exhibit A, Landlord shall provide such items at
its sole expense.  Tenant reserves the right to alter the plans during the space
planning process.  If either Landlord or Tenant alters the plans (Exhibit A) in
a way that requires additional ABS items, such items shall be paid by the party
who alters the plans.
<PAGE>

                                                                       EXHIBIT C

                             RULES AND REGULATIONS
                             ---------------------

     The following rules and regulations have been formulated for the safety and
well-being of all the tenants of the Building.  Strict adherence to these rules
and regulations is necessary so that each and every tenant will enjoy a safe and
unannoyed occupancy in the Building.  Any violation of these rules and
regulations by any tenant which continues after notice from Landlord shall be
sufficient cause for termination of this Lease at the option of the Landlord.
In the event of a conflict between the terms of the Lease and the terms of these
Rules and Regulations, the terms of the Lease shall take precedence.

     Landlord may, upon request by any tenant, waive the compliance by such
tenant of any of the foregoing rules and regulations, provided that (i) no
waiver shall be effective unless signed by Landlord or Landlord's authorized
agent, (ii) any such waiver shall not relieve such tenant from the obligation to
comply with such rule or regulation in the future unless expressly consented to
by Landlord, and (iii) no waiver granted to any tenant shall relieve any other
tenant from the obligation of complying with the foregoing rules and regulations
unless such other tenant has received a similar written waiver from Landlord.

1.  The sidewalks, entrances, passages, courts, elevators, vestibules,
stairways, corridors or halls or other parts of the Building not occupied by any
tenant shall not be obstructed or encumbered by any tenant or used for any
purpose other than normal ingress and egress to and from the demised premises.
Landlord shall have the right to control and operate the public portions of the
Building and the grounds, and the facilities furnished for the common use of the
tenants, in such manner as Landlord deems best for the benefit of the tenants
generally.  No tenant shall permit the visit to the demised premises of persons
in such numbers or under such conditions as to interfere with the use and
enjoyment by other tenants of the entrances, corridors, elevators and other
public portions or facilities of the Building or of the grounds.

2.  Access to the building will be via recognised entrances only and tenants,
their employees, agents and guests will refrain from using emergency exits -
except in emergency situations.

3.  Employees of each tenant shall be provided by Landlord with a photo ID
access card which will facilitate entry to the common areas in the building.
Each tenant shall be responsible for returning all such cards to the Landlord on
termination of employment of any such person - or all cards upon termination of
the lease.  In the event of the loss, or failure to return any such card or
cards on termination of contract or lease, or for any other reason, tenant shall
pay Landlord all replacement costs involved.

4.  No signs, pictures, awnings or other projections shall be attached to the
outside walls of the Building without the prior written consent of Landlord.  No
drapes, blinds, shades or screens shall be attached to or hung in, or used in
connection with, any window or door of the
<PAGE>

demised premises, without the prior written consent of the Landlord, which
consent will not be unreasonably withheld.

5.  The lavatories and other plumbing fixtures shall not be used for any
purposes other than those for which they were constructed, and no sweepings,
rubbish, rags, or other substances shall be thrown therein.  All damages
resulting from any misuse of the fixtures shall be borne by the tenant who, or
whose employees, agents or guests, shall have caused the same.

6.  There shall be no marking, painting, drilling into or other form of
defacement or damage of any part of Building or grounds.  No boring, cutting or
stringing of wires shall be permitted without the prior written consent of
Landlord, which consent shall not be unreasonably withheld.  No tenant shall
construct, install, maintain, use or operate within, or on the outside of, the
Building or on the grounds, any electrical device, wiring or apparatus in
connection with a loudspeaker or other sound system.

7.  No animals, birds or pets of any kind shall be brought into or kept in or
about the Building or grounds.  Automobiles, motorcycles and bicycles may be
parked in the Building garage only in designated areas and only with the
specific prior approval of Landlord.  Automobiles, motorcycles and bicycles
parked without Landlord's approval, or not parked in designated areas, are
subject to removal without notice.

8.  No cooking shall be done or permitted by Tenant in the Building or on the
grounds, provided, however, that Tenant may install and maintain a microwave
oven, hot plate, coffee station, beverage and/or candy vending machines in the
demised premises for the convenience and exclusive use of Tenant's employees.
No tenant shall cause or permit any unusual or objectionable odors to originate
from the demised premises.

9.  No space in the Building shall be used for manufacturing.

10.  No tenant shall make, or permit to be made, any disturbing noises or
disturb or interfere with occupants of this Building or neighboring buildings or
premises or those having business with them, whether by the use of any musical
instrument, radio, talking machine or in any other way.  No tenant shall discard
anything into the public or common areas.

11.  No firearms or controlled substances shall be brought into or kept upon the
Building or grounds.
12.  No flammable, combustible or explosive fluid, chemical or substance shall
be brought or kept within the Building or upon the grounds.

13.  No additional locks or bolts of any kind shall be placed upon any of the
doors or other parts of the demised premises by any tenant, nor shall any
changes be made in existing locks or the machanisms thereof, without the prior
written consent of Landlord, which consent shall not be unreasonably withheld.
The doors leading to the corridors or main halls shall be kept closed during
business hours except as they may be used for normal ingress or egress.  Each
tenant shall, upon the termination of his tenancy, return to Landlord all keys
either furnished to, or otherwise procured by, such tenant, and in the event of
the loss of any such keys, such tenant shall pay to Landlord the cost of
replacing the locks.
<PAGE>

14.  All removals, or the carrying in or out of any safes, freight, furniture,
box, container or bulky matter of any description must take place during the
hours which Landlord or its agent may determine from time to time.  Landlord
reserves the right to inspect all materials to be brought into or out of the
Building or grounds, and to exclude from the Building and grounds all materials
which violates any of these Rules and Regulations or the Lease of which these
Rules and Regulations are a part.

15.  Any person employed by any tenant to perform janitorial services within the
demised premises must obtain Landlord's consent prior to commencing such work,
and such persons shall, while in or outside the Building, comply with all
instructions issued by Landlord or its representatives.  No tenant shall pay any
employees of Landlord or Landlord's agents to perform any work or services in or
outside the Building.

16.  No tenant shall purchase spring water, ice, coffee, soft drinks, towels, or
other products or services from any company or persons who violate the Building
regulations or disturb occupants of the Building.

17.  Landlord reserves the right to exclude from the Building and grounds at all
times any person who is not known or does not properly identify himself to the
Building management, receptionist or security guard on duty.  Landlord may, at
his option, require all persons admitted to or leaving the Building or grounds
to register with Building security guards.  Each tenant shall be responsible for
all persons for whom such tenant authorizes entry into the Building or upon the
grounds, and shall be liable to Landlord for all acts and omissions of such
persons.

18.  The premises shall not be used for lodging or sleeping or any immoral or
illegal purpose.

19.  The requirements of tenants will be acted upon only by the Landlord or
Landlord's designated representative.  Landlord's employees shall not be
requested to perform any work or do anything outside of their regular duties
unless authorized by the management of the Landlord.

20.  Canvassing, soliciting and peddling in the Building or upon the grounds is
prohibited and each tenant shall cooperate to prevent same.

21.  No water cooler or plumbing fixture may be installed by any tenant without
the prior written consent of the Landlord.

22.  There shall not be used in any space, or in the public or common halls of
the Building, either by any tenant or by others, any hand trucks, except those
equipped with rubber tires and side guards.

23.  Mats, trash or other objects shall not be placed in the public or common
corridors.

24.  There shall be no parking of vehicles or other obstructions placed in the
loading dock area.
<PAGE>

25.  Landlord reserves the right at any time, upon written notice to Tenant, to
make, eliminate, or modify these Rules and Regulations as in Landlord's sole
judgement may be necessary or desirable.

26.  Smoking is prohibited anywhere on INTELSAT property, including but not
limited to all offices, hallways, stairwells, garages," common areas, entrances,
parks and all surrounding grounds.  This regulation applies to all building
occupants, visitors and guests.
<PAGE>

                                                                       Exhibit D

                                    Diagram
<PAGE>

                       INTERNATIONAL TELECOMMUNICATIONS
                             SATELLITE ORGANIZATION

                       CERTIFICATE BY LANDLORD AND TENANT
                    AS TO DATE OF DELIVERY AND ACCEPTANCE OF
                         POSSESSION OF LEASED PREMISES

     Attached to and made a part of the Agreement of Lease, dated 18 June 1993,
as amended by Lease Amendment No. 2 dated 28 April 1995, entered into by and
between International Telecommunications Satellite Organization as Landlord, and
MIL 3, Inc. as Tenant.

     Landlord and Tenant do hereby declare that possession of the Additional
Office Space, 378 square feet located on the second level of Pod L of Phase II
of the INTELSAT Building, all as more fully described in Lease Amendment No. 2,
was accepted by Tenant on the 28th day of April, 1995.  The commencement date
for the term of lease for this Additional Office Space is hereby established as
1 May 1995, and the termination date shall be in accordance with Article 50,
Paragraph B of Lease Amendment No. 2.

<TABLE>
<CAPTION>
<S>                                          <C>
                                             LANDLORD

Attest:                                      INTELSAT

[sig]                                        /s/ Robert A. Lambert
-------------------------------------------  --------------------------------------------

                                             By:     Robert A. Lambert
                                                 ----------------------------------------
                                             Date:     15/5/95
                                                  ---------------------------------------
                                             TENANT

Attest:                                      MIL 3, Inc.

/s/ Marc A. Cohen                            /s/ Alain Cohen
-------------------------------------------  --------------------------------------------

                                             By:    Alain Cohen, President
                                                 ----------------------------------------
                                             Date:     5/14/95
                                                  ---------------------------------------
</TABLE>
<PAGE>

                             LEASE AMENDMENT NO. 3
                             ---------------------

     THIS LEASE AMENDMENT NO. 3 is made and entered into this 8th day of
September 1995, by and between the International Telecommunications Satellite
Organization ("Landlord") and MIL 3, Inc., a corporation organized and existing
under the laws of the State of Maryland ("Tenant") for the purpose of amending
the LEASE dated 18 June 1993 between said parties.

     WHEREAS, Landlord and Tenant entered into an Agreement of Lease on 18 June
1993 (the "Lease") for certain office space (the "demised premises") located on
the second and fourth levels of Pods L of Phase II of the office building
situated at 3400 International Drive, N.W., Washington, D.C. 20008-3098;

     WHEREAS, Landlord and Tenant entered into Lease Amendment No. 1 on 26
October 1994 to provide for the temporary lease by Landlord to Tenant of 1,580
rentable square feet on the second level of Pod L of Phase II;

     WHEREAS, Landlord and Tenant entered into Lease Amendment No. 2 on 28 April
1994 to provide for the temporary lease by Landlord to Tenant of 378 rentable
square feet on the second level of Pod L of Phase II;

     WHEREAS, Tenant desires to lease from Landlord, in addition to other leased
space described in the Lease, 1,958 rentable square feet located in the second
level of Pod L of Phase II, 7,768 rentable square feet located in the third
level of Pod L of Phase II and 105 rentable square feet located in the fourth
level of Pod L in Phase II (the "Additional office Space");

     WHEREAS, Landlord and Tenant are agreed upon the terms and conditions for
such lease of Additional Office Space; and

                                      -2-
<PAGE>

     WHEREAS, Landlord and Tenant are agreeable to amending the Lease to address
this matter;

     NOW THEREFORE, in consideration of the mutual promises of Landlord and
Tenant contained herein and for other good and valuable consideration, receipt
of which is hereby acknowledged, the parties hereto, intending to be legally
bound, agree to amend the Lease as follows:

1.  The following is ADDED to the end of Article 1:

          Effective 17 June 1998, the square footage measurements for Pod 2L
     shall be changed to 4,745 square feet of rentable area (2,260 + 2,485) and
     for Pod 4L shall be changed to 2,652 square feet of rentable area (1,432 +
     1,220).  In the event that there are any changes to the designation of fire
     corridors prior to 17 June 1998, the parties agree that the above changes
     in the square footage measurements may require further adjustments.

2.  In the penultimate line of Article 1, DELETE "or decrease".

3.  DELETE Article 2.A in its entirety and SUBSTITUTE the following therefor:

          The term of this Lease (hereinafter referred to as the "term") shall
     commence on 17 June 1993 ("Lease Commencement Date") and shall expire on 31
     December 1999 ("Lease Expiration Date").

                                      -3-
<PAGE>

4.  AMEND Article 2.B. by ADDING the words "(l January 2000 through 31 December
    2004)" after the words "additional period of five (5) years" which appear
    in the first sentence.

5.  AMEND Article 4.A. by ADDING the following after the second paragraph:

    Effective 17 June 1998, Tenant shall pay to Landlord a fixed monthly rental
    of Five Thousand Seven Hundred Thirty-three and 54/100 ($5,733.54) for the
    office spaces located in Pod 2L and Four Thousand Nine Hundred Fifty and
    40/100 ($4,950.40) for the office spaces located in Pod 4L due and payable
    in advance on the first (1st) day of each and every calendar month during
    the term of this Lease and any renewals of such term pursuant to Article 2.

6.  Article 8.B as follows:

    On lines 4 and 8, SUBSTITUTE "thirty (30) days" for "sixty (60) days".

    On line 9, SUBSTITUTE "one hundred eighty (180) days" for "ninety (90)
    days".

    DELETE subparagraph (d) and SUBSTITUTE "(d)" for "(e)".

    At the end of Paragraph B, ADD, "Within thirty (30) days of execution of
    any sublease or assignment made pursuant to this Article 8, Tenant shall
    submit to Landlord a copy of such sublease or assignment agreement."

                                      -4-
<PAGE>

7.  AMEND Article 8.C as follows:

    On line 4, DELETE "the notice from Tenant set forth in paragraph B above"
    and SUBSTITUTE "Tenant's Notice of Availability of Space (which need only
    describe the office space available)".

    On line 6, REPLACE the phrase "or portion thereof" with the parenthetical,
    (or portion thereof in floor-by-floor increments)".

    On Line 13, SUBSTITUTE "one hundred eighty (180) days" for "ninety (90)
    days".

8.  Reverse the order of Articles 8.B and 8.C such that "Recapture" becomes
    Paragraph B and "Tenant's Application (Assignment and Sublease)" becomes
    Paragraph C.

9.  DELETE Article 45 in its entirety and substitute the following therefor:

         In the event space in addition to the demised premises becomes
    available for commercial use at any time during the Term (including any
    extensions thereof) in Pod 7L, and Landlord does not require such
    additional space for its own use, Landlord shall provide written notice to
    Tenant of the availability of such additional space and Tenant shall have
    an option, exercisable by providing written notice to Landlord no later
    than ten (10) days from the date of receipt of Landlord's notice, to lease
    from Landlord, in addition to the demised premises, the additional space
    referenced in Landlord's notice; provided, however, that based upon
    Landlord's own need for office space Landlord may make its offering of

                                      -5-
<PAGE>

    space in Pod 7L conditional upon Tenant vacating office space within its
    leased premises located in Pods 2L, 3L and 4L.

10. A new Article 51 shall be ADDED as follows:

    51.  ADDITIONAL OFFICE SPACE

         The Additional Office Space described in paragraph A of this Article
    51 shall be governed by the terms and conditions of this Lease unless
    otherwise provided in this Article 51.

    A.  Demised Premises
        ----------------

         In addition to other leased space described herein, Landlord leases to
    Tenant, and Tenant hereby leases from Landlord, certain space outlined on
    Exhibit H attached hereto, and located on the second level of Pod L of
    Phase II of the INTELSAT Building, certain space outlined on Exhibit I
    attached hereto, and located on the third level of Pod L of Phase II of the
    INTELSAT Building, and certain space outlined in Exhibit J attached hereto,
    and located on the fourth level of Pod L of Phase II of the INTELSAT
    Building.  The parties hereto agree that the Additional Office Space
    constitutes 1,958 square feet of rentable area in Pod 2L, 7,768 square feet
    of rentable area in Pod 3L, and 105 square feet of rentable area in Pod 4L.
    This Additional Office Space shall be considered to be a portion of the
    "demised premises" as used throughout this Lease, during the term specified
    in Paragraph B of this Article 51, unless such meaning would be
    inconsistent with the provisions of this Article 51.  Tenant, at Tenant's
    sole expense, shall have the right to verify Landlord's measurement of the

                                      -6-
<PAGE>

    Additional Office Space, and shall also have the right to verify the
    necessity for, and location of, the additional fire corridor in Pod 3M.
    Adjustments to Tenant's square footage will be made if deemed appropriate
    by both parties.  Tenant hereby agrees that Landlord shall have the right,
    for the purposes of accommodating other tenants of Pod L or otherwise, to
    increase or decrease the dimensions, change the configuration, or to
    otherwise alter the common corridors; however, such alteration of the
    common areas shall not materially impair Tenant's use of the demised
    premises, and shall not increase the amount of common area attributable to
    Tenant as specified in this Article.

    B.  Term
        ----

         The term of lease for the Additional Office Space shall commence upon
    the date that Landlord notifies Tenant that Landlord's work (as set forth
    in Exhibits K and L of this Lease Amendment) is substantially complete;
    provided, however, that in the event that construction is substantially
    completed in either one of the new office spaces in 2L and 3L prior to
    substantial completion of construction in the other new office space,
    Landlord shall notify Tenant, and Tenant, at its sole option, shall be
    entitled to take occupancy of the substantially completed space.  If Tenant
    so elects to take occupancy, Tenant shall so inform Landlord in writing,
    and the Term for that office space shall commence upon the date that Tenant
    takes occupancy of the substantially completed space.  In such event,
    Tenant's total monthly rental shall not include rental for the location and
    square footage of the space which remains unfinished until such time as
    Landlord notifies Tenant that Landlord's work as set forth in Exhibits K

                                      -7-
<PAGE>

    and L of this Lease Amendment in the remaining new office space is
    substantially completed.  The term of the lease for the Additional office
    Space shall expire at midnight on 31 December 1999.

    C.  Rental
        ------

         (i)  Fixed Monthly Rental - In addition to the fixed monthly rental
    specified in Paragraph A of Article 4 of this Lease, Tenant shall pay to
    Landlord a sum of Two Thousand Two Hundred-two and 75/100 Dollars
    ($2,202.75) for the Additional Office Space in Pod 2L (1,958 rentable sq.
    ft.), Twelve Thousand Nine Hundred Forty-six and 67/100 Dollars ($12,946.67)
    for the Additional Office Space in Pod 3L (7,768 rentable sq. ft.), and One
    Hundred Ninety-six and 00/100 Dollars ($196.00) for the Additional Office
    Space in Pod 4L (105 rentable sq. ft.) due and payable in advance on the
    first day of each and every calendar month during the lease term specified
    in Paragraph B of this Article 51. Partial months shall be prorated.
    Landlord shall abate 50% of the fixed monthly rental for the Additional
    Office Space for each of the first twelve (12) months of the first lease
    year. Such abatement shall commence upon the date that Landlord notifies
    Tenant that all of Landlord's work as set forth in Exhibits K and L of this
    Lease Amendment is substantially complete.

         (ii) Operating Costs - In addition to the percentage of operating
    expenses specified in Article 4.B, Tenant shall pay to Landlord throughout
    the lease term specified in Paragraph B of this Article 51, as additional
    rental, 0.0331 (3.31%) (being the approximate and agreed upon proportion
    which the floor area of the Additional Office Space (9,831 rentable square

                                      -8-
<PAGE>

    feet) bears to the architectural and engineering (A&E) design figure for
    total area of the Building) (296,733 rentable square feet) of the Actual
    Operating Expenses.

         In the event Tenant obtains and exercises an option to take occupancy
    of the new office space in Pod 2L prior to taking occupancy of the new
    office space in Pod 3L, Tenant shall pay to Landlord until the date that
    Landlord notifies Tenant that all of Landlord's work as set forth in
    Exhibits K and L of this Lease Amendment is substantially complete, as
    additional rental, 0.0066 or (0.66%) (being the approximate and agreed upon
    proportion which the floor area of the new office space in Pod 2L (1,958
    rentable square feet) bears to the architectural and engineering (A&E)
    design figure for total area of the Building) (296,733 rentable square
    feet) of the Actual Operating Expenses.  once such notice is provided by
    Landlord to Tenant, Tenant shall begin paying to Landlord, as additional
    rental, 0.0331 (3.31%), in lieu of the 0.0066 (.66%) of the Actual
    operating Expenses.

          In the event Tenant obtains and exercises an option to take occupancy
    of the new office space in Pod 3L prior to taking occupancy of the new
    office space in Pod 2L, Tenant shall pay to Landlord until the date that
    Landlord notifies Tenant that all of Landlord's work as set forth in
    Exhibits K and L of this Lease Amendment is substantially complete, as
    additional rental, 0.0262 (2.62%) (being the approximate and agreed upon
    proportion which the floor area of the new office space in Pod 3L (7,768
    rentable square feet) bears to the architectural and engineering (A&E)
    design figure for total area of the Building) (296,733 rentable square
    feet) of the Actual Operating Expenses.  Once such notice is provided by

                                      -9-
<PAGE>

    Landlord to Tenant, Tenant shall begin paying to Landlord, as additional
    rental, 0.0331 (3.31%), in lieu of the 0.0262 (2.62%) of the Actual
    Operating Expenses.

         The projected Operating Expenses for 1995 are estimated to be Four
    Dollars and Forty Seven Cents ($4.47) per square foot of total area of the
    Building for 1995.

    D.  Security Deposit
        ----------------

         Concurrently with Tenant's execution of this Lease Amendment No. 3,
     Tenant shall deposit with Landlord the sum of Thirty Thousand Six Hundred
     Ninety and 84/100 Dollars ($30,690.84), less amounts already deposited with
     Landlord under Amendment No. 1 ($1,580.00) and Amendment No. 2 ($378.00);
     $15,345.42 of which shall be used as payment of the first month's rent
     actually due Landlord and the remaining portion of which shall be used as
     security for the full and faithful performance by Tenant of each and every
     term, provision, covenant, and condition of this Lease.  Landlord shall
     grant to Tenant an annual rental credit equal to 2.30% interest on the
     security deposited with Landlord pursuant to this Article 51.D.  The
     security deposited with Landlord pursuant to this Article 51.D shall be in
     addition to the security deposit previously paid by Tenant pursuant to
     Article 6 of the Lease and shall be subject to the provisions of Article 6
     of this Lease.

     E.  Preoccupancy Work
         -----------------

          Landlord, at its own expense, will provide design services and
     construct the demised premises and Additional Office Space in accordance

                                     -10-
<PAGE>

     with the provisions set forth in Exhibits K and L attached hereto and made
     a part hereof.  Landlord shall have no obligation to make any alterations,
     additions, or improvements to the demised premises or the Additional office
     Space except as set forth in Exhibits K and L; provided, however, Tenant
     may, at its own expense, substitute a higher grade item for that of a
     building-standard item (e.g., door locks) in which case Tenant shall
     receive a credit from INTELSAT for the cost of the building-standard item
     being replaced.  Subject to the need to minimize remobilization costs,
     Tenant shall have the right to specify the scheduling of construction in
     the different office spaces, to minimize any disruption to Tenant's
     business.

     F.  Parking Option
         --------------

          Tenant shall have the right, on a one-time offer, to lease from
     Landlord six (6) parking permits in the Building garage in addition to
     those specified in Article 46.  This parking option may be exercised by
     Tenant only upon the date on which Tenant executes this Lease Amendment No.
     3.  The additional parking permits shall be leased by Tenant at prevailing
     market rates, currently $80 per space, per month.

11.  A new Exhibit H is attached hereto and incorporated herein.

12.  A new Exhibit I is attached hereto and incorporated herein.

13.  A new Exhibit J is attached hereto and incorporated herein.

14.  A new Exhibit K is attached hereto and incorporated herein.

15.  A new Exhibit L is attached hereto and incorporated herein.

                                     -11-
<PAGE>

     IN WITNESS WHEREOF, on the day and year first hereinabove written, the
undersigned have executed two copies of this Lease Amendment No. 3.
<TABLE>
<CAPTION>
                                              LANDLORD
                                              --------
<S>                                           <C>
                                              International Telecommunications Satellite
                                              Organization
                                              3400 International Drive, N.W.
                                              Washington, D.C.  20008-3098

Attest:     /s/ R. A. Lambert                 By:     /s/ David T. Tudge
       -----------------------------------       -----------------------------------------
                  Signed                                      Signed

                                                          David T. Tudge
                                              --------------------------------------------
                                              Title:  Vice President & Chief
                                                      Financial Officer

                                              TENANT
                                              ------

                                              MIL 3, Inc.
                                              3400 International Drive, N.W.
                                              Pod 4L
                                              Washington, D.C.  20008-3098

Attest:     [sig]                             By:     /s/ Alain Cohen
       -----------------------------------       -----------------------------------------
                     Signed                                Signed

                                              --------------------------------------------
                                                               Typed

                                              Title:
                                                    --------------------------------------
</TABLE>

                                     -12-
<PAGE>

                   A new Exhibit H shall be ADDED as follows:

                                                           EXHIBIT H

                       PLAN OF ADDITIONAL SPACE IN POD 2L

                                     -13-
<PAGE>

                   A new Exhibit I shall be ADDED as follows:

                                                           EXHIBIT I

                       PLAN OF ADDITIONAL SPACE IN POD 3L

                                     -14-
<PAGE>

                   A new Exhibit J shall be ADDED as follows:

                                                           EXHIBIT J

                       PLAN OF ADDITIONAL SPACE IN POD 4L

                                     -15-
<PAGE>

                  STANDARD WORK LETTER FOR TENANT IMPROVEMENTS

                                INTELSATBUELDING

                                    PHASE II

<TABLE>
<CAPTION>
<S>                  <C>
Partitioning:        .    Partitioning between suites and units to be slab to slab and sound insulated.

                     .    Partitioning to be constructed of 3 5/8" steel studs at 24 inches o.c. and 5/8' gypsum

Painting:            .    Three coats eggshell finish paint building standard color for all office partitioning.

                     .    Interior doors to be stained building standard red oak or equal.

Doors:               .    Interior doors of rift cut red oak veneer, or equal with glass sidelights, will be provided for each
                          office in the rentable space.

                     .    Doors to be 2'-8" x 7'10" solid core, metal frame equipped with building standard latch set.
                          One suite entrance door will be provided for each tenant with metal frame, equipped with building
                          standard lock set.

Floor                .    Building standard carpet tile 18" x 18", special grey, including 2% vinyl straight base will be
Covering:                 provided.

Ceiling:             .    Building standard suspended, acoustical tile ceiling system provided.

Electrical:          .    One 120 volt duplex wall electrical outlet will be provided for each 150 square feet of rentable
                          space.

Telephone:           .    One telephone outlet will be provided for each 200 square feet of rentable space.

Outlets:             .    Any special cable or amperage requirements are not included, but will be provided by the landlord at
                          tenant's expense.

Lighting:            .    One 2' x 4' recessed fluorescent lighting fixture with parabolic lens per 80 square feet of rentable
                          space.

Heating and Air      .    Building standard beating and cooling for normal office use and one thermostat for each 200 square
Conditioning:             feet of rentable space is provided.

                     .    Excess capacity, special controls and exhaust requirements are not included, but will be provided by
                          landlord at tenant's expense.

Window Covering      .    No window covering provided by Landlord.

Floor Loads:         .    Floor loads am designed for 60 pounds per square foot of live load and an additional allowance of 20
                          pounds per square foot for partitioning.

Plumbing:            .    Landlord will provide rough plumbing from nearest plumbing stack to one location within space at
                          landlords option; 1,500 square feet of rentable space minimum.

Design Services:     .    Consultation with landlord's space designer is provided to prepare the documentation for tenant's
                          space plan and interior layout.

                     .    Two (2) two- (2) hour planning sessions are provided and one (1) major and two (2) minor revisions
                          in the space plans are allowed at no cost to tenant.

Allowance            .    Enumerated above are maximum allowance quantities to be provided by landlord at no cost to tenant.
                          There will be no credits for unused portions of allowance quantities.
</TABLE>

                                     -16-
<PAGE>

04 May 1999

Mr. Joseph Greeves
Chief Financial Officer
MIL-3, Inc.
3400 International Drive, N.W.
Suite 4L
Washington, D.C.  20008

                               VIA HAND DELIVERY
                               -----------------

Re:   Lease Amendment No. 4

Dear Mr. Greeves:

Enclosed for your files is one original, fully executed Amendment to Lease 4
INTEL-L-1433 (Lease Amendment No. 4), entered into by and between International
Telecommunications Satellite Organization as Landlord, and MIL-3, Inc. as
Tenant.  A copy of the Delivery & Acceptance Certificate is also enclosed.

If you have any questions, please call me at (202) 944-8235.

Sincerely,

CHARLES E. SMITH COMMERCIAL REALTY

/s/ Karen K. Wilson

Karen K. Wilson, RPA
Lease Administrator

/kkw
Enc. (2)

cc:  R. Lambert, INTELSAT
     C. Diehl, C.E. Smith
     Lease File

                                     -17-
<PAGE>

                             LEASE AMENDMENT NO. 4
                             ---------------------

     THIS LEASE AMENDMENT NO. 4 is made this 28th day of April, 1999, by and
between the International Telecommunications Satellite Organization
("Landlord"), an international organization, and MIL 3, Inc., a corporation
organized and existing under the laws of the State of Maryland ("Tenant") for
the purpose of amending the LEASE dated 18 June 1993 between said parties.

     WHEREAS, Landlord and Tenant entered into an Agreement of Lease on 18 June
1993 (the "Lease") for certain office space (the "demised premises") located on
the second and fourth levels of Pod L of Phase II of the office building
situated at 3400 International Drive, N.W., Washington, D.C. 20008-3098;

     WHEREAS, Landlord and Tenant entered into Lease Amendment No. 1 on 26
October 1994 to provide for the temporary lease by Landlord to Tenant of certain
office space on the second level of Pod L of Phase II;

     WHEREAS, Landlord and Tenant entered into Lease Amendment No. 2 on 28 April
1995 to provide for the temporary lease by Landlord to Tenant of certain office
space on the second level of Pod L of Phase II;

     WHEREAS, Landlord and Tenant entered into Lease Amendment No. 3 on 8
September 1995 to extend the term of the Lease, to provide for the lease by
Landlord to Tenant of certain office space on the second, third and fourth
levels of Pod L of Phase II, and to amend other provisions of the Lease;

     WHEREAS, Tenant desires to lease from Landlord, in addition to other leased
space described in the Lease, 3,987 rentable square feet located in the third
level of Pod M of Phase II (the "Additional office Space");

                                     -18-
<PAGE>

     WHEREAS, Landlord and Tenant are agreed upon the terms and conditions for
such lease of Additional Office Space; and

     WHEREAS, Landlord and Tenant are agreeable to amending the Lease to address
this matter;

     NOW THEREFORE, in consideration of the mutual promises of Landlord and
Tenant contained herein and for other good and valuable consideration, receipt
of which is hereby acknowledged, the parties hereto, intending to be legally
bound, agree to amend the Lease as follows:

1.  A new Article 52 shall be ADDED as follows:

    52.  ADDITIONAL OFFICE SPACE

         The Additional Office Space described in paragraph A of this Article
    52 shall be governed by the terms and conditions of this Lease unless
    otherwise provided in this Article 52.

          A.  Demised Premises
              ----------------

               In addition to other leased space described herein, Landlord
          leases to Tenant, and Tenant hereby leases from Landlord, certain
          space outlined on Exhibit M attached hereto, and located on the third
          level of Pod M of Phase II of the INTELSAT Building.  The parties
          hereto agree that the Additional office Space constitutes 3,987 square
          feet of rentable area.  This Additional Office Space shall be
          considered to be a portion of the "demised premises" as used
          throughout this Lease, during the term specified in Paragraph B of
          this Article 52, unless such meaning would be inconsistent with the
          provisions of this Article 52.  Tenant, at Tenant's sole expense,
          shall have the right to verify Landlord's measurement of the
          Additional Office Space.  Adjustments to Tenant's square footage will
          be made if deemed appropriate by both parties.  Tenant hereby agrees
          that Landlord shall have the right, for the purposes of accommodating
          other tenants of Pod M or otherwise, to increase or decrease the
          dimensions, change the configuration, or to otherwise alter the common
          corridors; however, such alteration of the common areas shall not
          materially impair Tenant's use of the demised premises, and shall not
          increase the amount of common area attributable to Tenant as specified
          in this Article.

                                     -19-
<PAGE>

          B.  Term
              ----

               The term of lease for the Additional Office Space shall commence
          upon 23 January 1999 and shall expire at midnight on 31 December 1999.

          C.  Rental
              ------

               (i) Fixed Monthly Rental - In addition to the fixed monthly
          rental specified in Paragraph A of Article 4 of this Lease, Tenant
          shall pay to Landlord

                    (a) for the period 23 January 1999 to 8 April 1999, a sum of
               Five Thousand Nine Hundred Eighty and 50/100 ($5,980.50) per
               month, and

                    (b) for the period 9 April 1999 until expiration of this
               Lease, a sum of Six Thousand Twenty Three and 69/100 Dollars
               ($6,023.69) per month, due and payable in advance on the first
               day of each and every calendar month during the lease term
               specified in Paragraph B of this Article 52.  Payment for the
               first month under this Lease Amendment No. 4 shall be paid
               concurrently with Tenant's execution thereof.  Partial months
               shall be prorated.

               (ii) Operating Costs - In addition to the percentage of operating
          expenses specified in Article 4.B, Tenant shall pay to Landlord, for
          the period 9 April 1999 until expiration of this Lease, as additional
          rental, 0.0134 (1.34%) (being the approximate and agreed upon
          proportion which the floor area of the Additional Office Space (3,987
          rentable square feet) bears to the architectural and engineering (A&E)
          design figure for total area of the Building) (296,733 rentable square
          feet) of the Actual Operating Expenses.

          D.  Security Deposit
              ----------------

               Concurrently with Tenant's execution of this Lease Amendment No.
          4, Tenant shall deposit with Landlord the sum of Six Thousand Twenty
          Three and 69/100 Dollars ($6,023.69), which shall be used as security
          for the full and faithful performance by Tenant of each and every
          term, provision, covenant, and condition of this Lease.  The security
          deposited with Landlord pursuant to this Article 52.D shall be in
          addition to the security deposit previously paid by Tenant pursuant to
          the Lease and shall be subject to the provisions of Article 6 of this
          Lease.

          E.  Preoccupancy Work
              -----------------

               Notwithstanding any other provision of this Lease, the Additional
          Office Space shall be provided by Landlord to Tenant in "AS IS"
          condition.

                                     -20-
<PAGE>

          F.  Parking Option
              --------------

               Tenant shall have the right, on a one-time offer, to lease from
          Landlord three (3) parking permits in the Building garage in addition
          to those specified in Article 46 and Article 51.F.  This parking
          option may be exercised by Tenant only upon the date on which Tenant
          executes this Lease Amendment No. 4.  The additional parking permits
          shall be leased by Tenant at prevailing market rates, currently $80
          per space, per month.

2.  A new Exhibit M is attached hereto and incorporated herein.

          IN WITNESS WHEREOF, on the day and year first hereinabove written, the
undersigned have executed two copies of this Lease Amendment No. 4.

<TABLE>
<CAPTION>
<S>                                          <C>
                                             LANDLORD
                                             --------

                                             International Telecommunications Satellite
                                             Organization

                                             3400 International Drive, N.W.
                                             Washington, D.C.20008-3098

Attest:     /s/ R. Lambert                   By:     /s/ Joseph Corbett
       ----------------------------------       -----------------------------------------
                Signed                                       Signed

                                                            Joseph Corbett
                                             --------------------------------------------
                                             Title:  Vice President &
                                                     Chief Financial Officer

                                             TENANT
                                             ------

                                             MIL 3, Inc.
                                             3400 International Drive, N.W.
                                             Pod 4L
                                             Washington, D.C.20008-3098

Attest:     /s/ A. Dalton                    By:     /s/ Joseph F. Greeves
       ----------------------------------       -----------------------------------------
                                                             Signed

                                                          Joseph F. Greeves
                                             --------------------------------------------
                                                                Typed
                                             Title:  Chief Financial Officer
</TABLE>

                                     -21-
<PAGE>

                                                EXHIBIT M

                                  Mil 3 POD-3M

                                   3,987 s.f.

                                     -22-
<PAGE>

                        INTERNATIONAL TELECOMMUNICATIONS

                             SATELLITE ORGANIZATION

                       CERTIFICATE BY LANDLORD AND TENANT

                    AS TO DATE OF DELIVERY AND ACCEPTANCE OF

                         POSSESSION OF LEASED PREMISES

     Attached to and made a part of the Agreement of Lease, dated 18 June 1993,
as amended by Lease Amendment No. 4, dated 08 April 1999, entered into by and
between International Telecommunications Satellite Organization as Landlord, and
MIL 3, Inc. as Tenant.

     Landlord and Tenant do hereby declare that possession of the Additional
Office Space, 3,987 square feet located on the third level of Pod M of Phase If
of the INTELSAT Building, all as more fully described in Lease Amendment No. 4,
was accepted by Tenant on the 23rd day of January 1999.  The commencement date
for the term of lease for this Additional Office Space is hereby established as
23 January 1999, and the termination date shall be in accordance with Article
52, Paragraph B of Lease Amendment No. 4.

     In addition, Tenant acknowledges the exercising of their right to lease
three (3) additional parking spaces within Phase II of the INTELSAT Building
Parking Garage.

<TABLE>
<CAPTION>
<S>                                          <C>
                                             LANDLORD

                                             INTELSAT

Attest:                                      By:     /s/ Robert A. Lambert
                                                -----------------------------------------
                                                         Robert A. Lambert, RPA, FMA
/s/ Karen K. Wilson
-------------------------------------------  Date:     13 April 1999
                                                  ---------------------------------------

                                             TENANT

                                             MIL 3, Inc.

Attest:                                      By:    /s/ Joseph F. Greeves
                                                -----------------------------------------
                                                       Joseph F. Greeves
/s/ A. Dalton
-----------------------------------------    Date:     4/12/99
                                                  ---------------------------------------
</TABLE>
                                     -23-
<PAGE>

12 October 1999

Mr. Joseph Greeves
Chief Financial Officer
MIL-3, Inc.
3400 International Drive, N.W.
Suite 4L
Washington, D.C.  20008                                 VIA HAND DELIVERY
                                                        -----------------

Re:   Lease Amendment No. 5

Dear Mr. Greeves:

Enclosed for your files is one original, fully executed Amendment to Lease
#INTEL-L- 1433 (Lease Amendment No. 5), entered into by and between
International Telecommunications Satellite Organization as Landlord, and MIL-3,
Inc. as Tenant.

If you have any questions, please call me at (202) 944-8235.

Sincerely,

CHARLES E. SMITH COMPANIES

/s/ Karen K. Wilson

Karen K. Wilson, RPA
Lease Administrator

/kkw
Enc.

cc:  Robert Lambert, INTELSAT
     John Navolio, C.E. Smith
     CES Lease File

                                     -24-
<PAGE>

                             LEASE AMENDMENT NO. 5
                             ---------------------

     THIS LEASE'AMENDMENT NO. 5 is made this 7th day of September, 1999, by and
                                             ---        ---------------
between the International Telecommunications Satellite Organization
("Landlord"), an international organization, and MIL 3, Inc., a corporation
organized and existing under the laws of the State of Maryland ("Tenant") for
the purpose of amending the LEASE dated 18 June 1993 between said parties.

     WHEREAS, Landlord and Tenant entered into an Agreement of Lease on 18 June
1993 (the "Lease") for certain office space (the "demised premises") located on
the second and fourth levels of Pod L of Phase II of the office building
situated at 3400 international Drive, N.W., Washington, D.C.  20008-3098;

     WHEREAS, Landlord and Tenant entered into Lease Amendment No. 1 on 26
October 1994 to provide for the temporary lease by Landlord to Tenant of certain
office space on the second level of Pod L of Phase II;

     WHEREAS, Landlord and Tenant entered into Lease Amendment No. 2 on 28 April
1995 to provide for the temporary lease by Landlord to Tenant of certain office
space on the second level of Pod L of Phase II;

     WHEREAS, Landlord and Tenant entered into Lease Amendment No. 3 on 8
September 1995 to extend the term of the Lease, to provide for the lease by
Landlord to Tenant of certain office space on the second, third and fourth
levels of Pod L of Phase II, and to amend other provisions of the Lease;

     WHEREAS, Landlord and Tenant entered into Lease Amendment No. 4 on 28 April
1999 to provide for the lease by Landlord to Tenant of certain office space on
the third level of Pod M of Phase II;

     WHEREAS, Tenant desires to extend the initial term of the Lease for one
year beyond the Lease Expiration Date of 31 December 1999, and Landlord is
agreeable to that extension.

     NOW THEREFORE, in consideration of the mutual promises of Landlord and
Tenant contained herein and for other good and valuable consideration, receipt
of which is hereby acknowledged, the parties hereto, intending to be legally
bound, agree to amend the Lease as follows:

1.  A new Article 53 shall be ADDED as follows:

    53.  ONE YEAR EXTENSION
         ------------------

         Notwithstanding Paragraph A of Article 2 and Paragraph B of Article 52
    to this Lease, and without prejudice to Paragraph B of Article 2 ("Option
    to Renew") to this Lease, the initial-term of this Lease shall be extended
    for one year and shall expire at midnight on 31 December 2000.  The fixed
    monthly rental shall be adjusted for the calendar year commencing on

                                     -25-
<PAGE>

     January 1, 2000 and on January 1 for each succeeding calendar year in
     accordance with Article 5 to this Lease.

     IN WITNESS WHEREOF, on the day and year first hereinabove written, the
undersigned have executed two copies of this Lease Amendment No. 5.

<TABLE>
<CAPTION>
<S>                                          <C>
                                             LANDLORD
                                             --------
                                             International Telecommunications Satellite
                                             Organization

                                             3400 International Drive, N.W.
                                             Washington, D.C.  20008-3098

Attest:

/s/ R. A. Lambert                            By:   /s/ Joseph Corbett
-------------------------------------------     ----------------------------------------
      Signed                                             Signed

                                                            Joseph Corbett
                                             --------------------------------------------
                                             Title:  Vice President &
                                                     Chief Financial Officer

                                             TENANT
                                             ------

                                             MIL 3, Inc.
                                             3400 International Drive, N.W.
                                             Pod 4L
                                             Washington, D.C.  20008-3098
Attest:

/s/ A. Dalton                                By:      /s/  Joseph F. Greeves
-------------------------------------------     ------------------------------------------
     Signed                                                   Signed

                                                          Joseph F. Greeves
                                              --------------------------------------------
                                                                Typed

                                              Title:  Chief Financial Officer
</TABLE>
                                     -26-<PAGE>
                                                                   EXHIBIT 10.22

                               SUBLEASE AGREEMENT

     This Sublease Agreement ("Sublease") is made and entered into as of
November 1, 1997, by and between WJLA-TV, a division of Allbritton
Communications Company ("WJLA") and MIL 3, Inc. ("MIL 3").

     WHEREAS, WJLA, as tenant, is a party to that certain Lease Agreement
("Master Lease") dated as of November 3, 1986 (a redacted copy of which is
attached hereto as Exhibit 1) wherein WJLA has leased space from the
International Telecommunications Satellite Organization ("Intelsat") in its
headquarters building ("Building") located at 3007 Tilden Street, NW,
Washington, D.C. 20008; and

     WHEREAS, MIL 3 desires to sublease from WJLA a portion of the space leased
to WJLA under the Master Lease;

     NOW, THEREFORE, in consideration of the mutual promises contained herein
and for other good and valuable consideration, receipt of which is hereby
acknowledged, the parties hereto, intending to be legally bound, agree as
follows:

        1.  Subleased Premises.  MIL 3 hereby subleases from WJLA and WJLA
            ------------------
subleases to MIL 3 for the Sublease Term defined herein a portion of the space
leased by WJLA under the Master Lease consisting of the Sixth (6th) Floor, Pod P
(excluding the link area between Pod P and Pod N) measuring approximately 7,074
rentable square feet as shown on Exhibit 2, attached hereto and incorporated
herein ("Subleased Premises"). MIL 3 shall have access to and occupy the
Subleased Premises. WJLA shall provide janitorial services (including trash
collection) and basic utilities, but shall not provide parking and security
services. Intelsat shall not provide additional parking or services to MIL 3.

        2.  Sublease Term.  The Sublease Term shall commence on November 1, 1997
            -------------
and terminate on October 31, 2002 ("Termination Date"); provided, however, that:
(a) MIL 3 may accelerate the expiration date at any time and without penalty
upon six (6) months' prior written notice to WJLA; and (b) WJLA may accelerate
the expiration date beginning November 1, 1999 without penalty upon six (6)
months' prior written notice to MIL 3 with such expiration date to be effective
no earlier than May 1, 2000.

        3.  Alterations.  MIL 3 will not make or permit anyone to make any
            -----------
alterations, additions or improvements, structural or otherwise (hereinafter
referred to as "Alterations"), in or to the demised premises or the Building,
without the prior written consent of WJLA, which consent shall not be
unreasonably withheld. All Alterations made by MIL 3 shall be at MIL 3's sole
cost and expense, and MIL 3 will indemnify and hold WJLA harmless from and
against any and all liens, claims, or damages which may arise by reason of the
making of any Alterations. Any Alterations approved by WJLA may be left in place
at the expiration of the Sublease. If any Alteration is made without the prior
written consent of WJLA, MIL 3 shall at the expiration of the Sublease, at its
sole cost and expense, remove such Alteration and restore the Sublease Premises
to its original condition, except to the extent that WJLA, in its reasonable
discretion, determines that said Alterations may remain. If MIL 3 fails to
perform such work
<PAGE>

within thirty (30) days after the expiration of the Sublease, WJLA may arrange
to have such Alteration removed at MIL 3's expense.

        4.  Base Rental Rate.  MIL 3's monthly rent shall be the rent WJLA is
            ----------------
currently paying attributed to the Subleased Premises ($14,737.50 based upon an
annual rate of $25 per rentable square foot) which includes operating expenses
and real estate taxes, if any, with such rent payable on the first day of each
month of the Sublease Term. At the beginning of the second lease year (November
1, 1998) and at the beginning of each subsequent lease year of the Sublease, MIL
3's monthly rent shall increase five (5) percent.

        5.  Condition of Subleased Premises.  MIL 3 acknowledges that the
            -------------------------------
Subleased Premises are acceptable on an "as-is" basis with no build-out offset
or rental abatement. WJLA shall provide no other work or services to MIL 3
through the Sublease Term except as provided in this Sublease.

        6.  Access.  MIL 3 shall have access to the Building and Sublease
            ------
Premises twenty-four (24) hours a day, seven (7) days a week, 365 days per year.

        7.  Building Services.  WJLA, through the Master Lease, represents that
            -----------------
Intelsat will maintain heating, ventilation and air conditioning services as
provided in the Master Lease. WJLA shall maintain the supplemental HVAC
equipment installed in the Subleased Premises.

        8.  Security Deposit.  MIL 3 shall deliver to WJLA simultaneously with
            ----------------
the execution hereof the sum of $14,737.50 ("Security Deposit"). WJLA, as soon
as practicable thereafter, shall deposit the Security Deposit in a separate
federally insured interest-bearing savings account with interest credited to MIL
3. Provided MIL 3 has complied with all the terms and conditions of this
Sublease and no MIL 3 Event of Default has then occurred or is occurring, WJLA
shall return the Security Deposit fifteen (15) days following the later of the
last day of the Sublease or the date on which the work required by Section 3 is
completed, if any.

        9.  Insurance.  MIL 3 shall obtain and maintain in effect at all times
            ---------
during the term of this Sublease a policy of comprehensive public liability
insurance, naming WJLA and Intelsat as additional insureds, protecting MIL 3,
WJLA and Intelsat against any liability for bodily injury, death or property
damage occurring upon, in or about any part of the Subleased Premises arising
from any of the items set forth in this Paragraph against which MIL 3 is
required to indemnify WJLA, with such policies to afford protection (1) with
respect to bodily injury or death to the limit of not less than One Million
Dollars ($1,000,000) to any one person and to the limit of not less than Three
Million Dollars ($3,000,000) with respect to any one accident, and (ii) with
respect to damage to the property of any one owner to the limit of not less than
Five Hundred Thousand Dollars ($500,000). Such insurance policies shall be
issued by responsible insurance companies licensed to do business in the
District of Columbia. A certificate of insurance evidencing the issuance of such
insurance policy, together with evidence of payment of premiums thereon, shall
be delivered to WJLA upon WJLA's written request prior to the Commencement Date
and at least thirty (30) days before the expiration date of any policy evidenced
by a certificate previously furnished.

                                      -2-
<PAGE>

        10.  Damages.  MIL 3 shall be responsible for any and all damages which
             -------
occur in the Sublease Premises except to the extent they result from acts of God
or any actions taken by Intelsat or WJLA or any other tenant of the Building.
MIL 3 shall, on the Termination Date, at its own expense, remove all signs and
advertising devices and repair any damage caused by such removal.

        11.  Representations and Warranties of WJLA.  WJLA represents and
             --------------------------------------
warrants to MIL 3 that: (A) the Master Lease is valid and existing, in full
force and effect and Exhibit 1 contains a true and correct copy of the Master
Lease as amended to date (exclusive of confidential information and economic
terms and conditions) and there are no other agreements with Intelsat with
respect to the Sublease Premises; (B) there are no existing defaults on the part
of Intelsat or WJLA with respect to the Master Lease; (C) Intelsat does not hold
any claim against WJIA; and (D) there are and will be no contracts for service
or otherwise which expressly or impliedly are or will be binding upon MIL 3 or
the Sublease Premises.

        12.  Representations, Warranties and Covenants of MIL 3.
             --------------------------------------------------

        12.1.  Representations, Warranties.  MIL 3 acknowledges that MIL 3 has
               ---------------------------
received a copy of the Master Lease (with certain provisions thereof redacted by
WJLA) and agrees that this Sublease is subject to all of the terms and
conditions of the Master Lease, except as specifically redacted exempted or
modified herein.

        12.2.  Covenants.  MIL 3 covenants and agrees to: (A) indemnify and hold
               ---------
harmless WJLA from MIL 3s failure to comply with the terms and conditions of the
Master Lease or this Sublease; (B) permit Intelsat and WJLA (and their agents or
representatives), who will use reasonable, good faith efforts to minimize
disruption to MIL 3's business, upon proper notice, except no prior notice is
required in the event of an emergency to enter and inspect the Sublease Premises
during normal business hours to verify MIL 3's compliance with the Sublease; (C)
furnish WJLA with copies of all renewals of insurance and all other obligations
relating to Master Lease and/or consent obligations; (D) inform WJLA in writing
of all material contacts with Intelsat and send WJLA copies of all material
correspondence with Intelsat; (E) permit WJLA to participate in any meetings
with Intelsat concerning the Master Lease; (F) subject to the provisions of
Paragraph 3, return the Sublease Premises to WRA on the Termination Date in the
condition received, reasonable wear and tear excepted. MIL 3 shall not commit or
permit to be committed on the Sublease Premises any act or omission which shall
violate any term or condition of the Master Lease or assign or sublease the
Sublease Premises except as otherwise provided for in this Sublease.

        13.  Master Lease; Consent.
             ---------------------

        13.1.  Incorporation by Reference; Conflicts. Capitalized terms used in
               -------------------------------------
this Sublease, and not otherwise defined are used with the meaning given such
terms in the Master Lease. Except as otherwise provided in this Sublease, all of
the covenants, agreements, terms, provisions and conditions of the Master Lease
insofar as they relate to the Sublease Premises are incorporated herein and made
a part of hereof. Except where otherwise specifically provided in this Sublease,
the obligations of WJLA as tenant under the Master Lease shall be binding upon
MIL 3 during the Sublease Term, but only with respect to the Sublease Premises,
with the same

                                      -3-
<PAGE>

force and effect as if herein set forth at length and with respect thereto the
words "Landlord" and "Tenant" as used in the Master Lease, shall be deemed to
refer to WJLA and MIL 3 respectively. In the event of a conflict between this
Sublease and the Master Lease, the Master Lease shall prevail.

        13.2.  Liability and Indemnity.  WJLA shall not be liable with respect
               -----------------------
to the Sublease Premises under the Master Lease or this Sublease for any breach,
defaults, negligence or willful omissions by Intelsat, its agents, successors or
assigns, but shall be liable only for its own acts, negligence or willful
omissions, or those of its agents, successors or assigns, and shall indemnify
and save harmless MIL 3 from same. MIL 3 shall indemnify and save harmless WJLA
and Intelsat with respect to personal injury, death or property damage in the
Sublease Premises and from any failure to comply with this Sublease and the
Master Lease to the same extent as WJIA has agreed to indemnify Intelsat under
the terms of the Master Lease.

        14.  Confidentiality.  MIL 3 shall keep and maintain the confidentiality
             ---------------
of this Sublease and all information contained in the Master Lease, and shall
use it only for such purposes and in the manner previously agreed to in writing
by WJLA. Specifically, this Sublease and the Master Lease along with all terms
thereof and hereof shall be considered proprietary information of WJLA and
Intelsat, and shall not be given or disclosed to any person, firm or entity
(other than employees of MIL 3 on a "need to know" basis), and in no event shall
such proprietary information be given or disclosed to any real estate broker or
any other tenant or prospective tenant in the Building.

        15.  Event of Default; Remedies.
             --------------------------

        15.1.  Event of Default.  An "Event of Default" shall occur: (A) upon
               ----------------
the occurrence of an event of default described in the Master Lease, (each
reference to Landlord and Tenant to be deemed to refer to WJIA and MIL 3); (B)
in the event any representation or warranty which either party has made or makes
in this Sublease proves to be false or erroneous in any material way; or (C) in
the event that either party breaches or fails to observe or fails to perform any
term or covenant provided for in this Sublease and such breach or failure has
not been cured within ten (10) days after receiving written notice from the
other party of such breach or failure.

        15.2.  Remedies.  Upon the occurrence of an Event of Default, in
               --------
addition to any other rights and remedies either party may have under the
Sublease or at law or in equity, the other party shall have the rights and
remedies as set forth in this Sublease and the Master Lease.

        16.  Miscellaneous.
             -------------

        16.1.  Waivers.  The failure at any time of either party to require
               -------
performance of any obligation provided for in this Sublease shall in no way
affect the right to require such performance at any time thereafter, nor shall
the waiver of any breach constitute a waiver of any succeeding breach of the
same or any other such provision or constitute a waiver of the responsibility of
obligation itself.

        16.2.  Assignment: Subleasing.  MIL 3 shall not sublease, assign,
               ----------------------
mortgage, transfer or otherwise encumber this Sublease without the prior written
consent(s) of Intelsat, if

                                      -4-
<PAGE>

necessary, and WJLA, which consent, in the case of WJLA, shall not be
unreasonably withheld, conditioned or delayed. This Sublease shall be binding
upon and inure to the benefit of the parties named herein and the respective
successors and permitted assigns; provided, however, that any assignment of this
Sublease by WJLA or MIL 3 shall require the prior written consent of the other
except with respect to assignments to any entity controlling, controlled by or
under common control with the assigning party.

        16.3.  Notices.  All notices, requests, demands, communications or
               -------
information which are required to be or may be given under or in connection with
this Sublease shall be in writing and shall be deemed given when delivered
personally or by facsimile copy (with transmission confirmed), or upon receipt
(or in the date rejected or returned if not accepted) after dispatch by
certified or registered first class mail, postage prepaid, return receipt
requested, or a well-recognized overnight courier, directed to the party to whom
the same is so given or made at the address or facsimile number of such party as
hereinafter set forth or such other address or facsimile number as the parties
may hereinafter designate:

If to WJLA:               3007 Tilden Street, NW
                          Washington, D.C. 20006
                          Attn: General Manager
                          Fax: 202-364-1943

With copies to:           Allbritton Communications Company
                          808 17th Street, NW
                          Suite 300
                          Washington, D.C. 20008
                          Attn: General Counsel
                          Fax: 202-331-1898

If to MIL 3:              MIL 3, Inc.
                          3400 International Drive NW
                          Washington, D.C. 20008
                          Attn: Marc Cohen
                          Fax: 202-364-8554

        16.4.  Headings.  The headings of the sections of this Sublease are
               --------
inserted for convenience of reference only and shall not be deemed to constitute
a part hereof.

        16.5.  Entire Agreement; Amendments; Precedence.  This Sublease and
               ----------------------------------------
appended Exhibits contain the entire agreement between the parties hereto, and
supersede all previous agreements, negotiations and discussions between the
parties hereto. Any agreement made hereafter shall not operate to modify,
change, terminate or discharge this Sublease in whole or in part unless such an
agreement is in writing and is signed by both WJLA and MIL 3 and Intelsat, if
required.

        16.6.  Severability.  If any part of, or any provision of this Sublease
               ------------
or any other agreement, document or writing given pursuant to or in connection
with this Sublease shall be deemed to be invalid or unenforceable in any
respect, such part shall be ineffective to the extent

                                      -5-
<PAGE>

of such invalidity only and stricken as though never written, without in any way
affecting the remaining parts of such provisions or the remaining provisions of
this Sublease, provided that the removal of the unenforceable provision(s) does
not materially alter the benefits of the Sublease for either party.

        16.7.  Expenses; Brokers and Agents.  WJLA and MIL 3 shall each bear its
               ----------------------------
own expenses and costs, including, but not limited to, attorneys' fees and
expenses. Both parties represent and warrant to each other that no brokers have
been used regarding this Sublease. WHA shall indemnify and hold MIL 3 harmless,
and MIL 3 shall indemnify and hold WJLA harmless, from and against any claim or
claims of brokerage or other commission arising from or out of any breach of the
foregoing representation and warranty by the respective indemnitors.

        16.8.  Counterparts.  This Sublease may be executed in two counterparts,
               ------------
each of which, when executed, shall be deemed an original and all of which
together shall be deemed one and the same instrument.

        16.9.  Governing Law.  This Sublease, its validity and all rights,
               -------------
obligations, liabilities and responsibilities of the parties hereto, shall be
governed and interpreted in accordance with the laws of the District of Columbia
without giving effect to the principles of conflict of laws thereof.

                                      -6-
<PAGE>

     IN WITNESS WHEREOF, the undersigned have executed this Sublease as of the
date first noted above.

                                             WJLA-TV, a Division of Allbritton
                                             Communications Company:

Witness/Attest

  [sig]                                      By:   /s/ Terrence J. Connelly
--------------------------------------           ------------------------------
                                             Terrence J. Connelly
                                             President and General Manager

                                             MIL 3, Inc.

Witness/Attest

  /s/ Carrie L. Bell                         By:    /s/ Marc A. Cohen
--------------------------------------           ------------------------------
                                             Marc A. Cohen
                                             CEO

                                      -7-
<PAGE>

In the City of Washington  )(S)
District of Columbia       )(S)

I, Barbara A. Wylie, Notary Public in and for the District of Columbia, do
hereby certify that Terrence J. Connelly, who is named as the President of WJLA
in the foregoing and attached Sublease bearing the date of November 1, 1997,
personally appeared before me in said District of Columbia, the said Terrence J.
Connelly being personally known to me as the person named in said Sublease, and
acknowledged the Sublease to be the act and deed of WJLA-TV, a division of
Allbritton Communications Company and that he delivered the same as such for the
purposes stated therein.

     Given my hand and seal this 7 day of January, 1998.

                                    /s/ Barbara A. Wylie
                                  ----------------------
                                  Notary Public

My Commission Expires:

Barbara A. Wylie
Notary Public
District of Columbia
Commission Expires:  August 31, 1998

                                      -8-
<PAGE>

In the City of Washington  )(S)
District of Columbia       )(S)

I, Alma L. Fagan, Notary Public in and for the District of Columbia, do hereby
certify that Marc A. Cohen, who is named as the CEO of MIL 3 in the foregoing
and attached Sublease bearing the date of November 1, 1997, personally appeared
before me in said District of Columbia, being personally known to me as the
person named in said Sublease, and acknowledged the Sublease to be the act and
deed of MIL 3, Inc., a division of Allbritton Communications Company and that he
delivered the same as such for the purposes stated therein.

     Given my hand and seal this 7th day of January, 1998.

                                    /s/ Alma L. Fagan
                                  -------------------
                                  Notary Public

My Commission Expires:    7/31/02
                         ------------

                                      -9-
<PAGE>

                            OFFICE LEASE AGREEMENT
                            ----------------------

     THIS LEASE, dated as of the date specified in the Basic Lease Information,
is made between Landlord and Tenant.

                                   ARTICLE 1

                                   PREMISES

        Section 1.01.  Landlord leases to Tenant, and Tenant leases from
        -------------
Landlord, for the Term (as defined below) and subject to the provisions hereof,
to each of which Landlord and Tenant mutually agree, the Premises, together with
the right to use, in common with others, subject to such reason-able security
regulations as may be imposed by Landlord from time to time, the lobbies,
entrances, stairs, elevators, off-street loading areas (for loading and
unloading of materials and supplies) and other public portions of the Building,
which Building has been and is being constructed on the real property described
in Exhibit B hereto (the "Land"). For purposes of this lease, the term
"Building" means the office towers in which the Premises will be located, as
well as the concourses, lobbies, plazas, walkways, open spaces, landscaped
areas, and similar public areas located on, above, beneath, or immediately
adjacent to the Land, and any truck accessways, loading docks, or similar
facilities, if any, which serve the office towers. While such facilities are not
a portion of the Premises hereunder, Landlord agrees that Tenant shall be
permitted a single Pod connection for access to and the right to use, and to
have officers, employees, contractors and invitees of Tenant use, the loading
dock facilities and the cafeteria all located within the INTELSAT Headquarters
Building during the Term of this lease and any extension hereof, at no
additional charge to Tenant or its officers, employees or invitees other than
payment at prevailing charges imposed on other users for food, beverages and
services provided at the cafeteria plus any additional sales tax which may be
applicable, it being understood and agreed that there will only be one
connection at a single location between the Building and the remainder of the
INTELSAT Headquarters Building.

                (a)  The Rentable Area of the Premises is approximately as
stated in the Basic Lease Information and shall be specifically calculated by
Landlord's architect when floor plans are complete, in accordance with Exhibit E
attached hereto. Upon such determination by Landlord's architect, the Rentable
Area of the Premises and the Annual Rental as those terms are defined in this
lease, shall be appropriately adjusted to reflect the number of square feet of
Rentable Area of the Premises as determined by such calculation. In the event of
any future increase or decrease in the size of the Premises (by reason of the
exercise by Tenant of its expansion option pursuant to Article 33 or otherwise),
Tenant's Proportionate Share shall be appropriately adjusted. Promptly after
Landlord's architect has calculated the Rentable Area of the Premises, Landlord
will give Tenant written notice of the Rentable Area of the Premises thus
calculated. In the event that Tenant disagrees with such calculation based on a
calculation performed by its architect and gives written notice to Landlord of
such disagreement within thirty (30) days after receipt of such notice
containing the calculation provided by Landlord's architect, the Rentable Area
of the Premises shall be determined in the following manner. If the Rentable
Area of the Premises as calculated by Landlord's architect is within one hundred
(100) square feet of the Rentable Area of the Premises as calculated by Tenant's
architect, then the Rentable Area of the Premises for purposes hereof shall
equal the average of the two
<PAGE>

calculations. In the event the two calculations are not within one hundred (100)
square feet, Landlord's architect and Tenant's architect shall mutually agree
upon a third licensed, qualified and independent architect. In the event
Landlord's architect and Tenant's architect are not able to agree on a third
architect within fifteen (15) days after Landlord and Tenant are notified of the
determination of the architects, either party may request that the President of
the Washington Board of Realtors appoint the third architect. The third
architect shall calculate the Rentable Area of the Premises in accordance with
Exhibit E, and such calculation will be final and binding upon both Tenant and
Landlord. Landlord and Tenant shall each bear the cost of their respective
architects, and the cost of the third architect shall be borne equally between
Landlord and Tenant.

                (b)  The Rentable Area of the Building shall be calculated by
Landlord's architect when the Base Building Work (as defined in Exhibit C) is
complete, in accordance with Exhibit E attached hereto, with the Rentable Area
of each floor of the Building to be calculated for purposes hereof as if such
floor were a single tenancy floor. Landlord will give Tenant written notice of
the Rentable Area of the Building thus calculated by its architect. In the event
that Tenant disagrees with such calculation based on a calculation performed by
its architect and gives written notice to Landlord of such disagreement within
thirty (30) days after receipt of such notice containing the calculation
provided by Landlord's architect, the Rentable Area of the Building shall be
determined in the following manner. If the Rentable Area of the Building as
calculated by Landlord's architect is within two hundred (200) square feet of
the Rentable Area of the Building as calculated by Tenant's architect, then the
Rentable Area of the Building for purposes hereof shall equal the average of the
two calculations. In the event the two calculations are not within two hundred
(200) square feet, Landlord's architect and Tenant's architect shall mutually
agree upon a third licensed, qualified and independent architect. In the event
Landlord's architect and Tenant's architect are not able to agree on a third
architect within fifteen (15) days after Landlord and Tenant are notified of the
determination of the architects, either party may request that the President of
the Washington Board of Realtors appoint the third architect. The third
architect shall calculate the Rentable Area of the Building in accordance with
Exhibit E, and such calculation will be final and binding upon both Tenant and
Landlord. Landlord and Tenant shall each bear the cost of their respective
architects, and the cost of the third architect shall be borne equally between
Landlord and Tenant.

                (c)  Tenant's Proportionate Share shall be the percentage
equivalent of a fraction having as its numerator the Rentable Area of the
Premises determined under Section 1.02(a) and having as its denominator the
Rentable Area of the Building determined under Section 1.02(b). In the event of
any future increase or decrease in the size of the Premises (by reason of the
exercise by Tenant of its expansion option pursuant to Article 33 or otherwise),
Tenant's Proportionate Share shall be appropriately adjusted.

                (d)  The Rentable Area of the Premises and Rentable Area of the
Building determined pursuant to this Section 1.02 shall be used as the basis for
the computation of all items of Rental and the computation of Tenant's
Proportionate Share. At the request of either party, the parties shall, from
time to time, execute instruments confirming the Rentable Area of the Premises,
the Rentable Area of the Building, and the Tenant's Proportionate Share.

                                      -2-
<PAGE>

                                   ARTICLE 2

                                     TERM

        Section 2.01.  (a) The term of this lease (the "Term") shall begin on a
        -------------
date (the "Commencement Date") which is the earlier of: (i) the date of Tenant's
occupancy of the Premises for the conduct of its normal business operations,
(ii) seven and one-half (7 1/2) months after the date on which construction of
the Base Building Work (as defined in Exhibit C) is substantially completed or
(iii) fifteen (15) days after (a) Tenant Build-out as described in Exhibit C has
been substantially completed and (b) the Communication Systems described in
Exhibit K have been installed on the Building and Land, so as to permit Tenant
to occupy the Premises and conduct its normal business operations therein, it
being stipulated that Tenant agrees, subject to delay by force majeure as
defined in Section 2.01(b), to exercise reasonable diligence to complete and
install such Tenant Build-out and Communication Systems after Tenant is afforded
access to the Land, Building and Premises for such purpose. Unless sooner
terminated, the Term shall end at midnight on the Expiration Date. Landlord
shall deliver to Tenant at least fifteen (15) days' prior written notice of the
date of substantial completion of the Base Building Work.

                (b)  As used herein, the term "force majeure" means a lockout,
strike or other labor or industrial circumstance (whether on the part of
employees of Landlord or Tenant), civil disturbance, future order of any
government, court or regulatory body claiming jurisdiction, act of the public
enemy, riot, sabotage, blockage, embargo, failure or inability to obtain, or
delay in obtaining materials, supplies or labor through ordinary sources by
reason of short-ages or priority or regulation or order of any government or
regulatory authority or other cause beyond the reasonable control of Landlord or
Tenant, lightning, earthquake, fire, storm, hurricane, flood, washout,
explosion, Act of God, failure or refusal by the Landlord or Tenant, as the case
may be, to perform or observe its agreements or undertakings hereunder, or any
cause whatsoever beyond the reasonable control of Landlord or Tenant, as the
case may be, or its contractors, or other representatives, whether or not
similar to any of the causes hereinabove enumerated; provided, however, that for
purposes of this definition lack of funds by Landlord or Tenant shall not be
deemed to be a cause beyond the control of Landlord or Tenant, as the case may
be, and a force majeure circumstance shall be deemed to exist only so long as
Landlord or Tenant promptly notifies the other in writing thereof specifying the
particulars and is exercising due diligence to remove or overcome such force
majeure circumstance (except that nothing contained in this definition of force
majeure or elsewhere in this lease shall require or obligate Landlord or Tenant
to settle a strike or other labor dispute when it does not wish to do so).

        Section 2.02.    Provided Tenant performs all of Tenant's obligations
        -------------
under this lease, including the payment of Rental (as defined below), Tenant
shall, during the Term, enjoy the Premises without disturbance from Landlord or
any other persons claiming or acting by, through, or under Landlord; subject,
however, to the terms of this lease. This covenant and all other covenants of
Landlord now or hereafter in this lease shall be binding upon Landlord and its
successors only with respect to breaches based on Landlord's acts or omissions
occurring during its and their respective ownership of Landlord's interest
hereunder (including Landlord's right, title and interest in and to the Ground
Lease described in Section 25.01 and any buildings and improvements on the land
described therein).

                                      -3-
<PAGE>

        Section 2.03.    Landlord shall notify Tenant of the date determined to
        -------------
be the Commencement Date pursuant to Section 2.01 and, within fifteen (15) days
after delivery of such notice, Landlord and Tenant shall execute a written
instrument substantially in the form of Exhibit D attached hereto confirming
such date as the Commencement Date; provided that if Tenant in good faith
disagrees with Landlord as to the Commencement Date thus determined by Landlord,
such instrument specifying the actual Commencement Date shall not be executed
until resolution of such dispute by agreement of Tenant and Landlord or by final
judgment of a court of competent jurisdiction not subject to further appeal. Any
failure of the parties to execute such written instrument shall not affect the
validity of the Commencement Date as determined as aforesaid.

                                   ARTICLE 3

                      DELIVERY OF THE PREMISES TO TENANT

        Section 3.01.    Landlord will endeavor to substantially complete the
        -------------
floor(s) in which the Premises are located and to construct and install in the
Premises the Base Building Work (as defined in Exhibit C hereof) seven and one-
half (7-1/2) months prior to the Target Commencement Date specified in the Basic
Lease Information. If for any reason Landlord cannot deliver the Premises to
Tenant by such date, this lease shall not be void or voidable, nor shall
Landlord be liable for any loss or damage resulting therefrom. Notwithstanding
the foregoing, in the event Landlord has not substantially completed the Base
Building Work by April 1, 1989, which date shall be extended by the number of
days of Tenant delay as described in Article 6 and 7 of Exhibit C, Landlord
shall be liable to Tenant for the amount by which (i) Tenant's rent expenses in
its present space, or substitute space, as the case may be, exceed (ii) the
Rental Tenant would reasonably be obligated to pay Landlord hereunder had Tenant
been occupying the Premises (without regard to any free rent period), which
excess shall be computed for the period commencing on April 1, 1989 (as extended
aforesaid by Tenant delays) and ending on the earlier of April 1, 1990 or the
date on which Landlord, at Landlord's option sends written notice to Tenant
giving Tenant the right to terminate this lease by reason of the non-completion
of the Base Building Work. In the event Landlord has not substantially completed
the Base Building Work by April 1, 1990, which date shall be extended by the
number of days of Tenant delays as described in Article 6 and 7 of Exhibit C,
or, in the event Landlord has given Tenant the right, exercisable at any time
prior to the date on which the Base Building Work is substantially completed, to
terminate the lease pursuant to the preceding sentence, Tenant shall have the
right to terminate this lease by giving Landlord written notice of such
election, in which event neither Landlord nor Tenant shall have any further
liability or responsibility hereunder or in connection herewith; provided that
Tenant may promptly remove any property of Tenant which Tenant had placed or
installed in or on the Premises, Building or Land (and repair any damage caused
by such removal) and shall be entitled to receive a refund from Landlord of the
monthly installment of Annual Rental paid by Tenant incident to the execution of
this lease. Tenant may not, without Landlord's consent, enter or occupy the
Premises, Building or Land until the Base Building Work is substantially
completed. However, Landlord agrees that it will permit Tenant and its
contractors to have access to the Premises, Building or Land, or portions
thereof as applicable as promptly as practicable to commence construction and
installation of Tenant Build-out and Communication Systems prior tot the
substantial completion of the Base Building Work if and to the extent Landlord
determines in good faith that such work by Tenant

                                      -4-
<PAGE>

or its contractors will not unreasonably interfere with the work of Landlord and
its contractors in completing the Building and Base Building Work.

        Section 3.02.    The scheduling and coordination of Tenant's contractors
        -------------
and their workers and mechanics will be subject to reasonable regulation by
Landlord or Landlord's contractor to avoid interferences with labor employed by
Landlord, Landlord's contractor or their mechanics or subcontractors and their
workers or mechanics. The foregoing license to enter prior to the Commencement
Date, however, is conditioned upon Tenant's workers and mechanics working in
harmony and not unreasonably interfering with the labor employed by Landlord,
Landlord's mechanics or contractors or by any other tenant or its contractors.
Any such entry before the Commencement Date shall be subject to all terms of
this lease, except the covenant to pay Rental. Landlord shall not be responsible
for any loss or damage to the Tenant Build-out.

        Section 3.03.    The terms of Exhibit C hereto shall govern the
        -------------
construction and-installation of Tenant Build-out.

                                   ARTICLE 4

                          ACCEPTANCE OF THE PREMISES
                            AND BUILDING BY TENANT

     Taking possession of the Premises by Tenant and commencement of its normal
business operations therein shall be conclusive evidence that Tenant: (a)
accepts the Premises as suitable for the purposes for which they are leased (b)
accepts the Building and every part and appurtenance thereof) as being in a good
and satisfactory condition; and (c) waives any defects in the Premises or the
Building except for the completion of those items, if any, on Landlord's punch
list, and latent defects, and except for the completion or correction of those
items, if any, which shall be specified by written notice given by Tenant to
Landlord within thirty (30) days after Tenant has taken possession of the
Premises and commenced its normal business operations therein.  Landlord shall
not be liable, except for gross negligence or willful misconduct, to Tenant or
any of its agents, employees, licensees, servants, or invitees for any injury or
damage to person or property due to the condition or design of or any defect in
the Building or its mechanical systems and equipment which may exist or occur,
and Tenant, for itself and its agents, employees, licensees, servants, and
invitees, expressly assumes all risks of injury or damage to person or property,
either proximate or remote, resulting from the condition of the Premises or the
Building.

                                   ARTICLE 5

                                    RENTAL

        Section 5.01.    Subject to the last sentence of this Section 5.01,
        -------------
commencing on the Commencement Date, Tenant shall Day to Landlord monthly, in
advance, without demand, on the first day of each calendar month during each
Lease Year, an annual rental ("Annual Rental") in an amount equal to 1/12 of the
Annual Rental specified in the Basic Lease Information, subject to adjustment as
provided in Section 1.02, and Article 32 hereof. [redacted text] shall be

                                      -5-
<PAGE>

payable in advance by Tenant on the date of execution of this lease.  If the
Commencement Date is a date other than the first day of a calendar month, then
the monthly installment of Rental for the first month for which rent is owing,
being a fractional month, shall be appropriately prorated.  If the Expiration
Date is a date other than the last day of a calendar month, then the monthly
installment of Rental for the last month for which rent is owing, being a
fractional month, shall be appropriately prorated.  Landlord hereby waives and
abates payment of the Annual Rental for the first seven (7) months of the Term.

        Section 5.02.    All Rental shall be paid to Landlord by Tenant when
        -------------
due, without deduction, offset or counter-claims, in lawful money of the United
States, at Landlord's Address for Notices as specified in the Basic Lease
Information, or such other place as Landlord may from time to time designate.
The term "Rental" as used herein means the then applicable Annual Rental,
Tenant's Proportionate Share of Basic Costs Excess (as hereinafter defined), and
all other sums payable by Tenant under this lease. All past due installments of
Rental shall bear interest from the date due until paid at a rate per annum
equal to [redacted text] above the prime or base rate (the "Prime Rate")
publicly announced by The Riggs National Bank of Washington, D.C. (or its
successor), from time to time; provided, however, that any interest payable
pursuant to this Section 5.03 shall never exceed the Highest Lawful Rate. The
term "Highest Lawful Rate" as used herein shall mean the maximum rate of
interest from time to time permitted to be charged under applicable law to
Tenant with respect to the indebtedness for which such interest is charged under
this lease.

        Section 5.03.    It is agreed by Landlord and Tenant that no Rental for
        -------------
the use, occupancy or utilization of the Premises shall be, or is, based in
whole or in part on the net income of profits derived by any person from the
Building or the Premises, and the Tenant further agrees that it will not enter
into any sublease, license, concession or other agreement for any use, occupancy
or utilization of the Premises which provides for a rental or other payment for
such use, occupancy or utilization based in whole or in part on the net income
or profits derived by any person from the Premises so leased, used, occupied or
utilized. Nothing in the foregoing sentence, however, shall be construed as
permitting or constituting Landlord's approval of any sublease, license,
concession, or other use, occupancy, or utilization agreement not otherwise
approved by Landlord in accordance with the provisions of Article 18 hereof.

                                   ARTICLE 6

                                OPERATING COSTS

        Section 6.01.    Throughout the Term, beginning with the Fiscal Year
        -------------
following the Fiscal Year in which the Commencement Date occurs, Tenant shall
pay Tenant's Proportionate Share of the amount ("Basic Costs Excess") by which
Basic Costs for such Fiscal Year exceed the Basic Costs Base Amount. Such
payments of Tenant's Proportionate Share of Basic Costs Excess shall be made as
follows:

                (a)  Before the beginning of each Fiscal Year during the Term,
commencing with the first Fiscal Year after the Fiscal Year in which the
Commencement Date occurs, Land-lord shall furnish Tenant with Landlord's
estimate of the Basic Costs Excess for such Fiscal Year. Subject to subparagraph
(b)(v) of this Section 6.01, by the first day of each month during

                                      -6-
<PAGE>

such Fiscal Year, Tenant shall pay 1/12th of its Proportionate Share of the
estimated Basic Costs Excess for such Fiscal Year.

                (b)  (i)  Within the first one hundred twenty (120) days of each
Fiscal Year during the Term (beginning with the second Fiscal Year following
calendar year 1988), and within one hundred twenty (120) days after the end of
the Fiscal Year during which the Expiration Date occurs, or as soon thereafter
as reasonably practical, Landlord shall furnish to Tenant a statement ("Expense
Statement") of the actual Basic Costs for the previous Fiscal Year, certified to
be true and accurate by Landlord to its knowledge and belief.

                     (ii) Within thirty (30) days after the delivery of the
Expense Statement, a lump sum payment will be made by Tenant equal to the
amount, if any, by which Tenant's Proportionate Share of the actual Basic Costs
exceeds the amount, if any, which Tenant has paid toward the estimated Basic
Cost Excess for such previous Fiscal Year.

                     (iii)  If Tenant's Proportionate Share of the actual Basic
Costs is less than the amount Tenant has paid toward the estimated Basic Costs
Excess for such previous Fiscal Year, Landlord shall refund the excess to Tenant
within thirty (30) days after the issuance of the Expense Statement or, at
Landlord's option, Landlord shall apply such amount to the next payments of
Rental due hereunder.

                     (iv) The effect of the reconciliation payment or adjustment
pursuant to (ii) or (iii) above is that Tenant shall pay during each Fiscal Year
during the Term its Proportionate Share of the Basic Costs Excess.

                     (v)  Notwithstanding anything herein contained to the
contrary, Landlord hereby waives and abates payment by Tenant of Tenant's
Proportionate Share of Basic Costs Excess for the period ending at the
expiration of twelve (12) full calendar months after the Commencement Date.

                     (vi) In the event that Tenant pays to Landlord Landlord's
determination of the amount due pursuant to subparagraph (b)(ii) of this Section
6.01, and included with such payment is a notice advising Landlord that Tenant
disputes the amount Landlord claims is owing together with the reasons for such
dispute in reasonable detail, then in the event that it is ultimately determined
that Tenant's payment exceeded the amount which should have been due, Tenant
shall be entitled to interest at the Prime Rate plus one percent (1%) per annum
on the amount of the overpayment from the date paid until the Landlord remits to
Tenant the amount of the overpayment.

                (c)  Within thirty (30) days after delivery of an Expense
Statement, Tenant shall have the right to notify Landlord if it intends to
examine Landlord's books and records with respect to such Expense Statement. If
Tenant so notifies Landlord, then Tenant and its representatives shall have the
right, at Tenant's expense, during normal business hours for a period of ninety
(90) days after Tenant's notice, to examine Landlord's books and records
relating to Basic Costs for the Building for the previous Fiscal Year. Tenant
shall notify Landlord within such ninety- (90) day period if it disputes such
Expense Statement setting forth the reasons therefor (a "Notice of Dispute"). If
Tenant either (i) fails to notify Landlord of its

                                      -7-
<PAGE>

intention to examine Landlord's books and records within thirty (30) days after
delivery of an Expense Statement, or (ii) fails to give Landlord a Notice of
Dispute within the ninety- (90) day period of examination hereinabove referred
to, then Tenant shall be deemed to have accepted such Expense Statement for all
purposes hereunder. If Landlord shall have overstated Tenant's obligation for
Basic Costs for any calendar year, Landlord shall promptly refund such excess.

                (d)  If the Term ends on a date other than the last day of a
Fiscal Year, then the actual Basic Costs incurred during the Fiscal Year in
which the Expiration Date occurs (as the same may be adjusted pursuant to the
last paragraph of Section 6.02) shall be computed and an appropriate proration
shall be made so that Tenant pays that portion of its Proportionate Share of
Basic Costs Excess incurred during such Fiscal Year determined by reference to a
fraction, the numerator of which is the number of days during such Fiscal Year
that are included in the Term, and the denominator of which is the number of
days in such Fiscal Year.

        Section 6.02.  As used herein, "Basic Costs" means all expenses, costs,
        -------------
and disbursements described hereinafter (net of discounts, credits, rebates or
direct reimbursements, including, without limitation, reimbursement from tenants
or other third-parties or from any insurance company or under-writer) which
Landlord incurs in connection with the operation, repair, and maintenance of the
Building (including all facilities installed in subsequent years if such
facilities are commonly installed in similar first-class office buildings in
Washington, D.C.) computed on an accrual basis. All Basic Costs shall be
determined according to generally accepted accounting principles. Basic Costs
shall include the following:

                (a)  Wages, salaries, and fees of all personnel or entities
(exclusive of Landlord's executive personnel) engaged in the operation, repair,
maintenance, or security of the Building, including taxes, insurance, and
benefits relating thereto and on-site rental paid by the Building manager;
provided, however, that if during the Term such personnel or entities are
working on projects being periodically developed or operated by Landlord as well
as the Building, their wages, salaries, fees, and related expenses shall be
appropriately allocated among all of such projects (based on time records to be
maintained by all personnel engaged in such projects or on some other reasonable
method of allocation) and only that portion of such expenses reasonably
allocable to the Building shall be included as a "Basic Cost"

                (b)  All supplies and materials used in the operation, repair,
security, and maintenance of the Building.

                (c)  Costs of all maintenance, janitorial, security and service
agreements for the Building and the equipment therein, including, without
limitation, alarm service, water treatment services, janitorial services, window
leaning, service on electrical and mechanical components, rubbish removal,
elevator maintenance, extermination service, plumbing service, and interior and
exterior landscaping.

                (d)  Cost of all insurance relating to the Building for which
Landlord is responsible hereunder, or which Landlord considers reasonably
necessary for the operation of the Building, including, the cost of property,
casualty and liability insurance applicable to the Building and Landlord's
personal property used in connection with the maintenance, repair and operation
of the Building (not including any personal property used by Landlord in
connection

                                      -8-
<PAGE>

with its occupancy of any of the Building). If during any Fiscal Year (or
partial Fiscal Year) during the Term (including the Fiscal Year in which the
Commencement Date occurs), Landlord elects to self-insure with respect to
property insurance in accordance with Section 15.06, Basic Costs shall include
the cost which Landlord would otherwise have incurred at competitive prevailing
rates to obtain such property insurance for the Building; provided, however,
that when and if Landlord first elects to self-insure with respect to property
insurance on or after the Commencement Date, the deemed cost (determined on a
daily basis) of such self-insurance included in Basic Costs during the first
twelve (12) months next ensuing (or during such lesser period while Landlord
continues to self-insure with respect to property insurance) shall not
thereafter increase and shall at all times thereafter while Landlord elects to
self-insure with respect to property insurance be conclusively deemed to be the
cost (determined on a daily basis) of Landlord's self-insurance with respect to
property insurance for purposes of computing Basic Costs during any period under
this lease, except that in the event Landlord elects on one or more additional
times to self-insure with respect to property insurance after having had such
insurance provided by a third-party insurance company for a continuous period in
excess of five (5) years, then the maximum dollar amount of property insurance
which can be included in Basic Costs during such self-insurance period shall be
the cost of the third-Party insurance incurred by Landlord during the full
Fiscal Year immediately preceding the year in which Landlord so elected to self-
insure.

                (e)  All utility costs of common areas of the Building (that is
areas not devoted to office or retail space) including, without limitation,
costs of water, power, fuel, heating, lighting, air conditioning, and
ventilating and fees of engineers or electrical consulting firms engaged to do
work relating to such utility costs or the determination thereof, it being
understood and agreed that the electricity consumed to provide heating,
ventilating and air-conditioning to the common areas in central pumps and
facilities for providing heated and chilled to the entire Building shall be
determined by metering the electrical consumption of such central pumps and
facilities and by allocating the cost of such electricity in proportion to the
relative number of Btu's taken from (for heating) or added to (for air-
conditioning) the stream of heated and chilled water delivered to the air-
handling units serving the common areas as compared to the number of Btu's taken
from or added to (as applicable) the stream of heated and chilled water
delivered to the air-handling units serving all portions of the Building other
than the common areas, with Landlord to provide and maintain all meters
necessary to perform such allocation.

                (f)  Cost of repairs and maintenance of the Building.

                (g)  Amortization of the cost of installation of capital
improvement items (i) which are primarily to reduce operating costs for the
general benefit of the Building's tenants but not in excess of the reasonably
anticipated amount of yearly savings of operating costs resulting from such
capital improvements as determined by Landlord in good faith, (ii) which are
reasonably necessary for the continued operation of the Building as first-class
office building, or (iii) which are necessary to comply with a statute, rule,
regulation or directive promulgated by any governmental authority after the
Commencement Date, together with interest on the unamortized cost at the rate of
the Prime Rate. All such costs shall be amortized over the reasonable life of
the capital investment items, with the reasonable life and amortization schedule
being determined in accordance with generally accepted accounting principles.

                                      -9-
<PAGE>

                (h)  Landlord's reasonable direct costs for the preparation of
Expense Statements for both outside accountants and accountants employed by
Landlord.

                (i)  A management fee or allowance, whether or not actually paid
by Landlord to a contract manager of the Building during a Fiscal Year, equal to
three percent (3%) of the Rental per square foot of Rentable Area payable under
this lease multiplied by the greater of (x) 90% of the Rentable Area of the
Building, or (y) the weighted daily average number of square feet of Rentable
Area of the Building occupied by tenants (including Landlord to the extent
Landlord occupies space in the Building) during the Fiscal Year. In the event
the Building is managed by a contract manager, Basic Costs shall not include
both the fee actually paid to such contract manager and an additional three
percent (3%) of the amounts specified above. Further, in any event, there shall
be excluded from Basic Costs under Section 6.02(a) the wages, salaries and fees
(and taxes, insurance and benefits and benefits related thereto) for the time of
personnel or entities devoted to performing management services or functions.

                (j)  Legal and appraisal fees relating to the operation, repair
or maintenance of the Building, including legal fees incurred in order to reduce
Basic Costs, including without limitation the costs (including expert witness
fees) incurred by Landlord in the filing, institution and prosecution of any
application or proceeding filed or instituted by Landlord in order to reduce the
taxes included in Basic Costs.

                (k)  The reasonable maintenance and repair costs which Landlord
would have incurred (and which would otherwise be included in Basic Costs) in
the absence of manufacturers and vendors warranties.

                (l)  One sixth (1/6th) of the costs of those items or services
which benefit generally the occupants of the INTELSAT Headquarters Building
consisting of landscaping and ground maintenance costs, the costs of snow
removal, costs of periodically washing both the exterior and interior of the
INTELSAT Headquarters Building, and the cost of diesel fuel for the emergency
generator.

          If during all or part of any Fiscal Year (or partial Fiscal Year) of
the Term, Landlord shall not furnish any particular item of work or service
(which would constitute an item of Basic Costs hereunder) to 100% of the Rent-
able Area of the Building (and Landlord's total cost of supplying such items of
work or service to the Building is less than it otherwise would have been had
Landlord supplied such item to 100% of the Rentable Area of the Building),
because (i) less than all of the Building is occupied or (ii) such item of work
or service is not desired or required by any tenant, or (iii) any tenant is it
self obtaining and providing such item of work or service, then an adjustment
shall be made in computing the Basic Costs for such Fiscal Year (or partial
Fiscal Year) so that the Basic Costs shall be increased for such Fiscal Year (or
partial Fiscal Year) to the amount that would have been reasonably incurred had
Landlord provided such item of work or service to 100% of the Rentable Area of
the Building for the entire Fiscal Year (or partial Fiscal Year).

        Section 6.03.  Notwithstanding anything in Section 6.02 to the contrary,
        -------------
Basic Costs shall not include:

                                     -10-
<PAGE>

                (a)  any tenant work performed or alteration of space leased to
Tenant or other tenants or occupants of the Building, whether such work or
alteration is performed for the initial occupancy by such tenant or occupant or
thereafter or any work or service performed or alteration or improvement of
space provided to or for any tenant or occupant of the Building for which a
separate or special charge would be made to Tenant under the terms of this lease
if such work or service were performed or alteration or improvement of space
were provided by Landlord to or for Tenant, or which work, service, alteration
or improvement is of a nature that Landlord is not required to provide or
perform same to or for Tenant under the terms of this lease without imposing an
additional charge therefor as additional Rental or in addition to the Rental
otherwise payable under the terms hereof;

                (b)  costs of negotiation, preparation, amendment, extension or
enforcement of leases or which are incurred in connection with any dispute
between Landlord and any tenant or as a consequence of any violation of or
breach of a lease by any tenant;

                (c)  interest and amortization of indebtedness or any costs of
financing or refinancing, depreciation or ground rent (other than any amount
payable by Landlord for insurance or repairs or other items of Basic Costs under
any ground lease, to the extent such amounts are otherwise includable in Basic
Costs under Section 6.02 and 6.03 hereunder);

                (d)  compensation paid to officers or executives of Landlord
(other than to the extent included in the management fee referred to in Section
6.02(i));

                (e)  leasing commissions and advertising and promotional
expenses and any other costs of leasing or attempting to lease space in the
Building;

                (f)  electricity consumption other than as specifically provided
in Section 6.02(e), and Utility Costs as defined in Section 8.01(b), and any
Real Estate Taxes defined in Section 9.02 (a).

                (g)  If any partnership, joint venture, corporation or other
entity controlled by Landlord or in which Landlord owns any interest (other than
a minority interest in stock of a publicly-held corporation) (a "Landlord's
Affiliate") shall provide any materials or perform any work or provide any
services the cost of which is included in "Basic Costs" hereunder, the amount of
the charges of such Landlord's Affiliate for such materials, work or services to
be included in "Basic Costs" shall be limited to reasonable charges not in
excess of the charges for similar materials, work or services which would be
charged by an independent entity engaged in the business of providing or
performing such materials, work or services under a competitive contract
negotiated in good faith at arm's length; and the charges of such Landlord's
Affiliate included in "Basic Costs" shall further be reduced by the amounts, if
any, of the charges for the time of personnel (if any) employed or used by such
Land-lord's Affiliate in providing such services or performing such work which
is otherwise charged directly as a part of "Basic Costs" of operating,
maintaining or repairing the Building under Section 6.02(a);

                (h)  Costs of structural repairs and costs of replacement,
repair, restoration or reconstruction of the Building or any part thereof or
facilities or improvements therein

                                     -11-
<PAGE>

necessitated by damage thereto or destruction thereof caused by fire, storm,
explosion or other casualty;

                (i)  Rental paid under any lease of elevators, air-conditioning
or heating equipment or machinery, emergency generators or other equipment or
machinery normally regarded as capital items unless such equipment (A) is used
for repair work or in an emergency situation and (B) is leased for a term of
three (3) months or less (but not including any lease which provides or is
accompanied by an option of Landlord to purchase the equipment or machinery
leased);

                (j)  Charges for any inventory of consumable supplies for use in
the Building prior to the time such supplies are actually taken out of inventory
for use in the Building;

                (k)  Compensation of clerks or other personnel working in any
commercial concession or business operated by Landlord or any Landlord's
Affiliate in the Building;

                (l)  Except as otherwise provided in Article 26, any costs or
expenses of operating, maintaining or repairing any parking spaces, parking
areas or parking facilities in or about the Building or Land.

        Section 6.04.  If the number of square feet of the Rentable Area of the
        -------------
Premises changes (by reason of the exercise by Tenant of its option pursuant to
Article 33 or otherwise), then Tenant's Proportionate Share shall be adjusted
effective as of the date of any such change in accordance with Section 1.02
hereof. Any charges made pursuant to this Section 6.04 shall not alter the
computation of Basic Costs as provided in Section 6.02 of this lease. If
Tenant's Proportionate Share is adjusted, the reconciliation payments for
Tenant's Proportionate Share of Basic Costs Excess pursuant to Section 6.01(b)
for the Fiscal Year in which such change occurs shall be computed based on the
daily weighted average of Tenant's Proportionate Share during such Fiscal Year.

                                   ARTICLE 7

                SERVICES BY LANDLORD AND LANDLORD'S OBLIGATIONS

        Section 7.01.    While Tenant is occupying the Premises and is not in
        -------------
default under this lease, Landlord shall furnish the Premises with: (a)
passenger elevator service in common with other tenants for access to and from
the Premises twenty-four (24) hours per day and seven (7) days per week;
provided, however, that Landlord may reasonably limit the number of elevators to
be operated during periods of construction or for safety or maintenance
purposes; and (b) the services provided for in Section 8.02. In addition, while
Tenant is occupying the Premises and is not in default under this lease,
Landlord shall make available to Tenant for Tenant's use, freight elevator
service at the loading dock of the INTELSAT Headquarters Building during normal
business hours, and shall make such service available to Tenant after normal
business hours upon reasonable prior notice. If Tenant requires services which
are not specified herein and Landlord provides such services to Tenant, Tenant
will pay to Landlord, upon demand, as additional Rental, the actual cost
incurred by Landlord to provide such services including a reasonable allocation
of Landlord's overhead, administrative and related costs.

                                     -12-
<PAGE>

        Section 7.02.    Landlord shall operate the Building as a first-class
        -------------
District of Columbia modern office building. Landlord, at its cost and expense,
shall keep and maintain the Building, its fixtures, appurtenances, systems and
facilities, and the sidewalks, plazas and landscaped areas adjoining the
Building, in good working order, condition and repair and shall make all
repairs, structural and otherwise, interior and exterior, ordinary or
extraordinary, as and when needed in or about the Premises or the Building,
except the leasehold improvements and those repairs for which Tenant is
expressly responsible pursuant to any other provisions of this lease. Landlord
shall, at its expense, finish, decorate and maintain the elevator lobbies and
all other common areas in the Building, and the floors, ceilings and surface of
all walls adjacent thereto, in a manner and of a quality consistent with a
first-class District of Columbia modern office building.

        Section 7.03.    Landlord, at its cost and expense, shall:
        -------------

                     (i)  keep the sidewalks, plazas and landscaped areas
adjoining the Building free of accumulation of snow and ice, dirt, refuse,
rubbish and unlawful obstructions;

                     (ii) keep the lobbies, common and public areas of the
Building clean and presentable;

                     (iii)  care for and maintain the shrubbery, planting and
landscaping, if any, on the plaza or plazas adjacent to the Building or other
public areas of the Building; and

                     (iv) provide Tenant, its employees and invitees prompt
access (in a manner consistent with a first-class modern office building in the
District of Columbia) into the Building (through the lobby) and the Premises
twenty-four (24) hours each day, seven (7) days per week, subject to such
reasonable security regulations as may be imposed by Landlord from time to time.

                     (v)  Provide and maintain a building directory on the
ground floor of the Building adjacent to the entrance and elevator lobby to
provide listing for Tenant and up to thirty six (36) listings for departments
and executives or employees of Tenant, of a quality and style consistent with
building directories customarily provided in first-class office buildings in
Washington, D.C.

        Section 7.04.  Nothing contained in this Article 7 or Section 8.02 [or
        -------------
any other provision of this lease] shall preclude Landlord from including in
Basic Costs (pursuant to Sections 6.02 and 6.03) any of the costs and expenses
referred to in this Article 7 or any other provision of this lease to the extent
the same are within the definition of Basic Costs.

                                   ARTICLE 8

                                   UTILITIES

        Section 8.01.    (a) Landlord shall, at Landlord's expense, install a
        -------------
meter or meters to determine the electricity directly furnished to the Premises,
and a meter or meters to determine the electricity furnished to a separate air
cooling chiller serving only the Premises. Tenant shall pay when due the cost
for such electricity directly to the supplying utility company. Landlord

                                     -13-
<PAGE>

shall also meter, at no cost to Tenant, all electricity directly furnished to
Pods L and M of the Building, and Tenant shall not be liable or responsible for
the cost of such electricity.

                (b)  As used herein, the term "Utility Costs" means that part of
the cost of electricity used in central pumps and facilities providing heated
and chilled water for heating and air-conditioning within the entire Building
which is allocated to the Premises on a Btu basis as provided hereinafter. In
this regard, it is agreed that the electrical consumption of such central pumps
and facilities shall be metered and that a share of the cost of such electricity
shall be allocated to the Premises in proportion to the relative number of Btu's
taken from (for heating) or added to (for air-conditioning) the stream of heated
and chilled water delivered to the air-handling units serving the Premises as
compared to the number of Btu's taken from or added to (as applicable) the
stream of heated and chilled water delivered to the air-handling units serving
all portions of the Building other than the Premises, with Landlord to provide
and maintain all meters necessary to perform such allocation. In this regard, it
is further agreed that:

                     (i)  Before the beginning of each Fiscal Year during the
Term, Landlord shall furnish Tenant with Landlord's estimate of the Utility
Costs for such Fiscal Year or partial Fiscal year. By the first day of each
month during such Fiscal Year, Tenant shall pay a pro rata monthly share [one-
twelfth (1/12) in the case of an entire Fiscal Year] of the estimated Utility
Costs for such Fiscal Year or partial Fiscal Year.

                     (ii) Within sixty (60) days after the end of each Fiscal
Year during the Term (beginning with the Fiscal Year in which the Commencement
Date occurs), or as soon thereafter as reasonably practical, Landlord shall
furnish to Tenant a statement of the actual Utility Costs for such Fiscal Year
("Utility Statement"), in reasonable detail so that Tenant can determine the
manner in which Landlord calculated the Utility Costs. Each Utility Statement
shall include, but not be limited to, a statement as to the relative numbers of
Btu's taken from or added to the stream of heated and chilled water delivered to
the air-handling units serving (i) the Premises, (ii) the common areas, and
(iii) all portions of the Building other than the Premises and common areas, and
the amounts of electricity costs allocated to such three respective portions of
the Building for the Fiscal year involved.

                     (iii)  Within thirty (30) days after the delivery of the
Utility Statement, Tenant shall make a lump sum payment to Landlord equal to the
amount, if any, by which the actual Utility Costs exceeds the estimated payments
toward Utility Costs paid by Tenant for such previous Fiscal Year.

                     (iv) If the actual Utility Costs is less than the estimated
payments toward Utility Costs paid by Tenant for such previous Fiscal Year,
Landlord shall refund the excess to Tenant within thirty (30) days after the
issuance of the Utility Statement or, at Landlord's option, Landlord shall apply
such amount to the next payments of Rental due hereunder.

                     (v)  The effect of the reconciliation payment or adjustment
pursuant to (iii) and (iv) above is that Tenant shall pay during each Fiscal
Year during the Term the actual Utility Costs.

                                     -14-
<PAGE>

                (c)  If the Commencement Date occurs on a date other than the
first day of a Fiscal Year, or the Term ends on a date other than the last day
of a Fiscal Year, then the actual Utility Costs incurred during such partial
Fiscal Year in which the Commencement Date or the Expiration Date, as
applicable, occurs shall be computed and an appropriate calculation shall be
made so that Tenant pays only the Utility Costs incurred during such partial
Fiscal Year.

                (d)  Within thirty (30) days after delivery of a Utility
Statement, Tenant shall have the right to notify Landlord that it intends to
examine Landlord's books and records with respect to such Utility Statement. If
Tenant so notifies Landlord, then Tenant and its representatives shall have the
right, at Tenant's expense during normal business hours for a period of ninety
(90) days after Tenant's notice, to examine Landlord's books and records with
respect to the calculation and determination of Utility Costs for the previous
Fiscal Year. Tenant shall notify Landlord within such ninety (90) day period if
it disputes such Utility Statement, setting forth the reasons therefor (a
"Notice of Dispute"). If Tenant either (i) fails to notify Landlord of its
intention to examine Landlord's books and records within thirty (30) days after
delivery of a Utility Statement, or (ii) fails to give Landlord a Notice of
Dispute within the ninety (90) day period of examination hereinabove referred
to, then Tenant shall be deemed to have accepted such Utility Statement for all
purposes hereunder. If Landlord shall have overstated Tenant's obligation for
Utility Costs for any Fiscal Year or partial Fiscal Year, Landlord shall
promptly refund such excess with interest at the Prime Rate from the date paid
by Tenant to the date refunded by Landlord.

        Section 8.02.  Landlord shall, at Landlord's expense, install, operate
        -------------
and maintain all necessary machinery and equipment to provide heated and chilled
water adequate to provide air-conditioning and heating to the Premises twenty-
four (24) hours per day, seven (7) days per week, at such temperatures and in
such amounts as are customarily provided to tenants occupying comparable space
(and operating twenty-four (24) hours per day) in first-class office buildings
in Washington, D.C., and in compliance with the specifications of Exhibit C-1.
While Tenant is occupying the Premises and is not in default under this lease,
Landlord shall furnish Tenant with the following services: (a) potable water and
heated water at those points of supply provided for normal lavatory use by
tenants in the Building; (b) heating, ventilating, and/or air conditioning in
the common and public areas of the Building twenty-four (24) hours per day,
seven (7) days per week, at such temperatures and in such amounts as may
customarily be provided to tenants occupying comparable space in first-class
office buildings (operating twenty-four hours per day) in Washington, D.C.

        Section 8.03.    At Landlord's expense, Landlord will provide feeders
        -------------
and risers to provide electrical current to the Building and to each of the
floors of the Premises in compliance with the specifications of Exhibit C-1. Any
additional riser or risers or wiring hereafter required to meet Tenant's excess
electrical requirements will, upon Tenant's written request, be installed by
Landlord at Tenant's sole cost (if the same are necessary and will not cause
permanent damage or injury to the Building or to the Premises or cause or create
a dangerous or hazardous condition, or entail excessive or unreasonable
alterations, repairs, or expense or interfere with or disturb other tenants or
occupants).

        Section 8.04.    Failure to furnish, or any stoppage of, the services
        -------------
provided for in Article 7 above and this Article 8 resulting from any cause will
not make Landlord liable in any

                                     -15-
<PAGE>

respect for damages to either person, property, or business, nor construed as an
eviction of Tenant, nor entitle Tenant to any abatement of rent, nor relieve
Tenant from its obligations under this lease. Should any malfunction of the
Building improvements or facilities occur, Landlord will repair such malfunction
promptly with reasonable diligence, but Tenant will have no claim for rebate,
abatement of rent or damages because of malfunctions or any interruptions in
service. Notwithstanding the foregoing, in the event of any such malfunction or
interruption in service which (i) is within Landlord's reasonable control to
remedy, (ii) renders the Premises untenantable to such extent that Tenant cannot
reasonably conduct its normal business operations in all or substantially all of
the Premises, and (iii) is continuous for ten (10) consecutive days, Rental
shall be abated for the period of time such malfunction or interruption in
service continues beyond such ten- (10) day period; and in addition, if any such
malfunction or interruption in service which (i) is within Landlord's reasonable
control to remedy, (ii) renders the Premises untenantable to such extent that
Tenant cannot reasonably conduct its normal business operations in all or
substantially all of the Premises, and (iii) is continuous for ninety (90)
consecutive days (which ninety- (90) day period shall be extended by force
majeure circumstances), the Tenant may, at its election, terminate this lease by
giving Landlord written notice of such election at any time thereafter prior to
the restoration of such services, in which event this lease shall terminate as
of the date of such notice, and except for those matters which specifically
survive termination hereof, the parties shall be relieved of all further
obligations and responsibilities under this lease.

                                   ARTICLE 9

                               REAL ESTATE TAXES

        Section 9.01.    Landlord believes that the Land and the INTELSAT
        -------------
Headquarters Building are not subject to the imposition of real estate taxes but
Landlord desires to provide for the payment by Tenant of its share of real
estate taxes in the event that by reason of a change in ownership of Landlord's
interest or otherwise any real estate taxes are imposed with respect to the Land
and/or the INTELSAT Headquarters Building.

        Section 9.02.    For purposes of this Article 9, the following terms
        -------------
shall have the following meanings:

                (a)  "Real Estate Taxes" shall mean all taxes, assessments, and
other governmental charges (including vault rentals, if any,) applicable to the
Land, the INTELSAT Headquarters Building, or any portion thereof, or to
Landlord's personal property used in connection with the maintenance and
operation thereof (not including any personal property used in connection with
Landlord's occupancy of any part of the INTELSAT Headquarters Building). In
addition, if at any time during the Term there shall be levied, assessed, or
imposed on Landlord or the Land and/or the INTELSAT Headquarters Building by any
governmental authority, any general or special ad valorem or other charge or tax
directly upon rentals received under leases covering space in the INTELSAT
Headquarters Building, or if any fee, tax, assessment or other charge is imposed
which is measured by or based, in whole or in part, upon such rents, or if any
charge or tax is made based directly or indirectly upon the transactions
represented by leases covering space in the INTELSAT Headquarters Building, or
the occupancy or use thereof, such taxes, fees, assessments, or other charges
shall be included as "Real Estate

                                     -16-
<PAGE>

Taxes;" provided, however, that any inheritance, estate, gift, franchise,
corporation, income, excess profit, transfer, net profits tax, sales tax or
excise tax (other than those specified in Section 9.03, which shall not be
included in the term Real Estate Taxes, but which Tenant shall pay directly to
the extent provided in Section 9.03), or special assessments for public
improvements, which may be assessed against Landlord shall be excluded from
"Real Estate Taxes;" and provided, further, that any amount of any tax which is
borne by any other tenant or is reimbursed to Landlord by any other tenant other
than under a rental adjustment provision of such tenant's lease corresponding
generally to this Article 9 shall be excluded from "Real Estate Taxes" (as, for
example and not by way of limitation, taxes assessed against particular
leasehold improvements or other facilities, alterations constructed or installed
by a tenant and which such tenant is required to bear and pay or for which such
tenant is required to pay specific reimbursement to Landlord).

                (b)  "Tax-Qualified Area" shall mean all rentable space in the
INTELSAT Headquarters Building which, for the tax year in question, is exempt
from Real Estate Taxes.

                (c) "Non-Tax-Qualified Area" shall mean all rentable space in
the INTELSAT Headquarters Building other than space which is Tax-Qualified Area.

                (d)  "Per Square Foot Amount of Base Real Estate Taxes" shall
mean the sum of (i) Two Dollars and fifty cents ($2.50) and (ii) sixty percent
(60%) of the amount by which (A) the annualized Per Square Foot Amount of Real
Estate Taxes for the first tax year during which Real Estate Taxes are assessed
upon any Non-Tax-Qualified Area exceeds (B) Two Dollars and fifty cents ($2.50).

                (e)  "Per Square Foot Amount of Real Estate Taxes" for any tax
year shall mean the quotient derived by dividing (i) the Real Estate Taxes for
such tax year, by (ii) the number of square feet of Rentable Area of the
INTELSAT Headquarters Building that is Non-Tax-Qualified Area for such tax year;
provided, however, that, if the Real Estate Taxes which are imposed upon or
assessed against or with respect to or based on the value of the Land (as
distinguished from the Non-Tax-Qualified Area of the INTELSAT Headquarters
Building) reflect an amount that would be payable if there were no tax-exempt
organizations or other entities occupying space in the INTELSAT Headquarters
Building, then the "Per Square Foot Amount of Real Estate Taxes" for such tax
year shall mean the sum of (i) the quotient derived by dividing (A) the Real
Estate Taxes for such tax year, less all amounts, if any, of such Real Estate
Taxes which are imposed upon or assessed against or with respect to or based on
the value of the Land (as distinguished from the Non-Tax-Qualified Area of the
INTELSAT Headquarters Building), by (B) the number of square feet of Rentable
Area of the INTELSAT Headquarters Building that is Non-Tax-Qualified Area for
such tax year, plus (ii) the quotient derived by dividing (A) the amount, if
any, of the Real Estate Taxes for such tax year which are imposed upon or
assessed against or with respect to or based on the value of the Land (as
distinguished from the Non-Tax-Qualified Area of the INTELSAT Headquarters
Building), by (B) the number of square feet of Rentable Area of the entire
INTELSAT Headquarters Building.

                (f)  "Tenant's Proportionate Tax Share" for any tax year shall
mean the product of (i) the number of square feet of Rentable Area of the
Premises that is Non-Tax-

                                     -17-
<PAGE>

Qualified Area for such tax year, times (ii) the excess, if any, of the Per
Square Foot Amount of Real Estate Taxes for such tax year over the Per Square
Foot Amount of Base Real Estate Taxes.

        Section 9.03.  During the Term Tenant shall pay to Landlord, as
        -------------
additional rent, Tenant's Proportionate Tax Share. In the event that sales tax
or excise tax is imposed by any governmental authority on the rent payable by
Tenant hereunder, such sales tax or excise tax shall be paid by Tenant. Landlord
shall submit to Tenant a copy of the bill for Real Estate Taxes and a statement
of Tenant's Proportionate Tax Share. Tenant shall pay Tenant's Proportionate Tax
Share for the tax year to which such amount applies, in the same number of
installments as the Real Estate Taxes are payable to the taxing authority
payable in said year, at least thirty (30) days prior to the due date for each
such installment.

        Section 9.04.    If the Commencement Date or the Expiration Date does
        -------------
not coincide with the first or last day of a tax year, respectively, then, with
respect to the tax year in which such Commencement Date or Expiration Date
occurs, Tenant's Proportionate Tax Share shall be prorated based upon the number
of days in such tax year during which this lease is in effect. If Landlord
receives any refunds of Real Estate Taxes for a tax year falling wholly or
partly within the Term, Landlord shall promptly recompute Tenant's Proportionate
Tax Share and deliver to Tenant a statement showing such recomputation together
with interest, if any, received by Landlord from the taxing authorities on the
amount of such overpayment. Within ten (10) days after the later of (i) the date
on which Landlord's right to such refund becomes final or (ii) the date on which
Landlord receives such refund, Landlord shall refund to Tenant any overpayment
of Tenant's Proportionate Tax Share for the tax year in question, together with
interest, if any, received by Landlord from the taxing authorities on the amount
of such overpayment, together with interest on such overpayment at the Prime
Rate per annum for any period after Landlord received such tax refund to the
date when Landlord remits such overpayment to Tenant. The fact that Landlord
might become obligated to make a refund to Tenant at some future time shall not
cure any default by Tenant in failing to make timely payments of its liability
for Tenant's Proportionate Tax Share.

        Section 9.05.    For Purposes hereof, the Rentable Area of the INTELSAT
        -------------
Headquarters Building shall be determined in accordance with Exhibit E.

                                  ARTICLE 10

                          USE AND LEGAL REQUIREMENTS

     The Premises shall be used only for the operation of a television broadcast
station and related studio and office space and for no other purpose.  If at any
time Tenant shall be prohibited by "Legal Requirements", or by virtue of any
provision of the Ground Lease from (i) using the Premises for the operation of a
television broadcast station and related studio and office space (which
prohibition cannot be remedied by a commercially feasible change in Tenant's
method of operation), or (ii) installing, operating or maintaining the
Communication Systems and there are no commercially feasible alternative systems
performing comparable functions that can be installed by Tenant, Tenant shall
have the right, at is election, by giving written notice of termination to
Landlord, to terminate this lease, in which event the Term of this lease will
end on the date of giving of such notice to Landlord with the same effect as if
such date were the

                                     -18-
<PAGE>

Expiration Date elsewhere herein defined. Tenant agrees to use and maintain the
Premises in a clean, careful, safe, lawful, and proper manner. Tenant shall, at
its sole expense (i) comply with all valid laws, orders, ordinances, regulations
applicable to the Premises of Federal, state, county, municipal and other
authorities ("Legal Requirements"), (ii) comply with any direction made pursuant
to law by any public officers requiring abatement of any nuisance, or which
imposes upon Landlord or Tenant any duty or obligation arising from tenant's
occupancy or use of the premises from conditions which have been created by or
at the insistence of Tenant, and (iii) indemnify Landlord and hold Landlord
harmless from any loss, cost, which Landlord may incur or suffer by claim, or
expense reason of Tenant's failure to comply with its obligations under clauses
(i) or (ii) above. If Tenant receives notice of any such direction or of
violation of any such law, order, ordinance, or regulation, it shall promptly
notify Landlord thereof.

                                  ARTICLE 11

                      OBSERVANCE OF RULES AND REGULATIONS

     Tenant and its servants, employees, agents, visitors, and licensees shall
observe faithfully and comply with the Rules and Regulations (herein so called)
attached to this lease as Exhibit F.  Landlord shall at all times have the right
to make reasonable changes in and additions to such Rules and Regulations,
provided such changes in existing or new Rules and Regulations do not materially
interfere with the lawful conduct of Tenant's business in the Premises.  Any
failure by Landlord to enforce any of the Rules and Regulations now or hereafter
in effect, either against Tenant or any other tenant in the Building, shall not
constitute a waiver of any such Rules and Regulations.  Landlord shall not be
liable to Tenant for the failure or refusal by any other tenant, guest, invitee,
visitor, or occupant of the Building to comply with any of the Rules and
Regulations.  Anything herein contained to the contrary notwithstanding, in the
event any Rule or Regulation is not enforced in a uniform and non-discriminatory
manner, such Rule or Regulation shall not be enforceable against Tenant.

                                  ARTICLE 12

                                  ALTERATIONS

        Section 12.01.      Tenant may not, at any time during the Term, without
        --------------
Landlord's prior written consent, make any alterations to the Premises which (i)
in Landlord's judgment affect the structure or the safety of the Building, (ii)
in Landlord's judgment affect the Building electrical, HVAC, plumbing or
mechanical systems or the functioning thereto outside the Premises, (iii) in
Landlord's judgment fail to comply with applicable Legal Requirements or (iv)
front upon or are located Within twelve (12) inches from any window (other than
any walls which join any window or exterior wall). If Tenant desires to make any
alterations in or to the Premises, Tenant shall, prior to beginning any such
work, deliver to Landlord all plans or drawings and specifications therefor,
whether or not Landlord's approval is recurred for such alterations. If
Landlord's approval is required pursuant to the first sentence of this Section
12.01, Tenant shall nay to Landlord reasonable costs incurred by Landlord for
third-party consultants to review such plans and specifications. Tenant may
proceed to the construction of the alterations provided that (i) Tenant has
received Landlord's approval thereof, if required pursuant to the first sentence
of this Section 12.01, (ii) the alterations are in strict compliance with the
plans and

                                     -19-
<PAGE>

specifications submitted to Landlord and with the provisions of this Article 12;
(iii) Tenant Shall indemnify and hold Landlord harmless against and from any and
all claims, damages, costs and finest arising out of or connected with such
alterations, and (iv) Tenant shall procure at its own expense such governmental
approvals and permits as may be required for such alterations. Landlord shall
exercise reasonable good faith judgment in determining whether to approve the
plans and specifications, it being understood and agreed that if a dispute
should arise as to whether Landlord's disapproval of any plans and
specifications was exercised in Landlord's reasonable good faith judgment,
Landlord shall have no liability because of such disapproval until such time as
(i) a court of competent jurisdiction enters a final judgment not subject to
further appeal that Landlord did not exercise reasonable good faith judgment in
withholding its approval and (ii) after such final determination Landlord
continues to refuse to consent to the applicable plans and specifications. Where
Landlord's approval is required pursuant to the first sentence of this Section
12.01, such approval shall be conclusively deemed to have been granted unless
Landlord gives Tenant written notice specifying in particular its objections to
such plans and specifications within fifteen (15) days after Landlord has
received Tenant's plans or drawings and specifications for any alterations, but
only if at the time Tenant delivers the plans or drawings and specifications to
Landlord, Tenant notifies Landlord in writing that if Landlord fails to respond
within fifteen (15) days, such silence shall be deemed an approval. At Tenant's
expense, Landlord shall join in submitting Tenant's plans for any necessary
governmental approval, if required by applicable law. All alterations shall be
made at Tenant's expense by contractors which have been approved by Landlord
(which approval shall not be unreasonably delayed or withheld). All such
construction, alterations, and maintenance work done by, or for, Tenant shall
(A) be performed in a such manner as to maintain harmonious labor relations, (B)
not alter the exterior appearance of the Building or the common and public areas
thereof, (C) not affect the structure or the safety of the Building, (D) comply
with all building, safety, fire, plumbing, electrical, and other codes and
governmental and insurance requirements, (E) be completed promptly and in a good
and workmanlike manner, and (F) be performed in compliance with Article 13
hereof.

        Section 12.02.   After the completion of any alterations to the
        --------------
Premises, Tenant shall deliver to Landlord either (i) a certificate signed by
Tenant stating that such alterations have been completed in accordance with the
plans and specifications previously delivered to Landlord or (ii) a copy of "as-
built" plans and specifications with respect to such alterations.

        Section 12.03.   No alterations, leasehold improvements, and other
        --------------
physical additions made or installed by or for Tenant in or to the Premises
shall be removed during the Term except, in accordance with Section 20.02.

                                  ARTICLE 13

                                     LIENS

     Tenant shall keep the Premises and the Building free from any liens arising
from any work performed, materials furnished, or obligations incurred by or at
the request of Tenant.  All persons either contracting with Tenant's, furnishing
or rendering labor and materials to Tenant shall be notified in writing by
Tenant that they must look only to go thing contained in this lease shall be
construed as Landlord's consent to any contractor, subcontractor, laborer, or

                                     -20-
<PAGE>

materialman" or the performance of any labor or the furnishing of any materials
for any specific improvement, alteration, or repair of, or to, the Premises or
the Building, nor as giving Tenant any right to contract for, or permit the
performance of, any services or the furnishing of any materials that would
result in any liens against the Premises or the Building.  If any lien is filed
against the Premises or Tenant's leasehold interest therein, or if any lien is
filed against the Building which arises out of any purported act or agreement of
Tenant, Tenant shall discharge the same within ten (10) days after its filing by
payment, filing of the bond required by law; or otherwise.  If Tenant fails t o
discharge such lien within such period, then, in addition to any other right or
remedy of Landlord, Landlord may, at its election, discharge the lien by paying
the amount claimed to be due, by obtaining the discharge by deposit with a court
or a title company, or by bonding.  Tenant shall pay on demand any amount paid
by Landlord for the discharge or satisfaction of any such lien, and all
reasonable attorneys' fees and other costs and expenses of Landlord incurred in
defending any such action or in obtaining the discharge of such lien, together
with all necessary disbursements in connection therewith.

                                  ARTICLE 14

                                    REPAIRS

        Section 14.01.   Tenant shall keep the Premises and every part thereof
        --------------
in good condition and repair at all times during the Term and at Tenant's sole
cost and expense. If Tenant fails to make such repairs promptly, Landlord, at
its option, may make such repairs, and Tenant shall pay Landlord on demand
Landlord's actual costs in making such repairs. Notwithstanding the foregoing,
Tenant shall have no obligation to maintain or repair any portion of the
Building which is not part of the Premises; provided, however, that Tenant shall
reimburse Landlord for any actual costs incurred for maintenance or repair of
any such portion of the Building if such maintenance or repair is necessitated
by the negligent acts or omissions of Tenant. At the end of the Term, Tenant
shall surrender to Landlord the Premises and all alterations, additions and
improvements thereto subject to the provisions of Article 20 hereof. Landlord
has no obligation and has made no promise to alter, remodel, improve, repair,
redecorate, or paint the Premises or any part thereof, except as specifically
set forth in this lease. No representations respecting the condition of the
Premises or the Building have been made by Landlord to Tenant except as
specifically set forth in this lease.

        Section 14.02.
        --------------

                (a)  Subject to the other provisions of this lease imposing
obligations in this respect upon Tenant, and subject to the provisions of
Articles 16 and 17 hereof, Landlord shall repair, replace, and maintain (i) the
external and structural parts of the Building, (ii) all common and public areas
of the Building (including the parking garage), and (iii) the HVAC, mechanical,
electrical and plumbing systems of the Building exclusive of systems, if any,
specially installed by or on behalf of any tenant; provided that, the HVAC,
mechanical, electrical and plumbing systems of the Building to be installed by
Landlord under the terms of this lease or under the terms of Exhibit C hereto
shall not be deemed to have been "specially installed by or on behalf of any
tenant" for purposes of this Section 14.02 (other than the supplemental air-
conditioning chiller which Landlord shall initially install for Tenant at
Landlord's cost and expense, which chiller Tenant shall maintain and repair
during the Term but need not replace).

                                     -21-
<PAGE>

                (b)  Nothing contained in this Section 14.02 shall preclude
Landlord from including in Basic Costs (pursuant to Sections 6.02 and 6.03) any
of the costs and expenses referred to herein to the extent the same are within
the definition of Basic Costs.

                                  ARTICLE 15

                                   INSURANCE

        Section 15.01.    During the Term, Tenant, at its sole expense, shall
        --------------
obtain and keep in force the following insurance:

                (a)  All Risk insurance upon property of every description and
kind owned by Tenant and located in the Building owned by Tenant and located in
the Building or for which Tenant is legally liable or installed by or on behalf
of Tenant, including without limitation, furniture, fittings, installations,
furnishings, movable trade fixtures and personal property, and alterations, in
an amount not less than ninety percent, (90%) of the full replacement cost
thereof. All such insurance policies shall contain a waiver of subrogation in
favor of Landlord. Landlord will not be required to carry insurance of any kind
on any of Tenant's fixtures, equipment or improvements under this lease, and
Landlord shall not be obligated to repair any damage thereto or replace the
same. Tenant shall also maintain All Risk insurance covering all Non-Building
Standard Lease hold Improvements in an amount equal to not less than ninety
percent (90%) of the replacement cost thereof in excess of the replacement cost
of corresponding Building Standard Leasehold Improvement containing a waiver of
subrogation in favor of Landlord. As such term is used herein, "Building
Standard Leasehold Improvements" shall refer to leasehold improvements of the
nature and quality of the leasehold improvements heretofore installed by
Landlord in the portions of the Phase I buildings on the Land.

                (b)  Comprehensive general liability insurance coverage,
including personal injury, bodily injury, broad form property damage, operations
hazard, owner's protective coverage, contractual liability, and products and
completed operations liability, in limits not less than $5,000,000 inclusive
provided that such $5,000,000 limits may be reduced to the extent that insurance
coverage in such amount becomes unobtainable at commercially reasonable rates or
to the extent that lesser limits are, in the future, customarily maintained by
parties similarly situated and comparable to Tenant engaged in business in
Washington, D.C. All such insurance policies shall name Tenant as named insured
thereunder and shall name Landlord and Landlord's mortgagees (and, if requested
by Landlord, ground or primary lessors) as additional insureds thereunder, all
as their respective interests may appear. Such insurance may be placed as part
of any blanket policy carried by Tenant and/or carried under primary and excess
coverage policies.

                (c)  Worker's Compensation and Employer's Liability insurance as
required by law.

                (d)  Any other form or forms of insurance as Tenant, Landlord or
Landlord's mortgagee may reasonably from time to time in form, in amounts and
for insurance risks against which a prudent tenant of comparable size and in
comparable business would protect itself.

                                     -22-
<PAGE>

     All policies shall be issued by insurers of recognized responsibility.
Tenant will deliver certificates of insurance (substantially in the form of
Exhibit E hereto) to Landlord as soon as practicable after the placing of the
required insurance, but not later than ten (10) days prior to the date Tenant
takes possession of all or any part of the Premises.  All policies shall contain
an undertaking by the insurers to notify Landlord and Landlord's mortgagees
(and, if applicable, ground lessors) in writing, by certified or registered
United States mail, return receipt requested, not less than fifteen (15) days
before any material adverse change, reduction in coverage, cancellation, or
other termination thereof.

        Section 15.02.  During the Term, Landlord shall insure the Building
        --------------
Standard Leasehold Improvements (excluding any property Tenant is obligated to,
insure under Section 15.01 hereof) with a reputable insurance company against
damage with All Risk insurance in an amount not less than 90% of the then
replacement cost and Landlord shall also insure the Non-Building Standard
Leasehold Improvements that are of a similar, type, character and nature as
Building Standard Leasehold Improvements with a reputable insurance company with
All Risk Insurance in an amount not less than 90% of the full replacement cost
of those Building Standard Leasehold Improvements of a similar type, character
and nature. (All such insurance policies shall contain waive of subrogation in
favor of Tenant. Landlord shall also maintain comprehensive general liability
insurance in limits not less than the liability insurance limits required to be
maintained by Tenant pursuant to Section 15.01(b) from time to time, which
insurance policies shall waive any right of the insurer to invoke any privilege
or immunity (as an International Organization or sovereign government) of
Landlord, and shall name Tenant as an additional insured thereunder. Landlord
may, but shall not be obligated to, obtain and carry any other form or forms of
insurance as it or Landlord's mortgagees may reasonably determine advisable.
Notwithstanding any contribution by Tenant to the cost of insurance premiums, as
provided herein, Tenant acknowledges that it has no right to receive any
proceeds from any property insurance policies carried by Landlord.

        Section 15.03.   Tenant will not keep or use in or upon the Premises any
        --------------
article which may be prohibited by any insurance policy in force covering the
Building and the leasehold improvements in the Building. If Tenant's occupancy
or business in or on the Premises, whether or not Landlord has consented to the
same, results in any increase in premiums for the insurance carried by Landlord
with respect to the Building, Tenant shall pay any such increase in premiums as
additional Rental within ten (10) days after being billed therefor by Landlord.
In determining whether increased premiums are a result of Tenant's use of the
Premises, a schedule issued by the organization computing the insurance rate on
the Building or the leasehold improvements showing the various components of
such rate shall be conclusive evidence of the several items and charges which
make up such rate. Tenant shall promptly comply with all reasonable requirements
of the insurance authority or any present or future insurer relating to the
Premises. Nothing herein shall, however, be construed to prohibit Tenant from
keeping and using in the Premises any equipment or property reasonably and
customarily used for the operation of a television broadcast station and related
studio and office.

        Section 15.04.   If any of Landlord's insurance policies shall be
        --------------
cancelled or cancellation shall be threatened or the coverage thereunder reduced
or threatened to be reduced in any way because of the use of the Premises or any
part thereof by Tenant or any assignee or subtenant of Tenant or by anyone
Tenant permits on the Premises and if Tenant fails to remedy

                                     -23-
<PAGE>

the condition giving rise to such cancellation, threatened cancellation,
reduction of coverage, or threatened reduction of coverage within a reasonable
period of time after notice not to exceed ten (10) days (or such longer period
of time as is required to remedy such condition provided Tenant commences to
correct such condition within such ten- (10) day period and continues diligently
to remedy such condition to completion), Landlord may, at its option, enter upon
the Premises and attempt to remedy such condition, and Tenant shall promptly pay
the cost thereof to Landlord as additional Rental. Landlord shall not be liable
for any damage or injury caused to any property of Tenant or of others located
on the Premises resulting from such entry. If Landlord is unable, or elects not,
to remedy such condition, then Landlord shall have all of the remedies provided
for in this lease in the event of a default by Tenant. Notwithstanding the
foregoing (but subject to Section 15.03), Landlord shall be responsible for
maintaining insurance, if available, which permits Tenant to make reasonable use
of the Premises for the normal operation of a television broadcast station and
related studio and office space without regard to the foregoing provisions of
this Section 15.04, provided, however, that if Landlord is unable to obtain such
insurance and if Landlord elects not to self-insure in accordance with Section
15.06, Landlord shall have the right to terminate this lease by notifying Tenant
of such election in writing in which event, this lease shall be terminated as of
the date specified in such notice, and except for provisions hereof which
expressly survive termination, the parties shall have no further liabilities or
responsibilities under this lease.

        Section 15.05.      All policies covering real or personal property
        --------------
which either party obtains affecting the Premises or the Building shall include
a clause or endorsement denying the insurer any rights of subrogation against
the other party to the extent rights have been waived in writing by the insured
before occurrence of injury or loss. Landlord and Tenant shall not be liable or
responsible for, and each hereby releases the other, the partners, employees,
officers, directors and agents of the other from any and all liability and
responsibility to the other, or any and each hereby releases the other, the
partners, employees, officers, directors and agents of the other from any and
all liability and responsibility to the other, or any person claiming by,
through or under the Landlord or Tenant, by way of subrogation or otherwise for
any damage or loss to their respective property due to hazards covered or which
should be covered by policies of insurance obtained or which should be or have
been obtained pursuant to this lease, to the extent of the injury or loss
covered or which should have been covered thereby, assuming that any deductible
shall be deemed to be insurance coverage.

        Section 15.06.   So long as (i) International Tele-communications
        --------------
Satellite Organization is the Landlord hereunder (and has not suffered a
material and adverse change in its financial condition or strength), or (ii) if
the Landlord hereunder is not International Telecommunications Satellite
Organization but demonstrates to Tenant's reasonable satisfaction that Landlord
has sufficient financial strength to absorb such risk, and with Tenant's prior
consent in writing (such consent not to be unreasonably withheld), then Landlord
may elect to self-insure (and not obtain from an insurance company) all or part
of the property insurance required to be maintained by Landlord under the
provisions of the first, sentence of Section 15.02; provided that, to the extent
that Landlord does self-insure against any risk or hazard, Landlord hereby
releases Tenant and the partners, employees, officers, directors and agents of
Tenant, and agrees to indemnify and save and hold Tenant and its partners,
employees, officers, directors and agents harmless from any loss, cost, expense,
claim or liability whatsoever in connection with any damage or loss to any
property of Landlord due to hazards or risks which would have been covered by
policies of

                                     -24-
<PAGE>

insurance which would have been required to be maintained by Landlord under the
provisions of Section 15.02 had it not elected to self-insure against such risk
or hazard.

                                  ARTICLE 16

                       DAMACE BY FIRE OR OTIHER CASUALTY

        Section 16.01.   If the Building or the Premises shall be damaged by any
        --------------
casualty, Tenant shall immediately notify Landlord of the same and if this lease
shall not have been terminated pursuant to this Article 16, Landlord shall
repair said damage and restore and rebuild the Building and/or the Premises
(including leasehold improvements in the Premises, but excluding the property of
Tenant, and limited to the cost of repairing, restoring or rebuilding Building
Standard Leasehold Improvements in the case of Non-Building Standard Leasehold
Improvements) as soon as reasonably practicable after said damage occurs, and
the Rental payable hereunder shall be reduced or abated in proportion to the
extent that the Premises are rendered unusable for the normal conduct of the
business then conducted on the Premises until such Premises are rendered usable
for the normal conduct of such business.

        Section 16.02.   If the Premises shall be damaged or destroyed by any
        --------------
casualty such that Landlord reasonably estimates that the repair and restoration
of the Premises would require an expenditure of more than twenty-five percent
(25%) of the replacement cost of the Premises immediately prior to such
casualty, and if (i) less than three (3) years remain of the unexpired term of
this lease (as theretofore extended, if applicable) or (ii) Landlord elects to
demolish the Building (or the two (2) Pods of the Building containing the
Premises), then Landlord shall have the right to terminate this lease by written
notice to Tenant given within sixty (60) days after the date of such damage and
upon such notice this lease shall terminate; provided, however, that the
provisions of this lease which are designated to cover matters of termination
and the period thereafter shall survive the termination of this lease.

        Section 16.03.   If the Building and/or the Premises shall be so damaged
        --------------
by casualty to such extent that the premises are rendered unusable for the
normal conduct of Tenant's business then conducted on the Premises, Landlord
shall, as promptly as practicable following such casualty, obtain and deliver to
Tenant a certificate by an independent, qualified engineer or contractor setting
forth the good faith reasonable estimate of such engineer or contractor as to
the period of time required to substantially repair and restore the Building
and/or Premises so as to permit Tenant to resume the normal conduct of its said
business in the Premises. In such event:

                (a)  If such certificate reflects that such repair and
restoration cannot reasonably he completed within one hundred eighty (180) days
after the occurrence of such casualty, and if at least two (2) years remain of
the Term of this lease (including any extension of such Term as to which Tenant
has theretofore exercised an option so to extend the Term), Tenant may terminate
this lease by giving written notice of termination to Landlord within thirty
(30) days after receipt of such certificate.

                (b)  If such certificate reflects that such repair and
restoration cannot reasonably be completed within ninety (90) days after
occurrence of such casualty, and if less than two (2) years remain of the Term,
of this lease (including any extension of such Term as to

                                     -25-
<PAGE>

which Tenant has theretofore exercised an option so to extend the Term), Tenant
may terminate this lease by giving written notice of termination to Landlord
within thirty (30) days after receipt of such certificate.

                (c)  If such certificate reflects that such repair and
restoration cannot reasonably be completed within one hundred eighty (180) days
after the occurrence of such casualty, and if at least two (2) years remain of
the Term of this lease (including any extension of such Term as to which Tenant
has theretofore exercised an option so to extend the Term), and if Landlord
elects to demolish the Building (or the two Pods of the Building containing the
Premises), Landlord may terminate this lease by giving written notice of
termination to Tenant within forty-five (45) days after the occurrence of such
casualty.

                (d)  If such certificate reflects that such repair and
restoration cannot reasonably he completed within ninety (90) days after the
occurrence of such casualty, and if less than two (2) years remain of the Term
of this lease (including any extension of such Term as to which Tenant has
theretofore exercised an option so to extend the Term), Landlord may terminate
this lease by giving written notice of termination to Tenant within forty-five
(45) days after occurrence of such casualty.

     If this lease is terminated pursuant to any of the foregoing provisions of
this Section 16.03, the provisions of this lease which are designated to cover
matters of termination and the period thereafter shall survive the termination
of this lease.

        Section 16.04.  If Landlord is obligated to repair the Premises or
        --------------
Building after any casualty pursuant to this Article 16, Landlord shall
diligently commence and continuously prosecute such repair to completion.

        Section 16.05.   If the Premises, or any substantial portion thereof, is
        --------------
substantially destroyed by fire or other cause at any time during the last
twelve (12) months of the Term (as the same may have been extended), either
Landlord or Tenant may terminate this lease upon written notice to the other
given within sixty (60) days after the date of such destruction, provided,
however, that those provisions of this lease which are designated to cover
matters of termination and the period thereafter shall survive the termination
hereof. For purposes of this Section 16.05, the Premises shall be deemed
"substantially destroyed" if at least twenty-five percent (25%) of the Rentable
Area of the Premises is rendered unusable by such fire or other cause.

        Section 16.06.   No damages, compensation, or claim shall be payable by
        --------------
Landlord for inconvenience, loss of business, or annoyance arising from any
repair or restoration of any portion of the Premises, the Leasehold
Improvements, or the Building. Landlord shall use its best efforts to have such
repairs made promptly so as not to unnecessarily interfere with Tenant's
occupancy.

        Section 16.07.   The provisions of this Article shall be considered an
        --------------
express agreement governing any case of damage or destruction of the Building,
the Leasehold Improvements, or the Premises by fire or other casualty.

                                     -26-
<PAGE>

        Section 16.08.   In the event of the termination of this lease pursuant
        --------------
to the provisions of Sections 16.02, 16.03 or 16.05, this lease, the Term and
the estate hereby granted shall expire as . of the date of such termination in
the same manner and with the same effect as if it were the date set for the
normal expiration of the Term, and Rental shall be apportioned as of the date of
termination.

                                  ARTICLE 17

                                 CONDEMNATION

        Section 17.01.   In the event the whole or substantially the whole of
        --------------
the Building and/or the Premises are taken or condemned for any public purpose,
this lease shall terminate as of the date of such taking; provided, however,
that those provisions of this lease which are designated to cover matters of
termination and the period thereafter shall survive the termination hereof.

        Section 17.02.   In the event that more than fifteen percent (15%) of
        --------------
the Rentable Area of the Premises shall be taken or condemned for any public or
quasi-public purpose, which taking, in Tenant's reasonable judgment, will
interfere materially with Tenant's normal conduct of Tenant's business in the
Premises, then Tenant shall have the option to terminate this lease, effective
as of the date specified by Tenant in its notice of termination; provided,
however, that those provisions of this lease which are designated to cover
matters of termination and the period thereafter shall survive the termination
hereof.

        Section 17.03.   In the event that a portion, but less than
        --------------
substantially the whole, of the Premises should be taken or condemned for any
public purpose, then this lease shall terminate as of the date of such taking as
to the portion of the Premises so taken, and, unless Tenant exercises its option
to terminate this lease pursuant to Section 17.02, this lease shall remain in
full force and effect as to the remainder of the Premises and Landlord shall
with due diligence restore the remainder of the Premises to an architectural
unit as nearly like its condition as it existed prior to such taking as is
reasonably and practicably feasible. In such event, the Annual Rental, Tenant's
Proportionate Share of Basic Costs Excess and Tenant's Proportionate Tax Share
of Real Estate Taxes attributable to the Premises will be diminished by an
amount representing the part of such amounts properly applicable to the portion
of the Premises so taken. Further, in such event, Tenant's Proportionate Share
shall be recomputed based upon the remaining Rentable Area in the Premises and
in the Building, but the area in the Building thus taken shall continue to be
considered as Rentable Area of the Building.

        Section 17.04.   In the event of the termination of this lease pursuant,
        --------------
to the provisions of Sections 17.01, 17.02 or 17.03, this lease and the Term and
the estate hereby granted shall expire as of the date of such termination in the
same manner and with the same effect as if that were the date set for the normal
expiration of the Term, and Rental shall be apportioned as of the date of
termination. The pro-visions of this Section 17.04 shall apply in the same
manner to any partial termination this lease pursuant to the provisions of this
Article 17.

        Section 17.05.   If Landlord is obligated to repair or restore the
        --------------
Premises or the Building after any taking or condemnation pursuant to this
Article 17, Landlord shall diligently and continuously prosecute such repair or
restoration to completion.

                                     -27-
<PAGE>

        Section 17.06.   Except as otherwise provided in Section 17.07 below,
        --------------
Landlord shall be entitled to receive the entire award in any condemnation
proceeding or action for taking of the Building, Land or Premises; provided that
Tenant shall be entitled to seek and recover and retain out of the award in any
such proceeding or action damages and compensation (i) for the value of any
leasehold improvements, additions or alterations installed or constructed in the
Premises or on the Building or Land by Tenant (less the portion, if any, thereof
for which Tenant was reimbursed by Landlord pursuant to this lease) and taken in
such proceeding or action, and (ii) for the value of any property of Tenant
other than the leasehold interest of Tenant taken in such proceeding or action.

        Section 17.07.   If the temporary use or occupancy of all or any part of
        --------------
the Premises shall be condemned or taken for any public or quasi-public use
during the Term, and if more than fifteen percent (15%) of the Rentable Area of
the Premises shall be so taken, which taking, in Tenant's reasonably judgment,
will interfere materially with Tenant's normal conduct of Tenant's business in
the Premises and such temporary taking shall be for a period in excess of one
(1) year or for the entire unexpired portion of the Term (as theretofore
extended, if applicable), then Tenant shall have the option to terminate this
lease, effective as of the date specified by Tenant in its notice of
termination; provided, however, that those provisions of this lease which are
designated to cover matters of termination and the period thereafter shall
survive the termination hereof. If the temporary use or occupancy of a portion
only of the Premises shall be so taken and this lease is not terminated by
Tenant pursuant to the foregoing provisions of this Section 17.07, Landlord
shall with due diligence restore the remainder of the Premises to an
architectural unit as nearly like its condition as it existed prior to such
taking as is reasonably feasible. In the event of any such condemnation or
taking, Tenant shall be entitled to appear, claim, prove and receive the portion
of the award for such taking that represents compensation for use or occupancy
of the Premises during the Term and damages for diminution in value or usability
of the remainder of the Premises during the Term (in case of a partial taking),
and Landlord shall be entitled to appear, claim, prove and receive the portion
of the award for such taking that represents compensation for the restoration of
the Premises and the use or occupancy of the Premises after the end of the Term
and damages for diminution in value or usability of the remainder of the
Premises after the Term (in case of a partial taking); provided that, if Tenant
shall terminate this lease as a consequence of such taking, Tenant shall remit
to Landlord so much of the award to Tenant (up to but not in excess of all
thereof) as shall equal (to the extent possible) the discounted present value
(discounted at the Prime Rate per annum as of the date of Tenant's receipt of
such award) of the Rental which would have accrued as to the portion of the
Premises so taken after such termination and during the period of such taking
(to, but not beyond, the end of the Term, as theretofore extended, if
applicable).

                                  ARTICLE 18

                           ASSIGNMENT AND SUBLETTING

                (a)  Except as hereinafter provided, Tenant may not sell,
assign, transfer, or hypothecate this lease or any interest herein or sublet the
Premises or any part thereof without prior written consent of Landlord, except
that Landlord's approval of any proposed sublease shall not be unreasonably
withheld. Landlord hereby consents to any assignment or sublease to any
corporation controlling, assignment or sublease to any corporation controlling,
controlled by,

                                     -28-
<PAGE>

or under common control with Tenant, or to any purchaser of all or substantially
all of the assets of Tenants. The parties agree that in the case of a proposed
sublease, it shall be reasonable for Landlord to withhold its approval if
Landlord determines in good faith that the proposed subtenant is nor financially
creditworthy, or is a medical or dental practice or is a user that will attract
a volume, frequency or type of visitor or employee to the Building which is not
consistent with the standards of a high quality office building or that will
impose an excessive demand or use on the facilities or services of the Building
or whose occupancy of the Premises would not be compatible with Landlord's
interests.

                (b)  If Tenant should desire to either (i) assign this lease or
(ii) sublet the Premises (or any part thereof), and provided that Tenant is not
then in default hereunder, Tenant shall give Landlord written notice at least
ninety (90) but no more than one hundred eighty (180) days in advance of the
date on which Tenant desires to make such assignment or sublease. Landlord shall
then have a period of thirty (30) days following receipt of such notice within
which to notify Tenant in writing that Landlord elects either (i) to permit
Tenant to assign or sublet such space, subject, however, to the subsequent
written approval of the proposed assignee or subtenant by Landlord; or (ii) to
refuse, in Landlord's sole and absolute discretion in the case of an assignment,
or in Landlord's reasonable discretion in the case of a subletting, to consent
to Tenant's assignment or subletting of such space and to continue this lease in
full force and effect as to the entire Premises. If Landlord fails to notify
Tenant in writing of such election within such thirty- (30) day period, Landlord
shall be deemed to have elected option (i) above. In the event that Tenant shall
sublease any portion or portions of the Premises with Landlord's consent (or
deemed consent) pursuant to this subsection 18.01(b), and if any such sublease
or subleases cover any period after the end of the fifth (5th) Lease Year
(herein called "Subject Subleases"), whether one or more, Tenant shall maintain
an account (the "Sublease Account") and shall enter debits and credits in such
Sublease Account and make payments (if any become due) of additional Rental to
Landlord as follows:

                     (i)  The Sublease Account shall be credited with the amount
of all rentals received by Tenant under and pursuant to all Subject Subleases,
including the reasonable value of any specific consideration paid to Tenant for
any such Subject Sublease in addition to "rental" paid thereunder.

                     (ii) The Sublease Account shall be debited with the amount
of all Rental paid by Tenant under this lease for or attributable to the
Rentable Area covered by each Subject Sublease during the term of such Subject
Sublease (except any additional Rental paid by Tenant to Landlord pursuant to
this subsection 18.01(b)).

                     (iii)  The Sublease Account shall be debited with all
direct costs and expenses incurred by Tenant in connection with entering into,
performing its obligations under and enforcing each such Subject Sublease,
including, without limitation, brokerage fees and commissions, legal fees,
accounting fees, costs and expenses of renovating or altering and maintaining
the portion of the Premises occupied or to be occupied or used by the subtenant
under any such Subject Sublease to comply with the requirements of such Subject
Sublease, costs and expenses of electricity, heating and air-conditioning
provided by Tenant to the subleased areas covered by such Subject Subleases
(determined and allocated on a pro rata per square foot of Rentable Area basis
with reference to the costs and expenses incurred by Tenant

                                     -29-
<PAGE>

for electricity, heating and air-conditioning in the entire Premises), and (if
applicable) costs and expenses of janitorial service, cleaning or other services
provided by Tenant to the subleased areas covered by such Subject Subleases,
provided there is no duplication of any such costs or expenses otherwise debited
to such Sublease Account.

                     (iv) If one or more Subject Subleases are entered into
prior to the end of the fifth (5th) Lease Year, and if the aggregate credits to
the Sublease Account as of the end of the fifth (5th) Lease Year shall exceed
the aggregate debits to such Sublease Account as of such date, the Sublease
Account shall be debited on such date with the amount of such excess (so as to
cause the aggregate debits to equal the aggregate credits as of such date). The
allocation of rental from Subject Subleases entered into prior to the end of the
fifth (5th) Lease Year shall be commercially reasonable.

                     (v)  If at the end of any month commencing after the end of
the fifth (5th) Lease Year the aggregate credits to the Sublease Account shall
exceed the aggregate debits to the Sublease Account as of such date, Tenant
shall, within ten (10) days thereafter, pay to Landlord, as additional Rental
under this lease, an amount equal to fifty percent (50%) of such excess; and
incident to such payment the Sublease Account shall be debited with an amount
equal to one hundred percent (100%) of such excess.

                (c)  If Tenant notifies Landlord of Tenant's desire to assign
this lease or sublet the Premises, more than once in any twelve (12) month
period, Tenant shall pay to Landlord as additional Rental with the next due
monthly Rental the actual legal fees, if any, for outside counsel, incurred by
Landlord to have such proposed sublease or assignment reviewed and evaluated. No
assignment or subletting by Tenant shall relieve Tenant of Tenant's obligations
under this lease. Any attempted assignment or subletting by Tenant in violation
of the terms and provisions of this Section 18.01 shall be void.

        Section 18.02.  Landlord may sell, transfer, assign, and convey, all or
        --------------
any part of the Building and any and all of its rights under this lease, and in
the event Landlord assigns its rights under this lease, Landlord shall be
released from any further obligations hereunder, and Tenant agrees to look
solely to Landlord's successor in interest for performance of such obligations;
provided that, notwithstanding any such assignment by Landlord of its rights
under this lease, Landlord shall nevertheless be and remain liable and
responsible for performance of all Landlord's covenants and agreements contained
and set forth in Section 25.04 of this lease for and during the entire term of
this lease and any extension of such term herein provided for.

                                  ARTICLE 19

                                INDEMNIFICATION

     Tenant waives all claim against Landlord for damage to any property, or
injury to, or death of any person in, upon or about the Building, the Premises,
or the parking facilities in the Building arising at any time and from any cause
other than (i) by reason of the willful misconduct of Landlord its agents or
employees, or (ii) in the case of injury to or death of any person, by reason of
the negligence of Landlord, its agents or employees; and Tenant shall indemnify
Landlord and shall hold Landlord harmless from any damage to property or injury
to,

                                     -30-
<PAGE>

or death of any person arising from the use of the Building, the Premises, or
the parking facilities by Tenant or its agents, employees, representatives,
contractors or invitees, except such as is caused (i) by the willful misconduct
of Landlord, its agents or employees or (ii) in the case of injury to or death
of any person , by reason of the negligence of Landlord or employees. Without
limiting the generality of the foregoing, Landlord shall not be liable for any
injury or damage to persons or property resulting form fire, explosion, falling
plaster, steam, gas, electricity, water, rain, flood, snow, or leaks from any
part of the Premises or from the pipes, appliance, equipment, plumbing works,
roof, or subsurface of any floor or ceiling, or from the street or any other
place, or by dampness or any other cause whatsoever, unless caused (i) by
Landlord's willful misconduct or (ii) in the case of injury to or death of any
person, by reason of the negligence of Landlord, its agents or employees.
Landlord shall not be liable for any such damage caused by other tenants or
persons in the Building or by occupants of adjacent property thereto, or by the
public, or caused by any private, public, or quasi-public construction or other
work, including, but not limited to, any construction modification, or operation
of underground, ground-level or above-ground pedestrian tunnels, bridges,
walkways, or similar items. Tenant's foregoing indemnity obligation shall
include reasonable attorneys' fees, investigation costs, and expenses incurred
by Landlord from the first notice that any claim or demand has been made or may
be made, but only to the extent such fees, costs and expenses are not covered by
Landlord's insurance. The provisions of this Article 19 shall survive the
termination of this lease with respect to any damage, injury, or death occurring
before such termination. If Landlord is made a party to any litigation commenced
by or against Tenant or relating to this lease or to the Premises, and provided
that in any such litigation Landlord is not finally adjudicated to be at fault,
then Tenant shall pay all costs and expenses, including reasonable attorneys'
fees and court costs, incurred by or imposed upon Landlord because of any such
litigation, but only to the extent such fees, costs and expenses are not covered
by Landlords insurance, and the amount of all such costs and expenses, including
reasonable attorneys' fees and court costs, shall be a demand obligation owing
by Tenant to Landlord. Tenant shall have the right, at Tenant's sole cost and
expense, to participate in the defense of any such action or proceeding brought
in connection with any claim against Landlord by a third party and to
participate in the negotiations for the settlement thereof. Tenant may retain
attorneys for such purposes. If Landlord agrees to a settlement or compromise of
a claim with respect to which Tenant has agreed to indemnify Landlord under this
Article 19, which settlement would require Tenant to suffer any loss, damage or
injury, without Tenant's specific prior written consent to and approval of such
settlement or compromise, Tenant shall be released from its indemnity obligation
with respect to such claim.

                                  ARTICLE 20

                           SURRENDER OF THE PREMISES

        Section 20.01.   Upon the expiration of the Term or other termination of
        --------------
this lease for any cause whatsoever, Tenant shall peacefully vacate the Premises
in as good order and condition as the same were at the beginning of the Term or
may thereafter have been improved by Landlord or Tenant, reasonable use and wear
thereof and damage to the Premises or the leasehold improvements by fire or
other casualty or condemnation only excepted, provided that at Tenant's election
and at Tenant's cost and expense, Tenant may remove any decorative

                                     -31-
<PAGE>

improvements (such as chandeliers, built-in cabinets, etc.) installed by Tenant
in the Premises and Tenant shall repair any damage caused by such removal.
Should Tenant continue to hold the Premises after the termination of this lease,
whether the termination occurs by lapse of time or otherwise, such holding over,
unless otherwise agreed to by Landlord in writing, shall constitute and be
construed as a tenancy at will at a daily Rental equal to one-thirtieth (1/30)
of an amount equal to the monthly Fair Market Value Rate (as defined in Article
32) for the first thirty (30) days, and from and after thirty (30) days after
this lease has been terminated, at a daily Rental equal to 1/30th of an amount
equal to two times the monthly Fair Market Value Rate (as defined in Article
32), in each case, times the number of square feet of Rentable Area in the
Premises as of the date of termination and subject to all of the other terms set
forth herein except any right to renew this lease, but the foregoing shall not
constitute a consent by Landlord to such holding over and shall not prevent
Landlord from exercising any of its remedies under this lease or applicable law
by reason of such holding over. Tenant shall be liable to Landlord for all
damage which Landlord suffers because of any holding over by Tenant, and Tenant
shall indemnify Landlord against all claims made by any other tenant or
prospective tenant against Landlord resulting from delay by Landlord in
delivering possession of the Premises to such other tenant or prospective
tenant.

        Section 20.02.
        --------------

                (a)  Tenant shall remove, at Tenant's expense, all of its
furniture, furnishings, personal property, and movable trade fixtures by the
Expiration Date, and shall promptly repair all damage done to the Premises or
the Building by such removal. Any items not so removed at the later of the
Expiration Date or the expiration of any period during which Tenant holds over
in the possession of the Premises as described in Section 20.01, shall be deemed
abandoned and shall thereupon become the property of Landlord.

                (b)  Except as provided in Section 20.02(a) and Section 20.01,
Tenant shall not remove any alteration made by Tenant or any of the leasehold
improvements in the Premises at the expiration of the Term without Landlord's
consent.

                                  ARTICLE 21

                             ESTOPPEL CERTIFICATES

     Tenant agrees to furnish no later than fifteen (15) days after a request
therefor by Landlord, any ground lessor, or the holder of any deed of trust or
mortgage covering the Building, the Land, or any interest of Landlord therein or
any purchaser of Landlord's interest, a certificate signed by Tenant certifying
(to the extent same is true) that this lease is in full force and effect and
unmodified; that the Term has commenced and the full Rental is then accruing
hereunder; that Tenant has accepted possession of the Premises and that any
improvements required by the terms of this lease to be made by Landlord have
been completed to the satisfaction of Tenant; that no Rental under this lease
has been paid more than thirty (30) days in advance of its due date; that the
address for notices to be sent to Tenant is as set forth in this lease (or has
been changed by notice duly given and is as set forth in the certificate); that
Tenant, as of the date of such certificate, has no knowledge of any charge,
lien, or claim of offset under this lease or otherwise against Rentals or other
charges due or to become due hereunder; that

                                     -32-
<PAGE>

Tenant has no knowledge of any default by Landlord then existing under this
lease; and such other matters as may be reasonably requested by Landlord or any
such ground lessor, holder of such deed of trust or mortgage or purchaser. If
Tenant is unable to so certify as to one or more of the foregoing items, Tenant
shall specify its reason therefor in writing. Any such certificate may be relied
upon by any prospective purchaser, ground lessor, mortgagee, or any beneficiary
under any deed of trust on the Building or the Land or any part thereof.
Landlord agrees to furnish periodically, when reasonably requested in writing by
Tenant, certificates signed by Landlord containing substantially the same
information as described above.

                                  ARTICLE 22

                                 SUBORDINATION

        Section 22.01.  Landlord warrants and represents that there is no deed
        --------------
of trust or mortgage in existence as of the date hereof covering or burdening
the Building and/or the Land. This lease shall be subject and subordinate to any
future first deeds of trust, first mortgages or other first security instruments
(collectively, "Superior Instruments") which may from time to time during the
Term cover the Building and/or the Land, or any interest of Landlord therein,
and to any advances made on the security thereof, and to any refinancings,
increases, renewals, modifications, consolidations, replacements, and extensions
of any such future Superior Instruments, provided that the holder of any such
Superior Instrument has executed, acknowledged and delivered a non-disturbance
agreement whereby such holder agrees not to diminish or interfere with Tenant's
possession of the Premises nor to disturb Tenant's occupancy of the Premises
except in accordance with Article 23 hereof. Upon execution and delivery of such
non-disturbance agreement, this Section 22.01 shall be self-operative and no
further instrument shall be required to effect such subordination of this lease.
Upon demand, however, Tenant shall execute, acknowledge, and deliver to Landlord
any further instruments and certificates evidencing such subordination as
Landlord or the holder of any Superior Instrument may reasonably request, and
Tenant hereby irrevocably appoints Landlord as Tenant's agent and attorney-in-
fact, for the purpose of executing, acknowledging, and delivering any such
instruments and certificates.

        Section 22.02.   Notwithstanding the generality or the foregoing
        --------------
provisions of Section 22.01 hereof, any holder of a Superior Instrument shall
have the right, unilaterally, at any time, to subordinate fully or partially any
such Superior Instrument to this lease. Upon request, Tenant shall execute an
instrument confirming any such full or partial subordination by any holder of a
Superior Instrument. At any time, before or after the institution of any
proceedings for the foreclosure of any Superior Instrument, or sale of the
Building and/or under any Superior Instrument, or upon the termination of any
ground lease, Tenant shall attorn to such purchaser upon any such sale or the
grantee under any deed in lieu of such foreclosure or to any ground lessor in
the event of a termination of a ground lease, as the case may be, and shall
recognize such ground purchaser, grantee or ground lessor, as the case may be,
as Landlord under this lease. Tenant hereby waives the right, if any, to elect
to terminate this lease or to surrender possession of the Premises in the event
of the judicial or non-judicial foreclosure of any deed of trust, mortgage, or
security agreement (or any transfer in lieu thereof) or termination of a ground
lease, subject to Tenant's right to terminate this lease under any provision of
any other Article

                                     -33-
<PAGE>

hereof upon the terms, conditions and contingencies therein provided. The
foregoing agreement of Tenant to attorn shall survive any such foreclosure sale,
trustee's sale, or conveyance in lieu thereof, or termination of a ground lease.
Tenant shall, upon demand at any time, before or after any such foreclosure
sale, trustee's sale, or conveyance in lieu thereof, or termination of a ground
lease, execute, acknowledge, and deliver to Landlord's mortgagee or any
successor thereof or any then owner of the Building or to the ground lessor (as
the case may be), any written instruments and certificates evidencing such
attornment as such mortgagee, successor, owner or ground lessor may reasonably
require, and Tenant hereby irrevocably appoints Landlord's mortgagee or ground
lessor (as the case may be) as Tenant's agent and attorney-in-fact for the
purpose of executing, acknowledging, and delivering any such instruments and
certificates.

        Section 22.03.   Should any ground lease be terminated, or any deed of
        --------------
trust, mortgage, or security instrument be foreclosed, the liability of the
ground lessor, mortgagee, trustee, or purchaser, as the case may be, as
"Landlord" hereunder, shall exist only with respect to the acts or omissions of
such person or entity occurring while it was the owner of the Land and/or
Building. Further, Tenant agrees that any such ground lessor, mortgagee,
trustee, or purchaser shall not be liable for (i) any Rental paid more than
thirty (30) days in advance of its due date (other than the one monthly
installment of Annual Rental paid in advance incident to the execution of this
lease); (ii) any amendment or modification of this lease without the prior
written approval of such ground lessor, mortgagee, trustee, or purchaser (but
only if Tenant had been notified in writing of the existence of the ground
lease, mortgage, deed of trust or sale, as the case may be, prior to the making
of such amendment or modification of this lease); or (iii) any default by or any
claim against any prior Landlord; provided that nothing in this Section is
intended or shall be construed to waive any right of Tenant to terminate this
lease by reason of a default by such prior Landlord in accordance with Section
25.05, or to cure any default by such prior Landlord and deduct the cost thereof
from Rental accruing hereunder in accordance with Section 25.05, either prior to
or after termination of such ground lease or foreclosure of such deed of trust,
mortgage or security instrument.

                                  ARTICLE 23

                             DEFAULT AND REMEDIES

        Section 23.01.   The occurrence of any one or more of the following
        --------------
events shall constitute an event of default under this lease: (a) if Tenant
shall fail to pay any Rental or other sums payable by Tenant hereunder as and
when such Rental or other sums become due and payable and such failure shall
continue for more than five (5) days after notice; (b) if Tenant shall fail to
perform or observe any covenant or obligation hereunder or any of the Rules and
Regulations and such failure shall continue for more than ten (10) days after
notice; or, if such failure cannot be corrected within such ten- (10) day
period, if Tenant does not commence to correct same within said ten- (10) day
period and thereafter diligently prosecute the correction of same to completion;
(c) if any petition is filed by or against Tenant under any section or chapter
of the present, or any future Federal Bankruptcy Code or under any similar law
or statute of the United States or any state thereof (which, in the case of an
involuntary proceeding, is not permanently discharged, dismissed, stayed, or
vacated, as the case may be, within sixty (60) days of its commencement), or if
any order for relief shall be entered against Tenant or any guarantor of
Tenant's obligations under this lease in proceedings filed under any section or
chapter of the

                                     -34-
<PAGE>

present or any future Federal Bankruptcy Code or under any similar law or
statute of the United States or any state thereof; (d) if Tenant becomes
insolvent or makes a transfer in fraud of creditors; (e) if Tenant makes an
assignment for the benefit of creditors; (f) if a receiver, custodian, or
trustee is appointed for Tenant or for any of the assets of Tenant, which
appointment is not vacated within sixty (60) days of the date of such
appointment or (g) if Tenant shall fail to pay to Landlord when due any Rental
becoming payable hereunder (without regard to any grace period otherwise allowed
by this Section 23.01) during any twelve- (12) month period during the Term
after Landlord has given Tenant written notice of failure to pay other
installments or amounts of Rental when due (prior to making of such payment by
Tenant) on at least two (2) prior separate occasions during such twelve- (12)
month period.

        Section 23.02.   If an event of default occurs, then at any time
        --------------
thereafter while Tenant remains in default, Landlord may do any one or more of
the following:

                (a)  Terminate this lease on three (3) days notice to Tenant, in
which event Tenant shall immediately surrender the Premises to Landlord. If
Tenant fails to do so, Landlord may, without notice and without prejudice to any
other remedy Landlord may have, enter upon and take possession of the Premises
and expel or remove Tenant and its effects without being liable to prosecution
or any claim for damages therefor; and Tenant shall indemnify Landlord for all
loss and damage which Landlord may suffer by reason of such termination, whether
through inability to relet the Premises or otherwise, including any loss of
Rental for the remainder of the Term. In the event of such termination, Landlord
shall exercise reasonable diligence and effort to relet the Premises for the
remainder of the Term.

                (b)  Enter upon and take possession of the Premises as Tenant's
agent, terminating this lease and without being liable to prosecution or any
claim for damages therefor, and Landlord may relet the Premises as Tenant's
agent and receive the Rental therefor, in which event Tenant shall pay to
Landlord on demand any and all costs of releasing, renovating, repairing, and
altering the Premises (including but not limited to advertising costs,
commissions, finders fees and other similar costs) for a new tenant or tenants
and any deficiency that may arise by reason of such reletting.

                (c)  Do whatever Tenant is obligated to do under this lease and
enter the Premises without, being liable to prosecution or any claim for damages
therefor to accomplish this purpose. Tenant shall reimburse Landlord immediately
upon demand for any expenses which Landlord incurs in thus effecting compliance
with this lease on Tenant's behalf, and Landlord shall not be liable for any
damages suffered by Tenant from such action, whether caused by the negligence of
Landlord or otherwise.

        Section 23.03.  No act or thing done by Landlord or its agents during
        --------------
the Term shall constitute an acceptance of an attempted surrender of the
Premises, and no agreement to accept a surrender of the Premises shall be valid
unless made in writing and signed by Landlord. No re-entry or taking possession
of the Premises by Landlord shall constitute an election by Landlord to
terminate this lease, unless a written notice of such intention is given to
Tenant. Notwithstanding any such reletting or re-entry or taking possession,
Landlord may at any time thereafter terminate this lease for a previous default.
Landlord's acceptance of Rental following an event of default hereunder shall
not be construed as a waiver of such event of default. No

                                     -35-
<PAGE>

waiver by Landlord of any breach of this lease shall constitute a waiver of any
other violation or breach of any of the terms hereof. Forbearance by Landlord to
enforce one or more of the remedies herein provided upon a breach hereof shall
not constitute a waiver of any other breach of the lease.

        Section 23.04.   No provision of this lease shall be deemed to have been
        --------------
waived by Landlord or Tenant unless such waiver is in writing and signed by such
party. Nor shall any custom or practice which may evolve between the parties in
the administration of the terms of this lease be construed to waive or lessen
Landlord's or Tenant's right to insist upon strict performance of the terms of
this lease. The rights granted to Landlord and Tenant in this lease shall be
cumulative of every other right or remedy which Landlord or Tenant may otherwise
have at law or in equity or by statute, and the exercise of one or more rights
or remedies shall not prejudice or impair the concurrent or subsequent exercise
of other rights or remedies.

                                  ARTICLE 24

                               WAIVER BY TENANT

     To the extent permitted by applicable law, Tenant waives for itself and all
claiming by, through, and under it, including creditors of all kinds, any right
and privilege which it or any of them may have under any present or future
constitution, statute, or rule of law to redeem the Premises or to have a
continuance of this lease for the Term after termination of Tenant's right of
occupancy by order or judgment of any court or by any legal process or writ,
under the terms of this lease, or after the termination of the Term as herein
provided.

                                  ARTICLE 25

                      ADDITIONAL COVENANTS AND AGREEMENTS

        Section 25.01.   The Land is covered by a Lease Agreement dated June 8,
        --------------
1982, between The Government of the United States, as "Lessor," and Landlord
herein, as "Lessee," as amended by a First Amendment to Lease Agreement dated
February 22, 1985, between such "Lessor" and "Lessee" (said Lease Agreement as
thus amended being herein called the "Ground Lease"). Landlord warrants and
represents that the Ground Lease is in full force and effect, that no default or
condition or circumstance which by the giving of notice and expiration of time
without cure would constitute a default by the "Lessee" under the terms of the
Ground Lease exists, and that Landlord as "Lessee" under the Ground Lease has
fully performed all obligations, duties and agreements of the "Lessee" which
have accrued or are required to be performed to date under the terms of the
Ground Lease.

        Section 25.02.   [INTENTIONALLY DELETED)
        --------------

        Section 25.03.   Landlord agrees to endeavor in good faith to obtain,
        --------------
and to deliver to Tenant, an executed, acknowledged nondisturbance agreement
from the "Lessor" under the Ground Lease, whereby such "Lessor" agrees not to
diminish or interfere with Tenant's possession of the Premises, for any reason
during the Term, unless and until this lease shall be terminated under the
provisions hereof for default by Tenant, provided, however, that if Landlord

                                     -36-
<PAGE>

is unable to obtain such nondisturbance agreement, this lease shall continue in
full force and effect, and the rights and obligations hereunder shall not be
affected.

        Section 25.04.   If a nondisturbance agreement from the "Lessor" under
        --------------
the Ground Lease as described in Section 25.03 is not obtained and furnished to
Tenant then (a) Landlord covenants and agrees that it will at all times during
the Term comply with and perform all obligations, duties and agreements of the
"Lessee" under and in connection with the Ground Lease and will maintain such
Ground Lease in full force and effect throughout the Term hereof, at Landlord's
cost and expense; (b) Landlord agrees to indemnify and save and hold Tenant
harmless from any loss, cost, expense, claim or liability whatsoever (including,
but without limitation, indirect and consequential damages, if any) which may be
suffered or incurred by Tenant as a result of any failure by Landlord to comply
with or perform its covenants and agreements under the provisions of clause (a)
of this Section 25.04; and (c) notwithstanding anything herein contained to the
contrary, Tenant shall have no obligation to attorn to the Ground Lessor in the
event the Ground Lease shall be terminated and the provisions of Section 22.02
of this Lease requiring Tenant to attorn to the Ground Lessor under the Ground
Lease and all references in Section 22.02 and 22.03 to the Ground Lessor and the
Ground Lease shall be deleted therefrom and shall be of no force or effect
whatsoever.

        Section 25.05.   If at any time or times Landlord shall be in default in
        --------------
the performance or observance of any of its covenants, agreements or
undertakings in this lease, and a court of competent jurisdiction has entered a
final judgment or decree not subject to appeal declaring Landlord to have
defaulted in the performance of its covenants, agreements or undertakings
hereunder, and if Landlord shall not cure or remedy such default as specified in
the final judgment or decree within thirty (30) days after the final judgment or
decree has been issued by the court and actually received by Landlord, or, if
such default as specified cannot reasonably be cured and remedied within thirty
(30) days, if Landlord shall not commence in good faith to cure and remedy such
default within thirty (30) days after the final judgment or decree has been
issued by the court and actually received by Landlord and continue with due
diligence until such default is cured and remedied, then, in addition to any
other rights or remedies that may be available to Tenant in law or equity:

                (a)  Tenant may terminate this lease by giving written notice of
termination to Landlord at any time thereafter and prior to the time when such
default is fully cured and remedied, in which event the Term of this lease will
end on the date specified in Tenant's notice of termination as if such date were
the date originally defined herein as the Expiration Date; or

                (b)  Tenant may, but shall not be obligated to, take such action
as in Tenant's good faith judgment is reasonably appropriate to cure and remedy
such default by Landlord, and Landlord shall, within ten (10) days after receipt
of demand therefor, pay to Tenant an amount equal to all reasonable costs and
expenses incurred by Tenant in so curing and remedying such default, failing
which Tenant shall be entitled to deduct and withhold the amount of such costs
and expenses, with interest thereon at the Prime Rate per annum from the date of
demand, from the next ensuing installments and payments of Rental becoming due
under this lease and shall not be in default hereunder for so doing. Tenant
shall have no liability for any action or omission taken or omitted in good
faith in connection with curing or remedying any default by Landlord pursuant to
this subsection 25.05(b); and Tenant's action in commencing to effect a

                                     -37-
<PAGE>

cure or remedy with respect to a default by Landlord pursuant to this subsection
25.05(b) shall not waive Tenant's continuing right, at its election, to
terminate this lease for such default pursuant to subsection 25.05(a) above at
any time before such default is fully cured and remedied.

        Section 25.06.  By Executive Order 11966 dated January 19, 1977,
        --------------
Landlord has been designated as a public international organization entitled to
enjoy the privileges, exemptions and immunities conferred by the International
Organizations Immunities Act (22 U.S.C. (S) 288). As authorized by 22 U.S.C.
288a(b), and as a material and essential consideration and inducement for Tenant
to enter into this lease, Landlord hereby expressly waives the immunity of
Landlord and its property and assets, wherever located, and by whomever held
(other than the INTELSAT Space Segment [the "Space Segment"] as described in
Article I(i) of that certain Agreement Relating to the International
Telecommunications Satellite Organization ["INTELSAT"] done at Washington, D.C.
August 420, 1971, and entered into force February 12, 1973), from suit and any
form of judicial process conferred Act or which by said International
Organizations Immunities Act or which might otherwise exist under international
law or otherwise, with respect to any claim, (a "Subject Claim") of Tenant or
its successors or assigns arising under or in connection with this lease or in
connection with any dispute hereunder or by virtue of any default by Landlord
under this lease or any failure or refusal by Landlord to perform or observe any
of its covenants, agreements, undertakings or duties hereunder; and in this
regard Landlord expressly agrees that any United States District Court in the
District of Columbia shall have jurisdiction to entertain suits for and hear and
render judgment on and with respect to any Subject Claim, that service upon
Landlord in any such suit may be effected by service upon the Director General
or acting Director General of Landlord (or their successors in office) in a
manner consistent with the Federal Rules of Civil Procedure. If Tenant after
using reasonable efforts is unable to effect service upon the Director General
or acting Director General (or their successors in office) as provided above,
Tenant may notify Landlord of such inability which notice shall contain a copy
of the complaint or other process or material sought to be served, and five (5)
days after such notice has been delivered to Landlord, Tenant may effect service
upon any officer or executive of Landlord or in any other manner provided in the
Federal Rules of Civil Procedure for effecting service upon a Corporation
organized under the laws of a state of the United States of America. Execution
or any other process provided for by law of the Federal Rules of Civil Procedure
may be levied and enforced upon and against any property or assets of Landlord,
wherever located, and by whomever held other than any part of the Space Segment,
for satisfaction of any final judgment against Landlord rendered in any suit on
or with respect to a Subject Claim.

                                  ARTICLE 26

                             VAN PARKING FACILITY

     Tenant shall have the right to have constructed a parking facility to allow
Tenant to park five (5) vans located adjacent to the ramp leading into the
Building parking garage in the area described in Exhibit H as hereinafter
provided.  Tenant shall submit to Landlord preliminary plans and specifications
for such facility for Landlord's approval, such approval not to be unreasonably
withheld.  If Landlord approves the preliminary plans and specifications, and
provided Tenant receives the approval of any necessary governmental authority,
Landlord shall

                                     -38-
<PAGE>

prepare final plans and specifications consistent with such approved preliminary
plans and specifications, and shall construct such additional parking facility
substantially in accordance with such final plans and specifications. Landlord
shall pay that part of the cost of constructing such additional parking facility
equal to the lesser of (i) 50% of such costs or (ii) Twenty-Five Thousand
Dollars ($25,000.00) and Tenant shall pay the remainder of such costs. During
the Term, Tenant shall maintain and repair the additional parking facility at
Tenant's sole cost and expense, provided, however, that Landlord shall be
responsible for all structural repairs which may be required.

                                  ARTICLE 27

                      ATTORNEYS' FEES AND LEGAL EXPENSES

     In any action or proceeding brought by either party against the other under
this lease, the prevailing party shall be entitled to recover from the other
party reasonable attorneys' fees, investigation costs, and other reasonable
legal expenses and court costs incurred by such party in such action or
proceeding.

                                  ARTICLE 28

                                    NOTICES

        Section 28.01.   Any notice or demand, consent, approval or disapproval,
        --------------
or statement (collectively called "Notices") required or permitted to be given
by the terms and provisions of this lease, or by any law or governmental
regulation, shall be in writing (unless otherwise specified herein) and unless
otherwise required by such law or regulation, shall be personally delivered or
sent by United States mail postage prepaid as registered or certified mail,
return receipt requested. Any Notice shall be addressed to Landlord or Tenant,
as applicable, at its address specified in the Basic Lease Information as said
address may be changed from time to time as hereinafter provided. By giving the
other party at least ten (10) days' prior written notice, either party may, by
Notice given as above provided, designate a different address or addresses for
Notices.

        Section 28.02.   Any Notice shall be deemed given as of the date of
        --------------
delivery as indicated by affidavit in case of personal delivery or by the return
receipt in the case of mailing; and in the event of failure to deliver by reason
of changed address of which no Notice was given or refusal to accept delivery,
as of the date of such failure as indicated by affidavit or on the return
receipt or by notice of postal service, as the case may be.

                                  ARTICLE 29

                                    PARKING

        Section 29.01.   Landlord shall provide or require that any garage
        --------------
operator shall offer to Tenant up to the sum of (i) fifty (50) plus (ii) one (1)
for each additional 1,300 square feet of Rentable Area of the Premises above
73,153 square feet, monthly parking contracts to park an automobile ("Parking
Rights") in the Building garage. Parking Rights shall be on a self-park or

                                     -39-
<PAGE>

attendant parking basis, as determined by the garage operator (whether Landlord
or a third party).

        Section 29.02.   The monthly parking rate for Parking Rights shall be
        --------------
the prevailing rate charged from time to time by the garage operator for similar
monthly parking contracts. Except as otherwise provided herein, contracts for
the Parking Rights shall be with the garage operator and shall contain the same
terms as are usually contained in contracts with other customers of the garage
operator.

        Section 29.03.   If Tenant does not contract for the maximum number of
        --------------
Parking Rights so allocated to it within ninety (90) days after the Commencement
Date, then Tenant's rights to the unused Parking Rights shall expire. However,
in the event there are Parking Rights available not needed by Landlord or any
tenant in the Building, Tenant shall have the right to contract for such Rights
until such time as Landlord requests that Tenant give up such Rights to permit
their use by Landlord or another tenant of the Building. It is, however,
expressly agreed that if the garage operator is Landlord or Landlord's
Affiliate, the monthly parking rate for Parking Rights shall not exceed the
prevailing monthly parking rates in the general area of the Building for
comparable parking facilities; and the terms of the contracts for the Parking
Rights shall be reasonable and not more onerous from the customer's standpoint
than terms customarily contained in monthly parking contracts of other garage
operators in the area of the Building with respect to comparable parking
facilities.

        Section 29.04.   If all or any portion of the parking facilities in the
        --------------
Building shall be damaged or rendered unusable by fire or other casualty or any
taking pursuant to eminent domain proceeding (or deed in lieu, thereof), and as
a result thereof Landlord or the garage operator is unable to make available to
Tenant the parking provided for herein, then the number of cars which Tenant
shall be entitled to park hereunder shall be proportionately reduced so that the
number of cars which Tenant may park in the parking garage after the casualty or
condemnation in question shall bear the same ratio to the total number of cars
which can be parked in the parking garage at such time as the number of cars
Tenant had the right to park in the parking garage prior cars to such casualty
or condemnation bore to the aggregate number of cars which could be parked
therein at that time.

                                  ARTICLE 30

                 ROOF ANTENNA AND SATELLITE DISH INSTALLATION

        Section 30.01.   Tenant shall have the right to install at its sole cost
        --------------
and expense microwave and satellite dish systems (the "Communication Systems")
on the roof of the Building and/or the Land, in accordance with the
specifications (the "Communication Systems Specifications") attached hereto as
Exhibit K and at locations shown on Exhibit K, subject to obtaining all
necessary governmental approvals and permits related thereto. In the event that
the Tenant obtains all necessary governmental approvals and permits for the
installation of the Communication Systems, Tenant may then proceed to install
the Communication Systems, at Tenant's expense, in strict compliance with the
specifications previously provided to Landlord and all applicable governmental
requirements. Tenant acknowledges that it has received a copy of the letter from
Landlord to Tenant regarding U.S. Department of State approval of the

                                     -40-
<PAGE>

Communication Systems, which is attached hereto as Exhibit I. The parties agree
that Landlord shall not make any use whatsoever of the Communications Systems of
Tenant.

        Section 30.02.   During the Term, Tenant, at its sole cost and expense
        --------------
shall maintain and repair the Communication Systems, and, if necessary, shall
install shielding material to protect Landlord's antennas and other technical
facilities now or hereafter installed by Landlord. The Communication Systems
shall be covered by Tenant's All-Risk insurance in accordance with Section
15.01(a). Tenant hereby agrees to indemnify and hold Landlord harmless from and
against any loss or injury of any kind or nature whatsoever arising out of the
installation or operation of the Communication Systems, and any damage to the
Building or the Land caused by such Communication Systems or as a result of such
Communication Systems or any casualty thereto shall be repaired by Tenant at
Tenant's expense.

        Section 30.03.   Landlord shall not install or permit the installation
        --------------
of any other antenna on the INTELSAT Headquarters Building and/or the Land, or
any building thereon, that would interfere with Tenant's reception or broadcast
capabilities under the Communication System Specifications.

                                  ARTICLE 31

                              MEMORANDUM OF LEASE

        Section 31.01.   Landlord shall, at the request of Tenant, execute,
        --------------
acknowledge and deliver to Tenant a memorandum of this lease (a "Lease
Memorandum") in recordable form setting forth the date of this lease, the names
of the parties hereto, the Commencement Date and the Expiration Date and
describing the Premises, Tenant's rights to renew this lease and the Land. Said
Lease Memorandum shall not in any circumstances be deemed to modify or to change
any of the provisions of this lease. Tenant may elect, at its sole expense, to
record said Lease Memorandum.

        Section 31.02.   In event that Landlord executes said Lease Memorandum,
        --------------
Tenant shall after the expiration or termination of the Term, at the request of
Landlord, execute, acknowledge and deliver to Landlord a memorandum in
recordable form evidencing the expiration or termination of this lease. Landlord
may elect, at its sole expense, to record said memorandum.

                                  ARTICLE 32

                                RENEWAL OPTIONS

        Section 32.01.   Tenant shall have and is hereby granted one (1) option
        --------------
to renew or extend the Term for an additional period of five (5) years (the
"Renewal Period"). Subject to the provisions of Section 32.03, the renewal
option shall be exercisable by Tenant by giving written notice of the exercise
of such renewal option to Landlord at least one (1) year prior to the expiration
of the initial Term. In the event that Tenant exercises the option to renew this
lease in accordance with the provisions hereof, then the Term shall be extended
accordingly. Except as otherwise expressly provided herein, the Renewal Period
shall be upon the same terms, covenants and conditions as set forth herein with
respect to the immediately preceding portion of

                                     -41-
<PAGE>

the Term. All references in this lease to the Term shall be construed to mean
the initial Term and the Renewal Period, (and if applicable the Contingent,
Renewal Periods as hereinafter defined) unless the context clearly indicates
that another meaning is intended. For purposes of this lease, no distinction is
made between the terms "extend" and "renew," or any variations thereof.

        Section 32.02.
        --------------

                (a)  If Tenant notifies Landlord in writing on or before the
date which is thirty (30) days after the date of execution of this lease that
Tenant elects to exercise its renewal option, the Annual Rental during the
Renewal Period shall equal [redacted text] multiplied by the Rentable Area of
the Premises and there shall be no change in the amount of the Basic Costs Base
Amount.

                (b)  If Tenant notifies Landlord in writing after the date which
is thirty (30) days after the date of execution of this lease but before the
date that is one (1) year prior to the expiration of the initial Term, that
Tenant elects to exercise its renewal option, the Annual Rental for the Premises
payable pursuant to Section 5.01 for each Lease Year during the Renewal Period
shall equal the greater of (i) the sum of (A) [redacted text] multiplied by the
Rentable Area of the Premises plus (B) an amount per square foot of Rentable
Area equal to fifty percent (50%) of the annualized amount of Tenant's
Proportionate Share of Basic Costs Excess for the Fiscal Year ending during the
Lease Year immediately preceding the Renewal Period divided by the number of
square feet of Rentable Area in the Premises during such preceding Lease Year,
or (ii) ninety-five percent (95%) of the Fair Market Value Rate (as defined
below) of the Premises as of the commencement of the Renewal Period multiplied
by the Rentable Area of the Premises, increased during the second and each
succeeding Lease Year of the Renewal Period by the Market Escalation Factor (as
defined below). In the event Annual Rental during the Renewal Period is
determined pursuant to this Section 32.02(b), the Basic Costs Base Amount for
purposes of calculating Basic Costs Excess shall equal the Basic Costs for the
Fiscal Year ending during the Lease Year immediately preceding the Renewal
Period. For purposes of the preceding sentence, and for purposes of all other
determinations of the Fair Market Value Rate pursuant to this lease, the
applicable percentage of the "Fair Market Value Rate" shall be increased each
Lease Year by whatever periodic adjustment or factor ("Market Escalation
Factor"), CPI or otherwise, that would be agreed upon between a landlord and a
tenant entering into a new lease in a comparable building, assuming the same
assumptions set forth in 32.04. The Market Escalation Factor shall be determined
in the same manner and at the same time as the Fair Market Value Rate as
provided in Sections 32.02(b) and 32.04; provided, however, that the Market
Escalation Factor shall not be less than thirty percent (30%) of the CPI
adjustment (or other similar adjustment factor that may be applicable).

                (c)  If Tenant exercises its renewal option after the date which
is thirty (30) days after the date of execution of this lease, within sixty (60)
days after Landlord has received Tenant's notice of election to extend the Term,
Landlord shall send to Tenant a written notice specifying the Fair Market Value
Rate and Market Escalation Factor as determined by Landlord in accordance with
Section 32.04, provided, however, that in no event shall Landlord be required to
specify its determination of the Fair Market Value Rate and Market Escalation
Factor prior to the date which is one (1) year before the expiration of the
Term. Within fifteen (15) days after receipt of such notice from Landlord,
Tenant shall send Landlord a written notice of Tenant's acceptance or challenge
of Landlord's determination of such Fair Market Value Rate and Market

                                     -42-
<PAGE>

Escalation Factor, provided, however, that in the event that Tenant fails to
respond within such fifteen- (15) day period, Tenant shall be deemed to have
accepted Landlord's determination of the Fair Market Value Rate and Market
Escalation Factor. In the event that Tenant challenges Landlord's determination
of the Fair Market Value Rate and Market Escalation Factor and Landlord and
Tenant are not able to agree on such Fair Market Value Rate and Market
Escalation Factor within fifteen (15) days (the "Negotiation Period") after
Tenant notified Landlord of Tenant's initial rejection of Landlord's
determination of such Fair Market Value Rate and Market Escalation Factor, then
Landlord and Tenant shall each, within fifteen (15) days after the expiration of
the Negotiation Period, select an appraiser, each of whom shall be a District of
Columbia-licensed real estate broker or a MAI-certified real estate appraiser
with ten years experience in the District of Columbia office market, who shall
determine the Fair Market Value Rate and Market Escalation Factor in accordance
with Section 32.04. The appraisers shall be instructed to complete the appraisal
procedure and to submit their written determinations to Landlord and Tenant
within thirty (30) days after their meeting. In the event that the determination
of the Fair Market Value Rate or Market Escalation Factor, respectively,
submitted by Landlord's appraiser is less than or equal to one hundred ten
percent (110%) of the determination of the Fair Market Value Rate or Market
Escalation Factor, as applicable, submitted by Tenant's appraiser, said Fair
Market Value Rate or Market Escalation Factor shall be the average of such
determinations. If the determination of the Fair Market Value Rate or Market
Escalation Factor, respectively, submitted by Landlord's appraiser is greater
than one hundred ten percent (110%) of the determination of the Fair Market
Value Rate or Market Escalation Factor, as applicable, submitted by Tenant's
appraiser, the appraisers shall, within ten (20) days, appoint a third appraiser
with similar qualifications to make such determination of Fair Market Value Rate
or Market Escalation Factor (or both, as applicable) in accordance with the
foregoing limitations. In the event that the two appraisers cannot agree as to
the selection of the third appraiser within fifteen (15) days after Landlord and
Tenant are notified of the determination of the appraisers, either party may
request that the President of the Washington Board of Realtors appoint the third
appraiser. The third appraiser shall be instructed to complete the appraisal
procedure and to submit a written determination of the Fair Market Value Rate or
Market Escalation Factor (or both, as applicable) to Landlord and Tenant within
thirty (30) days after such appraiser's appointment. The determination which is
neither the highest nor the lowest of the three determinations of such Fair
Market Value Rate or Market Escalation Factor (or both, as applicable) shall be
binding upon Landlord and Tenant as the Fair Market Value Rate or Market
Escalation Factor (or both, as applicable). Landlord and Tenant shall each bear
the costs of their respective appraisers. The expenses of the third appraiser
shall be borne one-half (1/2) by Landlord and one-half (1/2) by Tenant.

        Section 32.03.  The renewal option referred to in Section 32.01 above
        --------------
(and the renewal options for the Contingent Renewal Periods described below) may
not be exercised by Tenant if, at the time of exercising such option(s), (i)
this lease shall not be in full force and effect or (ii) an event of default (as
defined in Section 23.01) shall have occurred and shall be continuing. If Tenant
shall fail to exercise the renewal option during the time or in the manner
provided in Section 32.01 for the exercise thereof and at a time when Tenant is
not prohibited from exercising such option under the provisions of this Section
32.03, then, and in such event, such renewal option shall be absolutely void and
of no force and effect.

                                     -43-
<PAGE>

        Section 32.04.   For purposes of this lease, the term "Fair Market Value
        --------------
Rate" means the fair market rental rate per square foot of Rentable Area of the
Premises that would be agreed upon between a landlord and a tenant entering into
a new lease in a comparable building of comparable age, assuming the following:
(A) the landlord and tenant are typically motivated; (B) the landlord and tenant
are well informed and well advised and each is acting in what it considers its
own best interest; (C) the rental is unaffected by concessions, special
financing amounts and/or terms, or unusual services, fees, costs or credits in
connection with the leasing transaction; (D) the Premises are fit for immediate
occupancy and use "as is" and no work is required to be done by landlord and no
work has been carried out thereon by any prior tenant, its subtenant, or their
predecessors in interest during the term which has diminished the rental value
of the Premises; (E) in the event the Premises have been destroyed or damaged by
fire or other casualty, they have been fully restored; (F) the Premises are to
be let with vacant possession and subject to the provisions of this lease for a
five-year term (taking into account the provisions of this lease, including
without limitation Article 6 and Section 8.01 hereof); and (C) market rents then
being charged for comparable space in other similar office buildings in
comparable locations in Washington, D.C.; and (H) the rental determined as the
fair market rental rate as of the commencement of the term of the subject lease
will be subject to being increased during the second and each succeeding year of
the five- (5) year term of the lease by application of the Market Escalation
Factor described below. Likewise, for purposes of this lease, the term "Market
Escalation Factor" shall mean whatever periodic adjustment or factor (Consumer
Price Index ["CPI"] or otherwise) that would be agreed upon by a landlord and a
tenant entering into a new lease in a comparable building of comparable age,
assuming the same assumptions set forth in clauses (A), (B), (C), (D), (E), (F)
and (G) of the first sentence of this Section; provided, however, that the
Market Escalation Factor shall not be less than thirty percent (30%) of the CPI
adjustment (or other similar adjustment factor that may be applicable).

        Section 32.05.
        --------------

                (a)  Provided Tenant has exercise its renewal option and is then
occupying at least seventy-five percent (75%) of the Premises, Landlord shall
notify Tenant on or before the expiration of the twelfth (12th) Lease Year of
the Renewal Period whether Landlord will grant to Tenant three (3) additional
successive options to renew or extend the Term for additional periods of five
(5) years each (the "Contingent Renewal Periods"). In the event Landlord's
notice states that no additional renewal periods will be available, then the
Annual Rental during the last seven and one-half months of the Renewal Period
shall be abated. If Landlord's notice states that Tenant may elect to extend the
Term for the Contingent Renewal Periods, there shall be no such Rental
abatement; and subject to the provisions of Section 32.03, each such renewal
option shall be exercisable by Tenant by giving written notice of the exercise
of such renewal option to Landlord at least one (1) year prior to the expiration
of the Renewal Period in the case of the first such renewal option, and in the
case of the second and third such renewal options, before the expiration of the
immediately preceding Contingent Renewal Period. Except as otherwise expressly
provided herein, each Contingent Renewal Period shall be upon the same terms,
covenants and conditions as set forth herein with respect to the immediately
preceding portion of the Term.

                (b)  The Annual Rental for the Premises payable pursuant to
Section 5.01 for each Lease Year during the first Contingent Renewal Period
shall be equal to the total of (i) the

                                     -44-
<PAGE>

Annual Rental payable by Tenant during the Lease Year immediately preceding such
Contingent Renewal Period divided by the number of square feet of Rentable Area
in the Premises during such preceding Lease Year, multiplied by the number of
square feet of Rentable Area in the Premises during the applicable Lease Year of
the first Contingent Renewal Period, plus (ii) [redacted text] multiplied by the
number of square feet of Rentable Area in the Premises during the applicable
Lease Year of the first Contingent Renewal Period. The Annual Rental for each
Lease Year during the second Contingent Renewal Period shall equal the greater
of (i) the sum of (A) the Annual Rental payable by Tenant during the Lease Year
immediately preceding such second Contingent Renewal Period plus (B) fifty
percent of Tenant's Proportionate Share of Basic Costs Excess payable by Tenant
during the Lease Year immediately preceding such second Contingent Renewal
Period, divided by the number of square feet of Rentable Area in the Premises
during such preceding Lease Year, multiplied by the number of square feet of
Rentable Area in the Premises during the applicable Lease Year of the second
Contingent Renewal Period, or (ii) ninety-five percent (95%) of the Fair Market
Value Rate of the Premises as of the commencement of the second Contingent
Renewal Period multiplied by the Rentable Area of the Premises; increased during
the second and each succeeding Lease Year of the second Contingent Renewal
Period by the Market Escalation Factor. The Annual Rental during the third
Contingent Renewal Period shall equal the greater of (i) the sum of (A) the
Annual Rental Payable by Tenant during the Lease Year immediately preceding such
third Contingent Renewal Period plus (B) fifty percent (50%) of Tenant's
Proportionate Share of Basic Costs Excess payable by Tenant during the Lease
Year immediately preceding such third Contingent Renewal Period, divided by the
number of square feet of Rentable Area in the Premises during such preceding
Lease Year, multiplied by the number of square feet of Rentable Area in the
Premises during the applicable Lease Year of the Third Contingent Renewal
Period, or (ii) ninety-five percent (95%) of the Fair Market Value Rate of the
Premises as of the commencement of the third Contingent Renewal Period
multiplied by the, Rentable Area of the Premises, increased during the second
and each succeeding Lease Year of the third Contingent Renewal Period by the
Market Escalation Factor. The Basic Cost Base Amount for purposes of calculating
Basic Costs Excess for the First Contingent Renewal Period shall be equal to the
Basic Cost Base Amount for the initial Renewal Period. The Basic Costs Base
Amount for purposes of calculating Basic Costs Excess during the second or third
Contingent Renewal Period shall be equal to the Basic Costs for the Fiscal year
ending during the Lease Year immediately preceding such particular Contingent
Renewal Period.

                (c)  In the case of the second and third Contingent Renewal
Periods, Landlord shall within sixty (60) days after Landlord has received
Tenant's notice of election to extend the Term, send to Tenant a written notice
specifying the Fair Market Value Rate as determined in accordance with Section
32.04, provided, however, that in no event shall Landlord be required to specify
its determination of the Fair Market Value Rate prior to the date which is one
(1) year before the expiration of the first or second Contingent Renewal Period,
as the case may be. Except where the context indicates otherwise, the provisions
of Sections 32.02, 32.03 and 32.04 shall apply equally to this Section 32.05.

                                     -45-
<PAGE>

                                  ARTICLE 33

                               EXPANSION OPTION

        Section 33.01.  Subject to the terms and conditions hereinafter set
        --------------
forth and provided that the lease is in full force and effect and no event of
default shall have occurred which shall be continuing, Tenant shall have the
option to lease additional space in the Building (the "Expansion Space") as
follows. Tenant shall have the option (the "Expansion Option") to lease the
space on level 6 of Pod P described in Exhibit J hereto as hereinafter provided.
The Expansion Option shall be exercisable by Tenant upon notice to Landlord
given within six (6) months after the date of execution of this lease. If Tenant
so exercises its Expansion Option as herein provided, such space shall be added
to and constitute a part of the premises, and except as expressly otherwise
hereinafter provided, subject to all the terms and conditions of this lease. If
Tenant delivers to Landlord the drawings, plans, specifications, and other
detailed information which Tenant is required to submit to Landlord in
accordance with Article 2.02 of Exhibit C, if applicable, containing all
information required by Landlord to construct the Base Building Work for the
Expansion Space, the Commencement Date, Expiration Date and free rent period as
to the Expansion Space shall be the same as those for the initial Premises. If
such drawings, plans, specifications, and other detailed information for the
Expansion Space are not delivered by the respective dates specified in Article
2.02 of Exhibit C, if applicable, (i) the delivery date by Landlord of the
Expansion Space with the Base Building Work substantially completed shall have
no effect upon the determination of the Commencement Date for the initial
Premises; (ii) the Commencement Date and commencement of the seven-month free-
rent period for the Expansion Space shall be the earlier of (A) seven and one-
half (7 1/2) months after the date on which Landlord delivers the Expansion
Space to Tenant with the Base Building Work substantially completed, (B) the
date of Tenant's occupancy of the Expansion Space for the conduct of its normal
business operations, or (C) fifteen (15) days after (1) Tenant Build-out for the
Expansion Space is substantially completed, and (2) the Communication Systems
have been installed on the Building and Land, so as to permit Tenant to occupy
the Expansion Space (and the initial Premises) and conduct its normal business
operations therein, it being stipulated that Tenant agrees, subject to delay by
force majeure as defined in Section 2.01(b), to exercise reasonable diligence to
complete and install such Tenant Build-out and Communication Systems after
Tenant is afforded access to the Land, Building, Premises and Expansion Space
for such purpose; (iii) delays by Tenant as specified in Articles 6 and 7 of
Exhibit C with respect to the Expansion Space shall operate to accelerate
Tenant's obligation to pay rental for the Expansion Space; and (iv) The
Expiration Date for the Expansion Space shall coincide with the Expiration Date
of the initial Premises.

        Section 33.02.   Landlord shall construct in the Expansion Space the
        --------------
Base Building Work described in Exhibit C-1 and Landlord shall have no
obligation to make any other alterations, decorations, additions or improvements
in or to the Expansion Space.

                                  ARTICLE 34

                                 MISCELLANEOUS

        Section 34.01.   [INTENTIONALLY DELETED]
        --------------

                                     -46-
<PAGE>

        Section 34.02.   Landlord recognizes Shannon & Luchs Company (the
        --------------
"Broker") and Julien J. Studley Co., Inc. (the "Co-operating Broker") as the
sole brokers procuring this lease. Landlord shall pay the Broker a commission
therefor pursuant to a separate agreement between the Broker and Landlord, and
the Broker shall pay a portion of such commission to the Co-operating Broker.
Except for the Broker and the Co-operating Broker, Landlord and Tenant each
represent and warrant that it has not entered into any agreement with, nor
otherwise had any dealings with, any other broker or agent in connection with
the negotiation or execution of this lease which could form the basis of any
claim by any such broker or agent for a brokerage fee or commission, finder's
fee, or any other compensation of any kind or nature in connection herewith, and
Landlord and Tenant each agree to indemnify and hold the other harmless from any
costs (including, but not limited to, court costs, investigation costs, and
attorneys' fees), expenses, or liability for commissions or other compensation
claimed by any broker or agent with respect to this lease which arise out of any
agreement or dealings, or alleged agreement or dealings, between such party and
any such agent or broker.

        Section 34.03.   As used herein, "business days" means Monday through
        --------------
Friday (except holidays); "normal business hours" means 8:00 a.m. to 6:00 p.m.
on business days; and "holidays" means those holidays other than Veterans Day
designated as national holidays by the government of the United States and the
Friday following Thanksgiving Day.

        Section 34.04.   Every agreement contained in this lease is, and shall
        --------------
be construed as, a separate and independent agreement. If any term of this lease
or the application thereof to any person or circumstances shall be invalid and
unenforceable, the remainder of this lease, or the application of such term to
persons or circumstances other than those as to which it is invalid or
unenforceable, shall not be affected.

        Section 34.05.   There shall be no merger of this lease or of the
        --------------
leasehold estate hereby created with the fee estate in the Premises or any part
thereof by reason of the fact that the same person may acquire or hold, directly
or indirectly, this lease or the leasehold estate hereby created or any interest
in this lease or in such leasehold estate as well as the fee estate in the
Premises or any interest in such fee estate. In the event of a voluntary or
other surrender of this lease, or a mutual cancellation hereof, Landlord may, at
its option, terminate all subleases, or treat such surrender or cancellation as
an assignment of such subleases.

        Section 34.06.   [Intentionally Deleted].
        --------------

        Section 34.07.   Whenever a period of time is herein prescribed for
        --------------
action to be taken by Landlord, Landlord shall not be liable or responsible for,
and there shall be excluded from the computation for any such period of time,
any delays due to "force majeure" as such term is defined in Section 2.01(b)
other than Landlord's obligations with respect to insurance as provided in
Article 15 or Landlord's obligation to make timely payment of all amounts
becoming due from Landlord to Tenant hereunder. Likewise, whenever a period of
time is herein prescribed for action to be taken by Tenant, Tenant shall not be
liable or responsible for, and there shall be excluded from the computation for
any such period of time, any delays due to "force majeure" as such term is
defined in Section 2.01(b), other than Tenant's obligations with respect to
insurance as provided in Article 15, Tenant's obligation to timely pay Rental,
and Tenant's obligation to comply with all time requirements specified in
Exhibit C. In addition, no

                                     -47-
<PAGE>

force majeure circumstance shall operate to (i) extend the seven and one-half
(7 1/2) month period contained in clause (i) of Section 2.01(a), or (ii) extend
the date April 1, 1989, or the date April 1, 1990, contained in Section 3.01 or
(iii) extend the ten- (10) day period contained in Section 8.04.

        Section 34.08.   The article headings contained in this lease are for
        --------------
convenience only and shall not enlarge or limit the scope or meaning of the
various and several articles hereof.  Words of any gender used in this lease
shall include any other gender, and words in the singular number shall be held
to include the plural, unless the context otherwise requires.

        Section 34.09.   If there be more than one Tenant, the obligations
        --------------
hereunder imposed upon Tenant shall be joint and several, and all agreements and
covenants herein contained shall be binding upon the respective heirs, personal
representatives, successors, and, to the extent permitted under this lease,
assigns of the parties hereto.

        Section 34.10.   Neither Landlord nor Landlord's agents or brokers have
        --------------
made any representations or promises with respect to the Premises or the
Building except as herein expressly set forth and all reliance with respect to
any representations or promises is based solely on those contained herein. No
rights, easements, or licenses are acquired by Tenant under this lease by
implication or otherwise except as expressly set forth in this lease.

        Section 34.11.   This lease sets forth the entire agreement between the
        --------------
parties and cancels all prior negotiations, arrangements, brochures, agreements,
and understandings, if any, between Landlord and Tenant regarding the subject
matter of this lease. No amendment or modification of this lease shall be
binding or valid unless expressed in a writing executed by both parties hereto.

        Section 34.12.   The submission of this lease to Tenant shall not be
        --------------
construed as an offer, nor shall Tenant have any rights with respect thereto
unless Landlord executes a copy of this lease and delivers the same to Tenant.

        Section 34.13.   Each of the persons executing this lease on behalf of
        --------------
Tenant represents and warrants that Tenant has complied with all applicable
laws, rules, and governmental regulations relative to its right to do business
in the District of Columbia, that such entity has the full right and authority
to enter into this lease, and that all persons signing on behalf of the Tenant
were authorized to do so by any and all necessary or appropriate corporate or
partnership actions.

        Section 34.14.   Each of the persons executing this lease on behalf of
        --------------
Landlord and/or the general partner of Landlord represents and warrants that
Landlord has complied with all applicable laws, rules and governmental
regulations relative to its right to do business in the District of Columbia,
that such entity has the full right and authority to enter into this lease, and
that all persons signing on behalf of Landlord were authorized to do so by any
and all necessary or appropriate actions.

        Section 34.15. If, in connection with obtaining debt or equity financing
        --------------
for the Building (including a sale/ leaseback) any lender, investor or ground
lessor shall request reasonable modifications to this lease as a condition to
such financing, Tenant will consent

                                     -48-
<PAGE>

thereto if in Tenant's sole good faith determination such modifications do not
increase the obligations of Tenant hereunder or adversely affect the leasehold
interest hereby created, Tenant's use and enjoyment of the Premises or any other
right of Tenant granted hereunder.

        Section 34.16.   This lease shall be governed by and construed under the
        --------------
laws of the District of Columbia. Any action brought to enforce or interpret
this lease shall be brought in the court of appropriate jurisdiction in the
District of Columbia. Should any provision of this lease require judicial
interpretation, it is agreed that the court interpreting or considering same
shall not apply the presumption that the terms hereof shall be more strictly
construed against a party by reason of the rule or conclusion that a document
should be construed more strictly against the party who itself or though its
agent prepared the same, it being agreed that all parties hereto have
participated in the preparation of this lease and that legal counsel was
consulted by each party hereto before the execution of this lease.

        Section 34.17.   Tenant shall not, without the prior written consent of
        --------------
Landlord, use the name of the Building for any purpose other than as the address
of the business to be conducted by Tenant in the Premises, nor shall Tenant use
the name of the Building as Tenant's business address after Tenant vacates the
Premises, nor shall Tenant do or permit the doing of anything in connection with
Tenant's business or advertising which in the reasonable judgment of Landlord
may reflect unfavorably on Landlord or the Building or confuse or mislead the
public as to any apparent connection or relationship between Landlord, the
Building, and the Tenant.

        Section 34.18.   Any elimination or shutting off of light, air, or view
        --------------
by any structure which may be erected on lands adjacent to the Building and not
located on the Land shall in no way affect this lease or impose any liability on
Landlord.

        Section 34.19.   The exhibits referred to in the Basic Lease Information
        --------------
are by this reference incorporated fully herein. The term "this lease" shall be
considered to include all such exhibits.

        Section 34.20.   As provided in Section 1.01, during the Term, Landlord
        --------------
shall allow Tenant and Tenant's officers, employees and invitees reasonable
access and use of the cafeteria in the INTELSAT Headquarters Building, subject
to any and all reasonable Rules and Regulations pertaining thereto that Landlord
may from time to time adopt.

        Section 34.21.   An electronic building security system of a similar
        --------------
nature and quality as the electronic building security system now operating in
the Phase I building on the Land shall be provided by Landlord at Landlord's
sole cost and expense to limit access to the Building. It is understood and
agreed that Landlord shall not be responsible for the quality of such system, or
for any damage or injury to Tenant, its employees, invitees or others due to any
failure of such system.

        Section 34.22.   Landlord warrants and represents to Tenant that the
        --------------
aggregate amount of floor space of the Premises plus the Expansion Space,
together with the amount of all other floor space in the INTELSAT Headquarters
Building currently leased to persons or entities other than Priority Subtenants
(as such term is defined in the Ground Lease) does not equal or exceed twenty
percent (20%) of the total floor space above grade of the INTELSAT Headquarters

                                     -49-
<PAGE>

Building.  Landlord understands that Tenant is relying on this representation in
not seeking approval of the "Planning Commission" as to this lease under the
terms of Article 7(l)(g) of the Ground Lease.

        Section 34.23.   Under the provisions of the Ground Lease, in the event
        --------------
of termination thereof, the "Lessor" will be obligated to make payment to the
"Lessee" of amounts equal to the rent theretofore paid by the "Lessee" (reduced
as therein provided) and amounts equal to the value as therein defined (reduced
as therein provided) of Improvements constructed pursuant to the Ground Lease
and certain other costs incurred by the "Lessee" (all such amounts being herein
collectively called "Ground Lessor Payments"), all as more fully set forth in
Article 8.5 of the Ground Lease. Landlord hereby grants a security interest, as
provided in the Uniform Commercial Code, in and to Landlord's rights under the
Ground Lease with respect to the Ground Lessor Payments and in and to all Ground
Lessor Payments which become payable to Landlord under and pursuant to the
Ground Lease, and the proceeds thereof, as security for the payment of all
amounts which may become due and owing from Landlord to Tenant pursuant to
Section 25.04 of this Lease. Landlord agrees that Tenant shall have all rights
of a secured party as provided in the Uniform Commercial Code with respect to
the security interest hereinabove granted and agrees, upon request by Tenant
from time to time, to execute and deliver to Tenant financing statements and
renewal financing statements as may be required to perfect and continue the
perfection of the security interest herein granted to Tenant under the
provisions of the Uniform Commercial Code. Tenant agrees, however, that if a
nondisturbance agreement from the "Lessor" under the Ground Lease as described
in Section 25.03 is obtained and furnished to Tenant, then the provisions of
this Section 34.23 shall cease and terminate and shall be of no further force or
effect and Tenant will, upon request, release the security interest in the
Ground Lessor Payments hereinabove granted to Tenant. Further, Tenant agrees
that (if such security interest is not released as provided for above) and if
Landlord is not then in default in the payment of any amount then due by
Landlord to Tenant under this Lease, Tenant will, upon request, subordinate its
security interest in the Ground Lessor Payments granted hereinabove to a
security interest in the Ground Lessor Payments granted to any lender not
related to Landlord which has been granted a first lien upon Landlord's interest
in the Ground Lease, Land and INTELSAT Headquarters Building to secure a loan (a
"Secured Loan") to Landlord; provided, that and if (a) the total principal
amount of the Secured Loan to which Tenant's security interest is to be
subordinated does not exceed eighty percent (80%) of the then current appraised
fair market value of the INTELSAT Headquarters Building [as determined by the
appraisal referred to in clause (b)] and (b) Landlord furnishes to Tenant a
signed copy of a current appraisal of the INTELSAT Headquarters Building by a
qualified, independent appraiser who shall be an MAI-certified real estate
appraiser with ten years experience in the District of Columbia office building
market reflecting that the appraised fair market value of the INTELSAT
Headquarters Building is then at least one hundred twenty-five percent (125%) of
the total principal amount of such Secured Loan. Tenant may not be required to
subordinate its security interest in the Ground Lessor Payments to security
interests securing more than one Secured Loan at any one time, but if the liens
and security interests securing a Secured Loan to which Tenant's security
interest has been subordinated are released, then Tenant will, subject to the
terms and conditions set out hereinabove, thereafter subordinate its security
interest in the Ground Lessor Payments to a security interest securing a new
Secured Loan. For purposes hereof, if a single lender has made one or more loans
secured by one or more deeds of trust of which at least one deed of trust, is It
a first lien upon Landlord's interest in the Ground Lease, Land and INTELSAT
Headquarters

                                     -50-
<PAGE>

Building, all of such deeds of trust securing such lender shall be treated as
constituting a first lien and all of such loans made by such lender shall be
treated as constituting one Secured Loan. In the event that the provisions of
this Section 34.23 have not been terminated pursuant to the provisions hereof,
Landlord may, in addition to and not in limitation of Landlord's rights to
obtain subordination of its security interest in the Ground Lessor Payments,
require Tenant to release its security interest in the Ground Lessor Payments
provided that Landlord deposits with an escrow agent designated by Landlord that
meets with Tenant's reasonable satisfaction, pursuant to an escrow agreement
prepared by Landlord that meets with Tenant's reasonable satisfaction, the sum
of One Million Five Hundred Dollars ($1,500,400) (or an irrevocable letter of
credit in the amount of $1,500,000) to be held by the escrow agent during the
remainder of the term of this Lease as security for the payment by Landlord of
any amounts that may be payable by Landlord to Tenant pursuant to Section 25.04
hereof, but to be returned to Landlord in the event and at such time that a
nondisturbance agreement from the "Lessor" under the Ground Lease as described
in Section 25.03 is obtained and furnished to Tenant. Interest on the escrow
deposit while held in escrow shall be paid to Landlord.

     EXECUTED under seal as of the date first written above.

LANDLORD                                TENANT

International                           WLJA Inc.
Telecommunications
Satellite Organization
                                        By:    /s/ Thomas B. Cookerly
                                              -------------------------------
                                        Name:    Thomas B. Cookerly

By:     /s/ Richard R. Colino           Title:  President & General Manager
    --------------------------------
    Richard R. Colino
    Director General                    Attest:

Attest:                                 By:    /s/ Joe L. Allbritton
                                              -------------------------------
   [sig]                                Name:  Joe L. Allbritton
------------------------------------

                                        Title:  Chairman of the Board

                                        [Corporate Seal]

                                     -51-
<PAGE>

                                  INTEL-L-611

                                   EXHIBIT A

                                  FLOOR PLANS

                                 Page No. A-1

                                     -52-
<PAGE>

                                  INTEL-L-611

                                   EXHIBIT A

                                  FLOOR PLANS

                                  Page No. A-2

                                     -53-
<PAGE>

                                  INTEL-L-611

                                   EXHIBIT A

                                  FLOOR PLANS

                                  Page No. A-3

                                     -54-
<PAGE>

                                  INTEL-L-611

                                   EXHIBIT A

                                  FLOOR PLANS

                                  Page No. A-4

                                     -55-
<PAGE>

                                  INTEL-L-611

                                   EXHIBIT A

                                  FLOOR PLANS

                                  Page No. A-5

                                     -56-
<PAGE>

                                  INTEL-L-611

                                   EXHIBIT A

                                  FLOOR PLANS

                                  Page No. A-6

                                     -57-
<PAGE>

                                  INTEL-L-611

                                   EXHIBIT A

                                  FLOOR PLANS

                                  Page No. A-7

                                     -58-
<PAGE>

                                  INTEL-L-611

                                   EXHIBIT A

                                  FLOOR PLANS

                                  Page No. A-8

                                     -59-
<PAGE>

                                   EXHIBIT B
                                   ---------

                                      LAND
                                      ----

     Being part of the easternmost lot (508,582.70 square feet) shown on a plat
entitled Plat of Computation on a Tract of Land "Taxed as Square 2055" recorded
         -------------------------------------------------------------
in the Office of the Surveyor of the District of Columbia in Survey Book 199 on
Page 81, said lot also being taxed as part of Lot 800 in Square 2055, and being
more particularly described as follows:

     Beginning at an iron pipe planted at the northeast corner of the lot on the
edge of Connecticut Avenue; thence with the boundary of the lot on the southwest
side of Connecticut Avenue

<TABLE>
<S>                                      <C>
1.  South 24 degrees 26'00"              East, 207.14 feet; thence three courses
                                         across the lot
2.  South 45 degrees 04'00"              West, 190.31 feet; thence
3.  South 0 degrees 04'00"               West, 297.50 feet; thence
4.  South 46 degrees 54'22"              East, 174.93 feet to the north side of
                                         Tilden Street, N.W.: thence two courses on
                                         the boundary of the lot on the north side of
                                         Tilden Street
5.  134.02 feet on the arc of a          curve to the left with a radius of 1271.60
                                         feet and a chord bearing South 74030'46"
                                         West, 133.96 feet to a point of reversed
                                         curvature; thence
6.  202.39 feet                          on the arc of a curve to the right with a
                                         radius of 1851.04 feet and a chord bearing
                                         South 74037'33" West, 202.29 feet; thence
                                         two courses across the lot
7.  North 0 degrees 04'00"               East, 54.03 feet; thence
8.  North 89 degrees 56'00"              West, 227.00 feet to the South 0 degrees 04" West,
                                         839.65 foot boundary of the lot; thence with
                                         said boundary reversed
9.  North 0 degrees 04"00"               East, 565.8 feet; thence ten courses across
                                         the lot
10.  South 89 degrees 56"00"             East, 17.00 feet to a point of curvature;
                                         thence
</TABLE>

                                     -60-
<PAGE>

<TABLE>
<S>                                      <C>
11.  25.50 feet                          on the arc of a curve to the left with a
                                         radius of 53.27 feet and a chord bearing
                                         North 76 degrees 21"06" East, 25.26 feet to a point
                                         of compound curvature; thence
12.  42.47 feet                          on the arc of a curve to the left with a
                                         radius of 253.45 feet and a chord bearing
                                         North 54 degrees 52'35" East, 42.34 feet to a point
                                         of compound curvature; thence
13.  32.37 feet                          on the arc of a curve to the left with a
                                         radius of 253.45 feet and a chord bearing
                                         North 43 degrees 27'25" East, 32.35 feet to a point
                                         of tangency, thence
14.  North 39 degrees 47'52"             East, 11.70 feet to a point of curvature;
                                         thence
15.  42.14 feet                          on the arc of a curve to the right with a
                                         radius of 101.85 feet and a chord bearing
                                         North 51 degrees 38'59" East, 41.84 feet to a point
                                         of compound curvature; thence
16.  35.47 feet                          on the arc of a curve to the right with a
                                         radius of 279.34 feet and a chord bearing
                                         North 67 degrees 08'21" East, 35.44 feet to a point
                                         of reversed curvature; thence
17.  27.96 feet                          on the arc of a curve to the left with a
                                         radius of 138.52 feet and a chord bearing
                                         North 64 degrees 59'40" East, 27.91 feet to a point
                                         of compound curvature; thence
18.  58.77 feet                          on the arc of a curve to the left with a
                                         radius of 78.97 feet and a chord bearing
                                         north 37 degrees 53'30" East, 57.42 feet to a point
                                         of compound curvature; thence
19.  50.65 feet                          on the arc of a curve to the left with a
                                         radius of 175.82 feet and a chord bearing
                                         North 8 degrees 19'08" East, 50.47 feet to the North
                                         89 degrees 56' West, 446.84 foot boundary of the
                                         lot; thence with said boundary reversed
20.  South 89 degrees 56'00"             East, 232.84 feet to the point of beginning,
</TABLE>

                                     -61-
<PAGE>

<TABLE>
<S>                                      <C>
                                         containing 7.7168 acres of land and as shown
                                         on a plot prepared by Kidde Consultants,
                                         Inc. dated June 6, 1982 and entitled "Plot
                                         Showing Proposed Division Of Intelstat
                                         Headquarters Building Site For Lease
                                         Purposes."
</TABLE>

                                     -62-
<PAGE>

                                   EXHIBIT C
                                   ---------

                             LEASEHOLD IMPROVEMENTS
                             ----------------------

                                   ARTICLE 1
              (Includes Base Building Work and Tenant Build-Out)

                                  DEFINITIONS

     The terms defined in Article 1 of this Exhibit C, for all purposes of this
Exhibit C, shall have the meanings herein specified, and, in addition to the
terms defined herein, the definitions in the Basic Lease Information and
otherwise in this lease shall also apply to this Exhibit C.

1.01  "Base Building Work" shall mean the improvements in and about the
----  Premises as set forth in Exhibit C-1.

1.02  "Building Plans and Specifications" shall mean plans and specifications
----  for the Building prepared by John Andrews International Pty. Ltd. or
      VVKR Inc. and as modified in accordance with Section 1 of Exhibit C-2.

1.03  "Tenant's Contractor" shall mean such reputable contractor selected by
----  Tenant for interior buildout (subject to Landlord's approval which shall
      not unreasonably be withheld) to construct and install the Tenant
      Build-out in the Premises.

1.04  "Tenant Build-out" means the items which are supplied, installed, and
----  finished in the Premises by or on behalf of Tenant, at Tenant's expense,
      as provided for hereinbelow.  The design of the Tenant Build-out shall
      be consistent with sound architectural and construction practices for
      similar first-class office buildings in the District of Columbia.

1.05  "Interior Construction Plans" shall mean full, complete, and accurate
----  architectural working drawings and specifications for the Tenant
      Build-out for the Premises prepared at Tenant's expense by Tenant's
      Architects including all architectural dimensioned plans showing wall
      layouts, door locations, power and telephone locations and reflected
      ceiling plans; and further including, elevations, details,
      specifications and schedules according to accepted AIA standards, which
      shall be consistent with the Building Plans and Specifications.

1.06  "MEP Plans" shall mean mechanical, electrical and plumbing plans,
----  schedules and specifications for the Tenant Build-out for the Premises.
      MEP Plans which do not impact the Base Building Systems will be prepared
      at Tenant's expense by Tenant's MEP Engineers in accordance and in
      compliance with the requirements of applicable building, plumbing, and
      electrical codes and the requirements of any authority having

                                     -63-
<PAGE>

      jurisdiction over or with respect to such plans, schedules and
      specifications, which are complete, accurate, consistent and fully
      coordinated with the Building Plans and specifications.  All other MEP
      Plans will be prepared by the Landlord's Architect after receipt of
      Tenant Preliminary Plans.  The Tenant shall have an opportunity to
      review the Landlord's Architect's plans, which shall be consistent with
      the intent of the Tenant Preliminary Plans.

1.07  "Structural Plans" shall mean structural plans, schedules and
----  specifications, if any, for the Tenant Build-out for the Premises,
      prepared by Landlord's Architect at Landlord's expense after receipt of
      Tenant Preliminary Plans and in accordance with the requirements of
      Exhibit C-2.  The Tenant shall have an opportunity to review the
      Landlord's Architect's plans, which shall be consistent with the intent
      of the Tenant Preliminary Plans.

1.08  "Tenant's Architect" shall mean Settles Associates Inc. or such other
----  reputable person or persons engaged by Tenant and approved by Landlord
      (such approval not to be unreasonably withheld) to prepare the Tenant
      Interior Construction Plans.

1.09  Tenant's MEP Engineers" shall mean Setty and Associates or such other
----  engineers engaged by Tenant and approved by Landlord (such approval not
      to be unreasonably withheld) to prepare the MEP Plans, complete with all
      calculations which impact existing equipment and structure, for the
      Tenant Build-out not affecting Base Building Systems.

1.10  "Tenant's Structural Engineers" shall mean Cagley and Associates or such
----  other structural engineers engaged by Tenant and approved by Landlord
      (such approval not to be unreasonably withheld) to prepare the Tenant
      Preliminary Plans for Tenant requested structural changes.

1.11  "Landlord's Architect" shall be VVKR Inc. in association with MMP and
----  The Benham Group or any other reputable architect or engineering firms
      engaged by the Landlord.

1.12  "Base Building Systems" shall be defined as any usable building systems
----  or components which are external to Tenant space within the core of the
      Building and/or common to and/or serve or exist for the benefit of other
      tenants or occupants of the Building.

1.13  "Tenant Preliminary Plans" shall mean structural and MEP information in
----  sufficient detail to enable the Landlord's Architect to prepare detailed
      Building Plans and Specifications.  The final version of the Tenant
      Preliminary Plans shall be marked "Final Preliminary Plans."

                                     -64-
<PAGE>

1.14  "Plans" shall mean the Interior Construction Plans together with the MEP
----  Plans, for which Tenant is responsible and if applicable, the Final
      Preliminary Plans.

1.15  "Landlord's Contractor" shall mean the W.P. Lipscomb Company or any
----  other reputable Contractor selected by the Landlord.

                                   ARTICLE 2
                              SUBMISSION OF PLANS

2.01  Upon Tenant's request, Landlord will furnish Tenant, one (1) set of
----  Building Plans and Specifications pertaining to Tenant's space to assist
      Tenant in preparing the Plans.  It is understood and agreed that
      Landlord in no way warrants the accuracy of such Building Plans and
      Specifications and Landlord shall not have any liability to Tenant, or
      anyone claiming through Tenant as a result of such plans.  Tenant, shall
      perform a field verification to independently determine the
      specifications and dimensions of the Premises.

2.02  Tenant, all Tenant's expense, has prepared and delivered to Landlord the
----  final version of the Tenant Preliminary Plans impacting the structure,
      and shall hereafter upon request promptly provide to Landlord any
      underlying detailed information Landlord may reasonably request in order
      to evaluate such plans.  On or before 15 January 1987, Tenant, at
      Tenant's expense, shall prepare and deliver to Landlord the final
      version of the remaining Tenant Preliminary Plans, preliminary space
      plans and Tenant's interior MEP Plans, and shall thereafter upon request
      promptly provide to Landlord any underlying detailed information
      Landlord may reasonably request in order to evaluate such plans.  The
      final version of the Interior Construction Plans shall be delivered to
      the Landlord by Tenant, at Tenant's expense, on or before 2 April 1987.
      No later than fifteen (15) business days after Landlord's receipt of
      each set of plans, Landlord shall notify Tenant in writing as to whether
      Landlord approves or disapproves such plans.  If Landlord requires any
      changes to such plans, Tenant shall, at Tenant's expense, prepare and
      deliver to Landlord the required revisions within ten (10) business days
      after Landlord's request for such revisions.  If the Landlord approves
      such plans, the Tenant and Landlord shall be authorized to Proceed with
      their respective responsibilities in accordance with such plan's and
      this Exhibit C.  Final plans referred to herein shall be in marked
      "Final Plans."

2.03  Upon completion of Tenant's Work the Tenant shall, upon receipt, furnish
----  Landlord with accurate "as built" plans of the Tenant's Work, which
      plans shall be incorporated into this Exhibit C by this reference for
      all intents and purposes.  Construction "as built" applicable to the
      Premises and maintained by the Landlord shall be available for perusal
      and copy by the Tenant.

                                     -65-
<PAGE>

2.04  All design, construction, and installation of Tenant Build-out shall
----  conform to the requirements of applicable building, plumbing and
      electrical codes and the requirements of any authority having jurisdiction
      over, or with respect to, such work.

                                   ARTICLE 3

                                LANDLORD'S WORK

Landlord shall, at its sole cost and expense, furnish, install and complete the
Base Building Work as defined in Exhibit C-1 and the Landlord's work as
described in Paragraphs 1A-1H of Exhibit C-2 ("Landlord's Work").

                                   ARTICLE 4

                                 TENANT'S WORK

4.01  All Tenant Build-out other than Landlord's Work ("Tenant's Work") shall
----  be at Tenant's sole cost and expense (but subject to payment of Landlord's
      Contribution pursuant to Articles 5.01 through 5.03 of Exhibit C) it being
      understood and agreed that any Tenant Work which affects the structure of
      the Building of the Base Building Systems shall be performed by Landlord,
      at Tenant's expense. The Tenant may elect to contract directly with
      outside Contractors for the interior Tenant Build-out Work.

4.02  The Tenant's Work shall comply with the requirements set forth in
----  Exhibit C-2.

                                   ARTICLE 5

                         TENANT IMPROVEMENT ALLOWANCE

5.01  In addition to Landlord's contribution described in Article 3 of this
----  Exhibit C, Landlord shall pay in accordance with this Article 5 on behalf
      of Tenant an amount up to [redacted text] multiplied Rentable Area of the
      Premises toward the construction of Tenant's Work and related consulting
      fees (hereinafter "Landlord's Contribution"). Landlord's Contribution
      shall be paid on behalf of Tenant as set forth below.

5.02  Landlord shall pay the Landlord's Contribution to Tenant periodically as
----  written requests for payment (the "Payment Requests") are submitted to
      Landlord by Tenant based upon copies of invoices from Tenant's Contractor,
      consultants and/or other contractors constructing or supplying Tenant's
      Work and material, which Payment Requests shall include a detailed
      description of the portion of the Tenant's Work performed during

                                     -66-
<PAGE>

      the period to which any such Payment Request relates and proof of payment
      of previous invoices submitted to and paid by Landlord. Landlord shall pay
      the amount so requested by Tenant to Tenant within fifteen (15) days after
      a Payment Request is submitted to Landlord.

5.03  For purposes of this Exhibit C, the Rentable Area of the Premises is
----  estimated to be 73,153 square feet.  The amount of any payments payable
      to Tenant pursuant to this Article 5 shall be adjusted upon the
      determination of the Rentable Area of the Premises pursuant to Section
      1.02 or Section 6.04 of the lease (it being agreed that if Tenant
      exercises its option to lease the Expansion Space under Article 33 of
      the lease the Rentable Area of the Expansion Space shall be included in
      the Rentable Area of the Premises for purposes of this Article 5.03).
      If the payments made to or on behalf of Tenant on the basis of the
      estimated Rentable Area of the Premises exceed [redacted text]
      multiplied by the actual number of square feet of the Rentable Area of
      the Premises, Tenant shall pay Landlord such excess promptly after such
      determination.  If the payments made to or on behalf of Tenant on the
      basis of the estimated Rentable Area of the Premises are less than
      $25.00 multiplied by the actual square feet of Rentable Area of the
      Premises, Landlord shall pay Tenant such shortfall promptly after such
      determination.

5.04  Tenant shall have the right, at its option, to use, in its interior
----  design, the equipment and materials purchased by INTELSAT in bulk for
      the build out of the interior of Phase II.  The equipment and materials
      available are as follows:

<TABLE>
<CAPTION>
                                     Quantity            Unit
      Description                    Available           Price
     ------------------------------  ------------------  ------------
<C>  <S>                             <C>                 <C>
1.   Metal door frames
     Type 1-1  Left Hand             300 Sets
     with Glass
     Sidelight
     Type 1A-1  Right Hand           200 Sets
     with Glass
     Sidelight
     Type 2-2  Left Hand             50 Sets
     Single Door
     Frame
     Type 2A-1  Right Hand           58 Sets
     Single Door
     Frame
</TABLE>

                                     -67-
<PAGE>

<TABLE>
<C>  <S>                             <C>                 <C>
2.   Light Fixtures
     Type A  Gibson                  (Adequate Supply)
     Paralux Series
     18 Cell, (2'X4')
     Recessed/Air
     Supply 277 Volts
3.   Sconce Lights - Cylinder        144 Fixtures
     Type Wall Lamp 14" Tall
4.   Patrick Carpet                  (Adequate Supply)   per sq. yd.
     Title (18"X18")
</TABLE>

      The above equipment or materials are available for purchase by the
      Tenant from the Landlord at the above stated acquisition unit prices
      paid by the Landlord.

5.05  The Landlord will make every reasonable effort to enable the Tenant Work
----  to commence as soon as possible.  The parties understand that Base
      Building Work and Tenant's Work will be conducted concurrently and
      accordingly in order to ensure harmony between subcontractors of like
      trades the Tenant shall consider using the Landlord's Contractor and his
      subcontractors for the Tenant's Work whenever possible.  In the event
      other contractors/subcontractors are selected by the Tenant, the other
      contractors/subcontractors shall conduct their work without interruption
      of or disruption to the Landlord's Contractor and its subcontractors'
      work.

5.06  The Landlord's procurement staff is available to provide its best
----  efforts for use by the Tenant to obtain bids, negotiate contract prices,
      award and administer such contracts on behalf of the Tenant.  This
      service is available to the Tenant at no additional charge or fees over
      and above the actual cost of the contracts awarded on behalf of the
      Tenant.  Decision as to bidders, contract awards and amendments or
      changes to contracts will be subject to the participation and approval
      of the Tenant.  Any and all costs for the services provided in
      accordance with the procurement services set forth herein shall be paid
      by the Tenant to the Landlord within fifteen (15) days after a request
      therefor is submitted to the Tenant.

5.07  At all times prior to the Commencement Date Landlord shall, at its
----  expense, provide electricity and to the extent that heating, ventilating
      and air-conditioning facilities are installed in the Building, heating,
      ventilating and air-conditioning to the Building and Premises as
      reasonably required by Tenant and its contractors incident to
      performance and completion of Tenant's Work.

                                     -68-
<PAGE>

                                   ARTICLE 6

                           TENANT REQUESTED CHANGES

     Tenant shall not deviate from the Plans approved in accordance with Article
2.02 of this Exhibit C without Landlord's prior written approval, which approval
shall be granted by Landlord if and to the extent that Landlord's approval is
required under Section 12.01.  All change requests shall be submitted to
Landlord together with preliminary drawings and other information as may be
reasonably necessary to enable Landlord to either approve or disapprove such
changes.  Landlord shall thereafter either approve or not approve the
preliminary drawings within fifteen (15) days.  In the event Landlord approves
such changes, and provided such changes do not affect the structure of the
Building or the Base Building Systems, Tenant may perform the work, and upon
completion furnish Landlord with "as built" drawings.  If the change order
request involves changes to either the structure of the Building or the Base
Building Systems, and if Landlord approves the changes based on the preliminary
drawings, Landlord shall prepare detailed plans and specifications for such
work, at Tenant's sole cost and expense, and Landlord shall thereafter perform
such work at Tenant's sole cost and expense.  If any change requested by Tenant
which deviates from the approved Plans delays the date of substantial completion
of the Base Building Work, such delay shall be the sole responsibility of Tenant
and be considered a "Tenant Delay." Implementation of Interior Construction
Plans shall be the responsibility and at the sole expense of the Tenant.

                                     -69-
<PAGE>

                                   ARTICLE 7

                            COMMENCEMENT OF RENTAL

     In the event and to the extent Landlord is delayed in substantially
completing the Base Building Work or the Landlord's Work as a result of

     1.   Tenant's failure to deliver to Landlord the Plans on or before the
          dates specified in Article 2.02 of this Exhibit C, or

     2.   Tenant requested changes as described in Article 6 after approval of
          Plans in accordance with Article 2.02 of this Exhibit C, then

     the Tenant's obligation to pay Rental shall be accelerated by the number of
days of such Tenant delay.

                                     -70-
<PAGE>

                                  EXHIBIT C-1
                                  -----------

                              BASE BUILDING WORK
                              ------------------

     The Landlord shall at its sole cost and expense provide a Building Shell
consisting of the following (the "Base Building Work"):

     (1)  Class exterior walls and core walls taped, spackled and ready for
          finish or building standard paint, in such manner as befits a first-
          class office building in the District of Columbia.

     (2)  Unfinished, level and smooth concrete floors installed throughout the
          Premises, broom clean, with office floors designed for a per square
          foot load of 80 pounds live and 20 pounds dead.

     (3)  120/208 volt and 277/480 volt power supplied on each Floor to the
          Building core and terminated in branch circuit panel boards.

     (4)  Men's and ladies' restroom facilities furnished in accordance with the
          Building Plans and Specifications and located on each floor on which
          the Premises are located.

     (5)  Heating, Ventilating, and Air Conditioning

          (A)  High pressure supply air duct work from high pressure variable
               air volume air handling located in mechanical rooms, to the
               perimeter of the Premises.

          (B)  Interior areas are conditioned by low pressure supply air duct
               work from low pressure constant volume variable temperature air
               handling units located in mechanical rooms located outside the
               Premises.

     (6)  Voice evacuation system, smoke detectors, exit lights, fire
          sprinklers, fire standpipe valves and pull stations to meet the
          District of Columbia Fire Code.

     (7)  All exterior walls completed with thermal insulation and double
          glazing.

     (8)  All floor openings, and stair openings located in the core installed
          with fire rated drywall enclosures and standard fire rated doors.

     (9)  Water, waste and vent Plumbing risers outside of the core area on each
          of the floors.

     (10) Lobby level closure doors, one double door per pod.

     (11) Landlord will bring HVAC ducts and piping to the perimeter of the
          Premises, in accordance with HVAC system provided by the Landlord
          which will accommodate the present needs of the Tenant's television
          station (WLJA), which

                                     -71-
<PAGE>

          in turn will be described in the final MEP Plans to be submitted on or
          before 15 January 1987 and shall be reasonably consistent with the
          Setty Report 4 August 1986 entitled "Preliminary Analysis of
          Mechanical/Electrical Systems for WJLA-TV."

     (12) All design, construction and installation of Base Building Work and
          Landlord's Work shall conform to the requirements of applicable
          building, plumbing and electrical codes and the requirements of any
          authority having jurisdiction over, or with respect to, such work.

                                     -72-
<PAGE>

                                  EXHIBIT C-2
                                  -----------

                            3400 INTERNTIONAL DRIVE
                            -----------------------

                    REQUIREMENTS FOR LEASEHOLD IMPROVEMENTS
                    ---------------------------------------

     1.  The Landlord's Work referred to in Article 3 shall consist of the
following:

          A.   Depressed slab for computer and equipment rooms in Pod P.  Level
               1 (to maximum of 12") and Level 2 and 4 (to maximum of 8") .

          B.   Elimination of the floors in the area on levels 3 and 5 of Pod P
               in accordance with the preliminary plans submitted or to the
               submitted pursuant to the first sentence of Article 2.02 of this
               Exhibit C.

          C.   Provide personnel access between Phase I and II for use of the
               main INTELSAT cafeteria by Tenant's employees and personnel.

          D.   Re-cut and weld steel beams to increase vertical room area in
               Level 2 Pod N for raised ceiling.

          E.   Provide the framing for opening in floor for newsroom stairway in
               Pod N between Level 1 and 2.

          F.   Provide the framing for opening for the link stairway in Pod P
               level 2 through 5, and if the option for added floor is
               exercised, through Level 6.  In the event the NCPC approval for
               the link stairway is not obtained by the Tenant before 31 January
               1987, the Atrium stairway will be provided in lieu thereof at the
               sole cost and expense of the Tenant, except the Landlord will be
               responsible for design, security and fire safety aspects of the
               Atrium stairway and will pay to the Tenant a fixed amount of
               Twenty-Five Thousand Dollars ($25,000) provided the NCPC approval
               of the link stairway is not obtained and the Atrium stairway is
               constructed in lieu thereof.

          G.   Provide the framing for opening for the elevator from Pod P
               Level 1 through Level 4.

          H.   Provide separate metering for Tenant power usage to the maximum
               practical extent.

     2.  Any and all other improvements shall be at the sole cost and expense of
the Tenant.  Such improvements which affect or require Building structural
changes or which impact the Base Building Systems are subject to the following:

          A.   Such Tenant requested improvements to Pod N shall be kept to the
               minimum and only made if the present proposed Building structure
               and

                                     -73-
<PAGE>

               MEP Systems, as set forth in the Building Plans and
               Specifications, cannot possibly be used.

          B.   Such Tenant requested improvements shall be submitted to the
               Landlord in writing, complete with adequate preliminary drawings,
               (at the earliest practicable date) in order to minimize the
               effect on the Building construction schedule.  Such Tenant
               requested improvements will be submitted by the Landlord to
               Landlord's Architect for preparation of the necessary
               construction drawings and then the Landlord will issue change
               instructions to the Landlord's Contractor to accomplish the
               required work.

          C.   The charges for such other Tenant requested improvements will be
               borne solely by the Tenant.  These charges will include all
               direct costs to the Landlord including the following:

               1.   Costs of the efforts of the Landlord's Architect and its
                    consultants.

               2.   Costs of reproduction of necessary drawings.

               3.   Costs of labor, materials, overhead, and fees of the
                    Landlord's Contractor and its subcontractors, including
                    costs of necessary rescheduling of work.

               4.   Charles of the Landlord's Consultants for inspection and
                    acceptance of such Tenant requested improvements.

               5.   There will be no overhead or fee added by Landlord to the
                    costs referred to above for the Landlord's work in
                    connection therewith.

          D.   Such costs for Tenants requested leasehold improvements will be
               paid by the Tenant to the Landlord within fifteen (15) days after
               requests for payment for costs theretofore incurred by Landlord
               are submitted to the Tenant.

                                     -74-
<PAGE>

                                   EXHIBIT D
                                   ---------

                     DECLARATION AS TO DATE OF DELIVERY AND

                      ACCEPTANCE OF POSSESSION OF PREMISES
                      ------------------------------------

     Attached to and made a part of the lease dated the ____ day of
_______________, 19__, entered into by and between International
Telecommunications Satellite Organization, as Landlord, and
________________________________________________, as Tenant.

     Landlord and Tenant do hereby declare and evidence that possession of the
Premises was accepted by Tenant on the _______ day of _______________________,
19__, and the lease is now in full force and effect.  For the purpose of this
lease, the Commencement Date is established and declared as the ____________ day
of __________, 19__.

                                      LANDLORD:

ATTEST:                               International Telecommunications Satellite
                                      Organization

                                      By:
--------------------------------          -------------------------------------
                                      TENANT:

ATTEST:                               WJLA Inc.

By:                                   By:
   -----------------------------          -------------------------------------

Name:                                 Name:
     ---------------------------           ------------------------------------

Title:                                Title:
      --------------------------            -----------------------------------

[Corporate Seal]

                                     -75-
<PAGE>

                                   EXHIBIT E
                                   ---------

                      METHOD OF CALCULATING RENTABLE AREA

                            OF PREMISES AND BUILDING
                            ------------------------

     The Rentable Area of the Premises shall be calculated in accordance with
the Washington Board of Realtors Standard Method of Measurement except that the
Rentable Area of the Premises which would otherwise be determined in accordance
with the Washington Board of Realtors Standard Method of Measurement, a copy of
which is attached hereto, shall include two-thirds (2/3rds) of the floor space
to be removed on the third (3rd) and fifth (5th) levels of Pod P.  The Rentable
Area of the Building shall be calculated in accordance with the Washington Board
of Realtors Standard Method of Measurement except that two-thirds (2/3rds) of
the floor space to be removed on the third (3rd) and fifth (5th) levels of Pod P
shall also be included in the Rentable Area of the Building.  The Rentable Area
of the INTELSAT Headquarters Building shall be calculated in accordance with the
Washington Board of Realtors Standard Method of Measurement except that two
thirds (2/3) of the floor space to be removed on the third (3rd) and fifth (5th)
levels of Pod P shall also be included in the Rentable Area of the INTELSAT
Headquarters Building.

     In determining the Rentable Area of the Building and the Rentable Area of
the INTELSAT Headquarters Building, the Rentable Area of each floor of the
Building and the Rentable Area of each floor of the INTELSAT Headquarters
Building shall be calculated for purposes hereof as if each such floor were a
single tenancy floor.

                                     -76-

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