Document:

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                                                                    EXHIBIT 10.9

                      STOCK PURCHASE AND OPTION AGREEMENT

          THIS STOCK PURCHASE AND OPTION AGREEMENT (the "Agreement") is made
this 4th day of December 1995, by and between MIL 3, INCORPORATED (the
"Company"), a corporation organized and existing under the laws of the State of
Delaware, and GEORGE M. CATHEY (the "Purchaser"), an individual residing in
Washington, D.C.  The Company and Purchaser are sometimes collectively referred
to herein as the "Parties" and each individually as the "Party."

                                  WITNESSETH:

          WHEREAS, Purchaser is and has been employed by the Company as a
principal engineer and project manager and is familiar with the Company and its
business, and

          WHEREAS, the Company desires to sell, and Purchaser desires to
purchase, fifteen thousand (15,000) shares of the Company's Common Stock (the
"Common Stock"), par value $.01 (said 15,000 shares, the "Stock"), in accordance
with the terms of this Agreement.

          NOW, THEREFORE, in consideration of the foregoing and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the Parties hereto, intending legally to be bound hereby, agree as
follows:

                                   ARTICLE I
                           Sale of the Stock; Option
                           -------------------------

          1.1  Sale of the Stock.  Subject to the terms and conditions hereof,
               -----------------
provided that the Purchaser remains an employee of the Company, the Company will
sell to Purchaser, and Purchaser will purchase from the Company, fifteen
thousand (15,000) shares of the Stock at a purchase price of $1.90 per share
(the "Purchase Price"), or a total of $28,500.

          1.2  Option.
               ------

               (a)  Option to Purchase. Subject to the terms and conditions
                    ------------------
hereof, the Company grants to the Purchaser an option (the "Option") to purchase
ten thousand (10,000) shares of Common Stock (the "Option Stock") at an exercise
price of $1.90 per share. The Option only may be exercised during the period
described below that occurs after the first to occur of the following events,
and if not exercised during such period shall immediately terminate and become
null and void (such period during which the Option may be exercised is hereafter
referred to as the "Option Term"):

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               (i)   the sixty (60) day period following notice by the Company
          to the Purchaser of a merger or other business combination involving
          the Company; or

               (ii)  the sixty (60) day period following notice by the Company
          to the Purchaser of the scheduled effectiveness of the Company's
          Initial Public Offering (as defined below); or

               (iii) the twelve (12) month period commencing on or after
          December 4, 2005.

               (b)  Certain Other Termination Provisions.
                    ------------------------------------

                    (i)   The Option and all rights hereunder with respect
          thereto, to the extent such rights shall not have been exercised,
          shall terminate and become null and void on the last day of the Option
          Term.

                    (ii)  If the Purchaser's employment with the Company has
          terminated for any reason, the Option, if not previously exercised,
          shall immediately terminate and become null and void except where the
          termination of such employment is by reason of Purchaser's death
          during the Option Term.

                    (iii) Upon a termination of the Purchaser's employment by
          reason of death during the Option Term, the Option may be exercised by
          the Purchaser's estate during the Option Term.

                    (iv)  A transfer of the Purchaser's employment between the
          Company and any parent or subsidiary of the Company, or between any
          parents or subsidiaries of the Company, shall not be deemed to be a
          termination of the Purchaser's employment.

                    (v)   Notwithstanding any other provisions set forth herein,
          if the Purchaser shall (A) commit any act of malfeasance or wrongdoing
          affecting the Company or any parent or subsidiary of the Company, (B)
          breach any covenant not to compete or employment contract with the
          Company or any parent or subsidiary of the Company, or (C) engage in
          conduct that would warrant the termination of Purchaser's employment
          for cause, the Option shall immediately terminate and become null and
          void.

               (c)  Exercise.
                    --------

                    (i)   The Purchaser (or his estate, if applicable) may only
          exercise the Option with respect to all, but not less than all, of the
          Option Stock by giving written notice to the Company during the Option
          Term of intent to exercise. The notice of exercise shall specify that
          Purchaser (or his estate, if applicable) is

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          exercising the Option and the date of exercise thereof, which date
          shall be at least five (5) business days after the giving of such
          notice unless an earlier time shall have been agreed between the
          Company and the Purchaser (or his estate, if applicable).

                    (ii)  If the Purchaser (or his estate, if applicable) fails
          to pay for any of the Option Stock specified in such notice or fails
          to accept delivery thereof, the Option shall immediately terminate and
          become null and void.

               (d)  Adjustments. In the event of a reorganization,
                    -----------
recapitalization, change of shares, stock split, stock dividend,
reclassification, subdivision or combination of shares or any other change in
the corporate structure or shares of capital stock of the Company, the Company
shall make such adjustment as is appropriate in the number and kind of shares of
Common Stock subject to the Option or in the option exercise price; provided,
                                                                    --------
however, that no such adjustment shall give the Purchaser any additional
-------
benefits under the Option.

               (e)  Merger or Other Business Combination.  If the Option has
                    ------------------------------------
not been exercised or terminated, the Company shall provide Purchaser with
thirty (30) days notice prior to the consummation of any merger or other
business combination involving the Company during the period prior to December
4, 2005. Purchaser (or his estate, if applicable) shall have the right to
exercise the Option and pay for the Option Stock during the sixty (60) day
period after such notice, following which the Option shall terminate and become
null and void.

               (f)  Public Offering.
                    ---------------

                    (i)  If the Option has not been exercised or terminated, the
          Company shall provide Purchaser with thirty (30) days notice prior to
          the effectiveness of the Company's Initial Public Offering if it is
          scheduled to become effective during the period prior to December 4,
          2005. Purchaser (or his estate, if applicable) shall have the right to
          exercise the Option and pay for the Option Stock during the sixty (60)
          day period after such notice, following which the Option shall
          terminate and become null and  void.

                    (ii) "Initial Public Offering" as used herein means the
          first public offering of Common Stock of the Company, which offering
          is effected pursuant to a registration statement other than on Form S-
          8 filed with, and declared effective by the Securities and Exchange
          Commission under the Securities Act of 1933, as amended.

               (g) Transfer. During the Purchaser's lifetime, the Option shall
                   --------
be exercisable only by the Purchaser or any guardian or legal representative of
the Purchaser, and the Option shall not be transferable except, in case of the
death of the Purchaser, by will, or the laws of descent and distribution, nor
shall the Option be subject to attachment, execution or other similar processes.
In the event of (i) any attempt by the Purchaser to alienate, assign, pledge,
hypothecate or otherwise dispose of the Option, except as provided for herein,
or (ii) the levy of any attachment, execution or similar process upon the rights
or interests hereby conferred, the Company may

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terminate the Option by notice to the Purchaser, and it shall thereupon become
null and void.

               (h)  No Rights as to Employment. Neither the granting of the
                    --------------------------
Option nor its exercise shall be construed as granting to the Purchaser any
right with respect to continuance of employment with the Company.

          1.3  No Rights as Shareholder.  Notwithstanding anything to the
               ------------------------
contrary set forth in this Agreement, until Purchaser (or his estate, if
applicable) shall have fully paid for the shares of Stock or the Option Stock in
accordance with this Agreement, Purchaser (or his estate, if applicable) shall
not be considered a shareholder with respect to such shares, shall have no
rights to exercise any voting or other rights with respect thereto, and shall
not be entitled to any compensation or consideration for any such rights which
have not been exercised by full payment to the Company in accordance with this
Agreement.

                                  ARTICLE II
                             Closings; Deliveries
                             --------------------

          2.1  Closings.
               --------

               (a)  The closing of the purchase and sale of the Stock
contemplated by Section 1.1 shall be held at 2 p.m. on December 15, 1995 at the
offices of the Company at 3400 International Drive, N.W., Washington, D.C.
20008.

               (b)  The closing of the purchase and sale of the Option Stock
contemplated by Section 1.2 shall be held at 2 p.m. at the offices of the
Company 10 business days after Purchaser has provided written notice to the
Company of his exercise of the Option.

          2.2  Deliveries.  At each closing, (a) the Company shall deliver to
               ----------
Purchaser (or his estate, if applicable) a certificate for the number of shares
of Common Stock, par value $.01, to be purchased by Purchaser (or his estate, if
applicable) at such closing, registered in the name of Purchaser (or his estate,
if applicable), and (b) Purchaser (or his estate, if applicable) shall deliver
to the Company the Purchase Price per share, in the form of a cashier's or
certified check or money order payable to the Company, along with a letter
signed by Purchaser (or his estate, if applicable) reciting the representations
and warranties contained in Sections 3.1 and 3.2 of this Agreement.

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                                  ARTICLE III
                  Representations and Warranties of Purchaser
                  -------------------------------------------

          Purchaser represents and warrants to the Company as follows:

          3.1  Investment.  Purchaser is acquiring the Stock and the Option
               ----------
Stock, as applicable, for his own account for investment and not with a view to
any distribution thereof; Purchaser has no agreement, undertaking, arrangement,
obligation or commitment providing for the disposition thereof; and Purchaser
understands that the Stock and the Option Stock, as applicable, has not been
registered under the Securities Act of 1933, as amended, and will bear the
legends specified in Section 3.3.

          3.2  Receipt of Information.  Purchaser has been furnished access to
               ----------------------
the business and other records of the Company and such additional information
and documents as Purchaser has requested, and has been afforded an opportunity
to ask questions of and receive answers from representatives of the Company
concerning the terms and conditions of this Agreement, the purchase of the Stock
and the Option Stock, as applicable, the Company's business, financial condition
and prospects, and all other matters deemed relevant by the Purchaser.

          3.3  Legends. Each certificate representing (a) the Stock, (b) the
               -------
Option Stock, and (c) any other securities issued in respect of the Stock and/or
the Option Stock, whether upon any stock split, stock dividend, conversion,
recapitalization, merger, consolidation or similar event, unless the securities
evidenced by such certificate shall have been registered under the Securities
Act of 1933, as amended, shall be imprinted with legends in the following form
(in addition to any other legend required under applicable state securities
laws):

          "THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE UNITED
          STATES SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE
          SECURITIES LAWS. THEY MAY NOT BE SOLD OR OFFERED FOR SALE IN THE
          ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT AS TO THE
          SECURITIES UNDER SAID ACT AND ANY APPLICABLE STATE SECURITIES LAW
          OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH
          REGISTRATION IS NOT REQUIRED."

          "THESE SECURITIES ARE SUBJECT TO CERTAIN TRANSFER RESTRICTIONS
          SET FORTH IN AN AGREEMENT DATED DECEMBER 4, 1995, BY AND BETWEEN
          THE HOLDER HEREOF AND THE COMPANY, AND MAY ONLY BE SOLD,
          TRANSFERRED OR ASSIGNED IN ACCORDANCE THEREWITH. A COPY OF SAID
          AGREEMENT IS ON FILE AND MAY BE INSPECTED AT THE OFFICES OF THE
          COMPANY."

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                                  ARTICLE IV
                       Transfer Restrictions; Repurchase
                       ---------------------------------

          4.1  Transfer Restrictions. Notwithstanding anything to the contrary
               ---------------------
set forth herein, no shares of Stock or Option Stock acquired by the Purchaser
(or his estate, if applicable) hereunder may be sold, transferred, assigned,
pledged or otherwise disposed of, unless the Purchaser (or his estate, if
applicable) has first obtained the written approval of the Company's board of
directors.

          4.2  Repurchase.
               ----------

               (a) Except as provided in Section 4.2(c), the Company shall have
the right to purchase all shares of the Stock and Option Stock (if any) then
held by the Purchaser (or the Purchaser's estate, if applicable) if the
Purchaser's employment with the Company has terminated for any reason, other
than death or disability, during the six (6) year period commencing on the date
first set forth above, at a price per share equal to the lesser of (i) the
Purchase Price (subject to increase in accordance with Section 4.4(a)) or (ii)
the "fair market value" of the shares of the Company's Common Stock as most
recently determined in accordance with Section 4.4(b).

               (b) Except as provided in Section 4.2(c), the Company shall have
the right to purchase all shares of the Stock and Option Stock (if any) then
held by the Purchaser (or the Purchaser's estate, if applicable) if the
Purchaser's employment with the Company has terminated due to his death or
disability during the six (6) year period commencing on the date first set forth
above, at a price per share equal to the fair market value of the Company's
Common Stock as most recently determined in accordance with Section 4.4(b).

               (c) Notwithstanding Sections 4.2(a) and (b), if the Purchaser's
employment with the Company terminates for any reason (including due to his
death or disability) during the six (6) year period commencing on the date first
set forth above and, if on the date of such termination, Marc A. Cohen and Alain
Cohen do not own in the aggregate at least 50% of the issued and outstanding
shares of Common Stock of the Company, then the Company shall have the right to
purchase, and the Purchaser shall have the right to require the Company to
purchase, all (but not less than all) shares of Stock and Option Stock (if any)
then held by Purchaser (or the Purchaser's estate, if applicable) at a price per
share equal to the fair market value thereof as most recently determined in
accordance with Section 4.4(b).

               (d) Commencing six (6) years after the date first set forth
above, the Company shall have the right to purchase all shares of the Stock and
Option Stock (if any) then held by the Purchaser (or the Purchaser's estate, if
applicable) if the Purchaser's employment with the Company has terminated for
any reason, including due to his death or disability, at a price per share equal
to the fair market value of the Company's Common Stock as most recently
determined in accordance with Section 4.4(b).

                                       6
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          4.3  Exercise of Repurchase Rights.
               -----------------------------

               (a) The Company may exercise its right to repurchase the Stock
and the Option Stock in accordance with Sections 4.2(a), (b) or (d) at any time
by giving written notice of such exercise to Purchaser (or his estate, if
applicable) during the twelve (12) month period following the termination of
Purchaser's employment. The Company's purchase of the Stock and the Option Stock
in accordance with Section 4.2 (a), (b) or (d) shall be concluded within ninety
(90) days after the date of such notice, at a closing at the Company's principal
office, at a time and date designated by the Company upon three (3) business
days prior notice to Purchaser (or his estate, if applicable).

               (b) (i)   The Company may exercise its right to purchase the
                    Stock and the Option Stock in accordance with Section 4.2(c)
                    by giving written notice of such exercise to Purchaser (or
                    his estate, if applicable) during the thirty (30) day period
                    following the date of termination of Purchaser's employment.
                    If the Company has elected to purchase the Stock and the
                    Option Stock, the Company's purchase of the Stock and the
                    Option Stock in accordance with Section 4.2(c) shall be
                    concluded within ninety (90) days after the date of such
                    notice, at a closing at the Company's principal office, at a
                    time and date designated by the Company upon three (3)
                    business days prior notice to Purchaser (or his estate, if
                    applicable).

                    (ii) Purchaser may elect to require the Company to purchase
                    the Stock and the Option Stock in accordance with Section
                    4.2(c) by giving written notice of such election to the
                    Company during the thirty (30) day period following the date
                    of termination of Purchaser's employment. If Purchaser has
                    provided such notice, the Company's purchase of the Stock
                    and the Option Stock in accordance with Section 4.2(c) shall
                    be concluded within the twelve (12) month period after the
                    date of such notice, at a closing at the Company's principal
                    office, at a time and date designated by the Company upon
                    three (3) business days prior notice to Purchaser (or his
                    estate, if applicable).

               (c)  At each such closing contemplated in this Section 4.3, (i)
Purchaser (or his estate, if applicable) shall deliver all certificates
evidencing the shares of Stock and the Option Stock, free and clear of any
claim, lien or encumbrance, with stock powers duly executed, and Purchaser (or
his estate, if applicable) shall indemnify and hold the Company harmless against
any claims, liabilities or expenses with respect to Purchaser's (or his
estate's) ownership of such shares, and (ii) the Company shall pay for the
shares of Stock and Option Stock by cashier's check, certified check or money
order.

                                       7
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          4.4  Purchase Price Payable Upon Repurchase.
               --------------------------------------

               (a)  CPI Adjustments.
                    ---------------

                    (i)   The Purchase Price to be paid by the Company in
          accordance with Section 4.2(a) upon a purchase of each share of Stock
          and Option Stock shall be increased proportionately in accordance with
          the cumulative increase in the Consumer Price Index ("CPI"), measured
          from (A) the monthly CPI most recently published prior to the closing
          date of Purchaser's (or his estate's) acquisition of each such share
          to (B) the monthly CPI most recently published prior to the date of
          such purchase by the Company.

                    (ii)  The CPI shall mean the index known as the United
          States Bureau of Labor Statistics, Consumer Price Index for Urban Wage
          Earners and Clerical Workers, all items, for Washington, D.C. SMSA (
          1982-84=100).

                    (iii) If the CPI as now constituted, compiled and published
          shall be revised or cease to be compiled and published during the term
          of this Agreement, then the Parties shall request the Bureau of Labor
          Statistics to furnish a statement converting the CPI to a figure that
          would be comparable to another index published by the Bureau of Labor
          Statistics and such other index shall be used in computing the
          increase contemplated herein. Should the Parties not be able to secure
          such appropriate conversion or adjustment, the Parties shall agree on
          some other index serving the same purpose.

               (b)  Fair Market Value.
                    -----------------

                    (i)   The "fair market value" of the Company's Common Stock
          shall be such value as determined in good faith by the Employee
          Committee established under the Company's 1993 Incentive Stock Option
          Plan, or by any such committee under any successor plan, or in the
          event no such plan or committee is in existence, by an appraiser
          jointly agreed upon by the Company and the Purchaser (or his estate,
          if applicable), or failing such agreement within a reasonable period
          of time, by an independent appraiser appointed by the Company.

                    (ii)  The expenses of any such appraiser contemplated in
          Section 4.4(b)(i) above shall be borne by the Company, except that
          such expenses shall be borne by the Purchaser (or his estate, if
          applicable) in the event that the Stock is repurchased by the Company
          following termination of the Purchaser's employment for good cause in
          accordance with the Company's Employment Agreement with Purchaser
          dated December 4, 1995.

                                       8
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                                   ARTICLE V
                                 Miscellaneous
                                 -------------

          5.1  Notices. Any notice required or permitted under this Agreement
               -------
shall be in writing and may be personally served or sent by facsimile or telex
transmission or mail and shall be deemed to have been given as follows: if
personally served, when served; if by facsimile transmission, when the
transmission is completed to the proper telefax number and confirmation of
receipt of the telefax is received; if by telex transmission, when the
transmission is completed to the proper telex number and confirmation of
delivery of the telex is received; or if mailed, on the fifth business day after
deposit in the mail with airmail postage prepaid and properly addressed. The
Parties shall promptly inform one another of any change in their addresses. For
purposes hereof, the addresses of the Parties (until notice of a change thereof
is given as provided herein) shall be as follows:

          To the Company:

                    MIL 3 Incorporated
                    3400 International Drive, NW
                    Washington, DC 20008
                    Attn: Marc Cohen
                    Telephone: (202) 364-8390
                    Facsimile: (202) 364-8554

          with a copy to:

                    Verner, Liipfert, Bernhard, McPherson and Hand
                    901 15th Street, N.W.
                    Washington, DC 20005
                    Attn: Harold I. Freilich
                    Telephone: (202) 371-6242
                    Facsimile: (202) 371-6279

          To the Purchaser:

                    George M. Cathey
                    2602 Tunlaw Road, N.W.
                    No. 4
                    Washington, D.C. 20007
                    Telephone: 202-338-7213
                    Facsimile: ____________

          5.2  Entire Agreement.  This Agreement sets forth the entire
               ----------------
understanding between the Parties with respect to the subject matter hereof, and
all prior discussions, memoranda

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of understanding, protocols of intent, letters of intent, term sheets and
similar writings with regard hereto, are superseded and hereby terminated.

          5.3  Amendments.  All amendments, deletions and additions to this
               ----------
Agreement shall be in writing, signed by duly authorized representatives of the
Parties.

          5.4  No Waiver of Rights.  No failure or delay by a party in the
               -------------------
exercise of any power, right or privilege hereunder shall operate as a waiver
thereof.  The partial or single exercise by a party of any power, right or
privilege shall not preclude the further or later exercise of that, or any
other, power, right or privilege.

          5.5  Severability.  If any one or more provisions in this Agreement,
               ------------
other than provisions constituting a material consideration to a party, shall be
invalid or unenforceable in any respect under any applicable law, the validity,
legality and enforceability of the remainder of this Agreement shall not be
affected or impaired; provided, however, in such event the Parties shall use
                      --------  -------
their reasonable best efforts to achieve the purpose of the invalid or
unenforceable provision by a new legally valid stipulation.

          5.6  Third Parties.  None of the provisions of this Agreement shall be
               -------------
for the benefit of or enforceable by any third parties except to the extent
expressly set forth herein as to Purchaser's estate.

          5.7  Headings.  The inserted headings are for convenience only and
               --------
shall not be used to construe or interpret this Agreement.

          5.8  Counterparts.  This Agreement may be executed in one or two
               ------------
counterparts, each of which shall be deemed an original, but both of which
together shall constitute one and the same instrument.

          5.9  Binding Effect.  This Agreement shall be binding on the Parties
               --------------
and their legal successors and permitted assignees.

          5.10 Remedies.  Each of the Parties will be entitled to enforce its
               --------
rights under this Agreement specifically, to recover damages by reason of any
breach of any provision of this Agreement and to exercise all other rights
existing in its favor. The Parties agree and acknowledge that money damages may
not be an adequate remedy for any breach of the provisions of this Agreement and
that either party may in its sole discretion apply to any court of law or equity
of competent jurisdiction for specific performance and/or injunctive relief in
order to enforce or prevent any violations of the provisions of this Agreement.

          5.11 Choice of Law. All questions arising under this Agreement shall
               -------------
 be governed by the laws of the District of Columbia (other than its choice of
 law principles).

                           [Signatures on Next Page]

                                      10
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          IN WITNESS WHEREOF, the Parties have executed this Agreement on the
day and year first above written.

                                   MIL 3 INCORPORATED,
                                   a Delaware corporation

                                   By: /s/ Marc A. Cohen
                                       -----------------------
                                       Name:  Marc A. Cohen
                                       Title: Chairman of the Board

                                       /s/ George M. Cathey
                                       -----------------------
                                       George M. Cathey

                                       11
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                              FIRST AMENDMENT TO
                      STOCK PURCHASE AND OPTION AGREEMENT

     This First Amendment (the "Amendment") is made as of this 20th day of
January, 2000, by and among MIL 3, Incorporated, a Delaware corporation (the
"Company"), and George M. Cathey (the "Purchaser").

                                  WITNESSETH:

     WHEREAS, the Purchaser and the Company entered into a Stock Purchase and
Option Agreement dated as of December 4, 1995 (the "Agreement); and

     WHEREAS, the Purchaser and the Company desire to amend the Agreement to
accelerate the vesting of the stock option set forth therein and to make other
modifications;

     NOW, THEREFORE, in consideration of the foregoing and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

     1.   The Agreement shall be amended as follows:

          (a)  The second sentence of Section 1.2(a) of the Agreement, including
clauses (i), (ii) and (iii) thereof, shall be deleted in its entirety and the
following shall be inserted in lieu thereof:

     "The Option may only be exercised during the period commencing on January
     20, 2000 and ending on the first to occur of the following events, and if
     not exercised during such period shall immediately terminate and become
     null and void (such period during which the Option may be exercised is
     hereafter referred to as the "Option Term"):

          (i)   sixty days after notice by the Company to the Purchaser of a
     merger or other business combination involving the Company;

          (ii)  sixty days after notice by the Company to the Purchaser of
     the scheduled effectiveness of the Company's Initial Public Offering (as
     defined below); or

          (iii) December 4, 2006."

          (b)   Section 4.2 shall be deleted in its entirety and the
following shall be inserted in lieu thereof:

"4.2            [Intentionally Deleted]"

          (c)   Section 4.3 shall be deleted in its entirety and the
following shall be inserted in lieu thereof:

"4.3            [Intentionally Deleted]"

                                       1
<PAGE>

          (d)  Section 4.4 shall be deleted in its entirety and the following
shall be inserted in lieu thereof:

"4.4           [Intentionally Deleted]"

          (e)  Section 5.1 shall be amended by deleting the name and address of
Verner, Liipfert, et. al. below the caption "with a copy to:" and substituting
in its place the following:

               "Hale and Dorr LLP
               1455 Pennsylvania Avenue, NW
               Washington, D.C.  20004
               Attn:  Brent B. Siler
               Telephone: (202) 942-8400
               Facsimile: (202) 942-8484"

     2.   As modified hereby, the Agreement is hereby confirmed by both parties
to be in full force and effect.

     3.   This Amendment may be executed in one or more counterparts, each of
which shall be deemed an original, and both of which together shall constitute
one and the same instrument.

     IN WITNESS WHEREOF, the parties have executed this Amendment as of the date
first written above.

                                          MIL 3, INCORPORATED

                                          By: /s/ Marc A. Cohen
                                              ---------------------------
                                              Name: Marc A. Cohen
                                              Title:   Chairman

                                          /s/ George M. Cathey
                                          --------------------------------
                                          George M. Cathey

                                       2<PAGE>

                                                                   EXHIBIT 10.14

                              EMPLOYMENT AGREEMENT

     THIS EMPLOYMENT AGREEMENT (the "Agreement") is entered into as of this
4th day of December, 1995, by and between MIL 3, INCORPORATED (the "Company"),
a Delaware corporation, and GEORGE M. CATHEY (the "Employee"), an individual
residing in Washington, D.C. The Company and Employee are sometimes collectively
referred to herein as the "Parties" and each individually as the "Party."

                                  WITNESSETH:

     WHEREAS, the Company and Employee desire to enter into this Agreement to
provide for the terms and conditions of Employee's employment as a principal
engineer and project manager of the Company.

     NOW THEREFORE, in consideration of the foregoing and other good and
valuable consideration, the Parties hereto agree as follows:

                                   ARTICLE I
                       TERMS AND CONDITIONS OF EMPLOYMENT

     1.1  Engagement.  Subject to the terms and conditions set forth in this
          ----------
Agreement, the Company hereby engages Employee as a principal engineer and
project manager of the Company, and Employee agrees to serve the Company in such
capacity, for a term of six (6) years commencing on the date hereof, unless
Employee sooner resigns, retires, dies, is permanently disabled, or the
Agreement is terminated as hereinafter provided.

     1.2  Services.
          ---------

          (a)  Employee will perform those management and technical duties as a
principal engineer and project manager of the Company as are assigned to him
from time to time by the Company's senior management.

          (b)  Employee will devote his best efforts and substantially all of
his business time and attention (except for reasonable vacation periods and
periods of illness or other incapacity) to the faithful and diligent performance
of his duties hereunder, as required by the business of the Company (and its
subsidiaries and affiliates).
<PAGE>

     1.3  Salary.  So long as Employee is employed by the Company in accordance
          ------
with this Agreement, the Company will pay Employee an annual salary of
$100,000.00 subject to periodic increases at the discretion of the Company's
President, Executive Vice President or other authorized officer, such salary to
be payable in accordance with the Company's general payroll practices.

     1.4  Benefits.  During the term of this Agreement, Employee shall be
          --------
entitled to receive from the Company and participate in all of its customary
health, pension, vacation, bonus and other fringe benefits provided to other
similarly situated employees of the Company.

     1.5  Expenses.  In addition to salary and any other compensation received
          --------
under Sections 1.3 or 1.4, the Company shall promptly reimburse the Employee for
all reasonable travel, entertainment and miscellaneous expenses incurred by
Employee in connection with the performance of his duties under this Agreement
in proper pursuit of the Company's business, provided that the Employee properly
accounts for such expenses to the Company in accordance with the Company's
regular policies.

     1.6  Covenant Not to Compete.
          -----------------------

          (a)  In consideration of the employment, salary and other benefits
provided to Employee under this Agreement, Employee agrees that, while Employee
is employed by the Company under this Agreement and for a period of eighteen
(18) months thereafter, he will not be involved in direct competition with the
Company, except with the express written consent of the Company; specifically,
Employee will not, either directly or indirectly, for himself or on behalf of or
in conjunction with any other person, partnership, corporation or other entity,
own, maintain, engage in, render any services for, manage, have any financial
interest in, permit his name to be used in or hire or solicit any employees or
customers of the Company or its affiliates (as defined below) or subsidiaries
(as defined below) in connection with, any of the Company's products in any
market served by the Company or any subsidiary or affiliate of the Company in
the United States or any market in which the Company or its subsidiaries or
affiliates are engaged in or have, as of the date of the termination of
Employee's employment, firm plans to enter within two years after the date that
Employee's employment hereunder is terminated. The Company shall, within sixty
(60) days from the date of receipt of a written request from Employee, respond
as to whether or not the Company has firm plans to enter a specified market
within such two year period. Notwithstanding the foregoing, Employee may during
such eighteen (18) month period own up to one percent (1%) of the outstanding
voting securities of any publicly-held company.

          (b)  If, at the time of enforcement of any provision of Section 1.6(a)
above, a court holds that the restrictions stated therein are unreasonable under
circumstances then existing, the Parties hereto agree that the maximum period,
scope or geographical area reasonable under such circumstances will be
substituted for the stated period, scope or area.

          (c)  In the event of a breach by Employee of the provisions of Section
1.6(a) above, the Company or its successors or assigns may, in addition to other
rights and remedies existing in their favor, apply to any court of competent
jurisdiction for specific performance

                                       2
<PAGE>

and/or injunctive or other relief in order to enforce or prevent any violations
of the provisions thereof.

          (d)  As used herein, the term "affiliate" means, with respect to any
person or entity, (i) any other person or entity that is directly or indirectly
controlled by, under common control with or controlling such person or entity;
(ii) any other person or entity owning beneficially or controlling five percent
(5%) or more of the equity interest in such person or entity; (iii) any officer,
director or partner of such person or entity; or (iv) any spouse or relative of
such person. As used herein, the term "control" means possession, directly or
indirectly, of the power to direct or cause the direction of the management and
policies of a person or entity, whether through the ownership of partnership
interests or voting securities, by contract or otherwise.

          (e)  As used herein, the term "subsidiary" means, as to any person or
entity, any other entity more than 50% of whose outstanding equity or voting
interests are owned, directly or indirectly, by such person or entity.

     1.7  Confidential Information.  Employee acknowledges that his Agreement
          ------------------------
Regarding Creative Works, Inventions and Confidentiality (the "Confidentiality
Agreement"), dated April 8, 1991, with the Company remains binding on him and in
full force and effect and is additional consideration from him to the Company
for his employment hereunder.

                                  ARTICLE II
                           TERMINATION OF AGREEMENT

     2.1  Termination by the Company for Good Cause.  Employee's employment
          -----------------------------------------
under this Agreement may be terminated by the Company for "good cause," defined
as follows:

          (a)  Employee's habitually willful or negligent failure to perform the
duties that he is required to perform under the terms of this Agreement or as
directed by the senior management of the Company;

          (b)  Employee's habitually willful violation of the reasonable and
substantial rules governing employee performance generally as fixed from time to
time by the senior management of the Company;

          (c)  Employee's habitual refusal to obey reasonable directions from
the senior management of the Company in a manner that amounts to willful or
negligent insubordination;

          (d)  Employee's commission of any act or acts of demonstrable
dishonesty resulting in a material detriment to the Company, or any breach of
the Confidentiality Agreement;

          (e)  Employee's conviction of a felony or other crime involving
dishonesty or moral turpitude;

                                       3
<PAGE>

          (f)  Employee's inability to perform his normal duties for the Company
by reason of illness, injury or incapacity for a period of one hundred twenty
(120) substantially consecutive days;

          (g)  Employee's breach of any provision of this Agreement; or

          (h)  Employee's death or retirement.

     If the Company determines that any of the events or circumstances specified
above as constituting good cause for termination has occurred, the Company may
serve a written notice upon Employee specifying such events or circumstances in
detail and describing the Company's plans with respect thereto. Thereafter,
Employee shall have a period of not less than thirty (30) days in which to cure
any alleged deficiencies in the performance of his obligations under this
Agreement which are specified in the written notice. If, after such written
notice and opportunity to cure, the Company, in good faith, makes a
determination that good cause still exists for the termination of this
Agreement, then the employment of Employee under this Agreement shall be
terminable by the Company upon delivery of a subsequent written notice to
Employee specifying the effective date of termination (which shall in no event
be earlier than the date immediately following the expiration of the thirty (30)
day cure period specified above).

     2.2  Termination by the Employee.  The Employee may terminate this
          ---------------------------
Agreement at any time, by giving (a) thirty (30) days written notice of such
termination to the Company if such notice is given within ten (10) days of any
salary decrease, or (b) ninety (90) days written notice of such termination to
the Company in all other events. The Employee shall have no right to receive
salary, compensation or other benefits for any period after the date of
termination, except as required by law.

     2.3  Effect of Termination.  Upon the termination of this Agreement, the
          ---------------------
rights of Employee or the Company which have accrued prior to the effective date
of such termination shall not be abridged, in whole or in part, or otherwise
adversely affected in any way.

                                  ARTICLE III
                              GENERAL PROVISIONS

     3.1  Notices.  Any notice provided for in this Agreement must be in writing
          -------
and must be delivered to the recipient at the address below indicated:

     To the Company:

          MIL 3, Incorporated
          3400 International Drive
          Washington, D.C. 20008
          Tel. No.: (202) 364-8390
          Fax No.:  (202) 364-8554
          Attn: Marc Cohen, Executive Vice President

                                       4
<PAGE>

     With a copy to:

          Verner, Liipfert, Bernhard, McPherson and Hand
          901 15/th/ Street, N.W.
          Washington, D.C. 20005
          Tel. No.: (202) 371-6242
          Fax No. (202) 371-6279
          Attn: Harold I. Freilich, Esq.

     To Employee:

          George M. Cathey
          2602 Tunlaw Road, N.W.
          No. 4
          Washington, D.C. 20007
          Tel. No.: 202-338-7213
          Fax No.: _______________________

or such other address or to the attention of such other person as the recipient
Party shall have specified by prior written notice to the sending party.  Any
notice under this Agreement will be deemed to have been given five (5) business
days after mailing by first class mail, certified return receipt requested, one
(1) business day after delivery to a receipted courier for next business day
delivery, or upon transmission by telex or facsimile.

     3.2  Severability.  Whenever possible, each provision of this Agreement
          ------------
will be interpreted in such manner as to be effective and valid under applicable
law, but if any provision of this Agreement is held to be invalid, illegal or
unenforceable in any respect under any applicable law or rule in any
jurisdiction, such invalidity, illegality or unenforceability will not affect
any other provision or any other jurisdiction, but this Agreement will be
reformed, construed and enforced in such jurisdiction as if such invalid,
illegal or unenforceable provision had never been contained herein.

     3.3  Complete Agreement.  This Agreement and those documents expressly
          ------------------
referred to herein embody the complete agreement and understanding between the
Parties and supersede and preempt any prior understandings, agreements
(including any employment agreements) or representations by or between the
Parties, written or oral, which may have related to the subject matter hereof in
any way, provided, however, that this Agreement shall not supersede or preempt
         --------  -------
any agreements between the Company and the Employee relating to the Company's
1993 Incentive Stock Option Plan.

     3.4  Counterparts.  This Agreement may be executed on separate
          ------------
counterparts, each of which is deemed to be an original and both of which taken
together constitute one and the same agreement. This Agreement may be executed
and delivered by facsimile transmission.

     3.5  Successors and Assigns.  This Agreement is intended to bind and
          ----------------------
inure to the benefit of and be enforceable by Employee and the Company, and each
of their respective

                                       5
<PAGE>

successors and assigns, except that Employee may not assign any of his rights or
obligations under Article I.

     3.6  Choice of Law.  All questions concerning the construction, validity
          -------------
and interpretation of this Agreement will be governed by the internal law, and
not the law of conflicts, of the District of Columbia.

     3.7  Remedies.  Except as provided in Section 3.9, each of the Parties
          --------
will be entitled to enforce its rights under this Agreement specifically, to
recover damages by reason of any provision of this Agreement and to exercise all
other rights existing in its favor. The Parties agree and acknowledge that money
damages may not be an adequate remedy for any breach of the provisions of this
Agreement and that any Party may in its sole discretion apply to any court of
law or equity of competent jurisdiction for specific performance and/or
injunctive relief in order to enforce or prevent any violations of the
provisions of this Agreement. The prevailing Party in any action described in
this Section 3.7 shall be entitled to payment of its reasonable attorneys' fees
from the other Party.

     3.8  Amendments and Waivers.  Any provision of this Agreement may be
          ----------------------
amended or waived only with the prior written consent of the Company and
Employee.

     3.9  Arbitration.  Any dispute or controversy arising out of this
          -----------
Agreement, other than such dispute or controversy concerning the Confidentiality
Agreement and/or Section 1.6, shall be determined by arbitration before an
arbitrator acceptable to the Parties. If no mutually acceptable arbitrator can
be found, each Party shall select one arbitrator, the two arbitrators so chosen
shall select a third arbitrator, and the decision of a majority of such
arbitrators shall be binding and conclusive on all Parties. Such arbitration
shall take place in Washington, D.C. in accordance with rules and procedures of
the American Arbitration Association then in effect. The judgment on any award
made by the arbitrators may be entered in any court having jurisdiction thereof,
Each party shall bear its own expenses (including the expenses and fees of the
arbitrator it selects and one-half of the fees and expenses of the third
arbitrator contemplated above) in connection with such arbitration, judgement
and enforcement, provided, however, that the filing and similar costs of
                 --------  -------
convening and conducting the arbitration shall be borne equally by the Parties.

     3.10 Survival.  Notwithstanding anything to the contrary herein, the
          --------
provisions of Section 1.6 and of the Confidentiality Agreement shall survive any
termination of the Agreement.

                                       6
<PAGE>

     IN WITNESS WHEREOF, the Parties have executed this Agreement on the day
and year first above written.

                                    MIL 3 INCORPORATED,
                                    a Delaware corporation

                                    By: /s/ Marc A. Cohen
                                        ----------------------------
                                        Marc A. Cohen
                                        Chairman of the Board

                                    /s/ George M. Cathey
                                    --------------------------------
                                    George M. Cathey

                                       7

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