Document:

<PAGE>

                                                                   EXHIBIT 10.10

                       MANTECH INTERNATIONAL CORPORATION
                       ---------------------------------

                     SUPPLEMENTAL EXECUTIVE RETIREMENT PLAN
                     --------------------------------------
                           (F/B/O John A Moore, Jr.)

                                    ARTICLE I

                                    Preamble

1.1  Purpose. ManTech International Corporation (the "Company") hereby
     -------
     establishes the ManTech International Corporation Supplemental Executive
     Retirement Plan (F/B/O John A. Moore, Jr.) (the "SERP"). The Company has
     adopted the SERP in recognition of the contributions which John A. Moore,
     Jr. (the "Member") has made and continues to make toward the success,
     growth, and development of the Company. The SERP will allow the Member to
     defer a portion of his current compensation until future years.

1.2  Effective Date. The SERP shall be effective as of April 12, 1996.
     --------------

                                   ARTICLE II

                                  Definitions

2.1  Definitions. Where the following words and phrases appear and are
     -----------
     capitalized in the SERP, they shall have the respective meanings set forth
     below:

     (a) Beneficiary. The person or persons designated by the Member to receive
         -----------
         Preretirement Death Benefits or payments of Deferred Compensation upon
         the Member's death or incapacitating Disability.

     (b) Board. The Board of Directors of ManTech International Corporation.
         -----

     (c) Code. The Internal Revenue Code of 1986, as amended and as it may be
         ----
         from time to time be further amended or supplemented.

     (d) Committee. The initial committee shall consist of John A. Moore, Jr.,
         ---------
         Walter W. Vaughan and Michael D. Golden, directors of the Corporation.
         The Board may substitute or appoint other individuals as members of the
         committee to administer the SERP.

<PAGE>

        (e)     Company. ManTech International Corporation and any of its
                -------
                affiliates and subsidiaries.

        (f)     Compensation. The total annual remuneration earned by the Member
                ------------
                including consulting fees, bonuses, incentive compensation,
                contributions made by the Company to a qualified plan under a
                salary reduction or similar arrangement and any amounts deferred
                by the Member pursuant to a non-qualified plan (including
                amounts deferred pursuant to Article VII of the SERP).

        (g)     Deferred Retirement. The first day of any month subsequent to
                -------------------
                the Member's Normal Retirement Date.

        (h)     Disability. A physical or mental condition for which the Member
                ----------
                shall be eligible to receive benefits under the disability
                insurance provisions of the Social Security Act.

        (i)     Disability Retirement Date. The first day of the month
                --------------------------
                coincident with or next following the date which the Member is
                deemed to have incurred a Disability.

        (j)     Member. John A. Moore, Jr.
                ------

        (k)     Death Benefits. The benefits payable upon the death of the
                --------------
                Member, calculated according to Article VI.

        (l)     Retirement. The date on which the Member terminates his service
                ----------
                with or for the Company as an employee and/or consultant.

        (m)     SERP Benefits. The benefits payable upon the Retirement or
                -------------
                Disability of the Member, calculated according to Article V.

                                  ARTICLE III

                                     Member

3.1     Member. John A. Moore, Jr. shall be the sole Member in the SERP.
        ------

                                   ARTICLE IV

                         Eligibility for SERP Benefits

4.1     Retirement. The Member shall be eligible to receive SERP Benefits upon
        ----------
        Retirement.

                                      -2-

<PAGE>

4.2     Death. In the event of the Member's death prior to the commencement of
        -----
        SERP Benefits, the Member's designated beneficiary shall be entitled to
        receive a Preretirement Death Benefit (determined in accordance with
        Article VI).

4.3     Disability. The Member shall be eligible to receive SERP Benefits if
        ----------
        the Member is eligible to receive disability benefits under the Pension
        Plan.

4.4     Vesting. The Member, having completed ten years of service with the
        -------
        Company, shall be immediately fully-vested in all the benefits provided
        for hereunder.

                                   ARTICLE V

                        SERP Contributions and Benefits

5.1     Amount of SERP Contributions. The Company shall contribute the following
        ----------------------------
        amounts to the SERP:

        (a)     $25,000 with respect to the calendar year 1995;

        (b)     $25,000 with respect to the calendar year 1996; and

        (c)     thereafter such benefits as the Company may determine in its
                sole discretion, and the Company shall pay (in addition to such
                contributions) all costs, fees, expenses and taxes (except the
                taxes of the Member or the Beneficiary resulting from a
                distribution of benefits hereunder) arising out of the
                administration of the Trust or investment of the Trust assets.

5.2     Amounts of SERP Benefits. The Member's SERP benefit shall consist of all
        ------------------------
        amounts required to be contributed to the SERP, as provided in Section
        5.1 above, plus all interest and other earnings accrued thereon.

5.3     Form of SERP Benefit. The SERP benefit shall be paid to the Member in
        --------------------
        the form of a lump-sum cash payment, or in periodic installment payments
        as specified by the Member in a written request made prior to the
        Member's Retirement.

5.4     Payment of SERP Benefits. SERP Benefits shall be paid or commenced as
        ------------------------
        soon as reasonably practicable after the Member becomes eligible to
        receive such benefits.

                                   ARTICLE IV

                          Preretirement Death Benefit

                                      -3-

<PAGE>

6.1     Amount of Preretirement Death Benefit. The amount of a Preretirement
        -------------------------------------
        Death Benefit shall be the amount determined under Section 5.2 of the
        SERP as of the Member's date of death.

6.2     Form of Preretirement Death Benefit. The Preretirement Death Benefit
        -----------------------------------
        shall be paid to a Member's designated Beneficiary in the form of a
        lump-sum cash payment or in periodic installment payments over the term
        designated by the Member prior to the Member's Retirement.

6.3     Payment of Preretirement Death Benefit. Preretirement Death Benefits
        --------------------------------------
        shall be paid (or, in the case of installment payments, commence) as
        soon as reasonably practicable after the date of the Member's death.

                                   ARTICLE VII

                             Deferred Compensation

7.1     Deferred Compensation. The Member may elect to defer any portion of the
        ---------------------
        Member's Compensation that will be earned and payable for services to be
        performed for the Company. Any such election shall be irrevocable and
        shall be made in accordance with the rules prescribed in Section 7.2.

7.2     Election to Defer Compensation.
        ------------------------------

        (a)     Election. At any time prior to his entitlement to Compensation
                --------
                from the Company, the Member may elect to defer all or a portion
                of such Compensation hereunder.

        (b)     Form of Election. The initial and any subsequent elections to
                ----------------
                defer Compensation shall be made on forms prescribed by the
                Board or the Committee. The election forms shall specify the
                amount of Compensation to be deferred (either as a dollar amount
                or as a percentage of Compensation), the future date or dates on
                which the Deferred Compensation will be paid, and the form in
                which the Deferred Compensation will be paid.

7.3     Account.
        -------

        (a)     Establishment of Account. The Company shall establish a separate
                ------------------------
                bookkeeping account for the Member with respect to the Deferred
                Compensation. The account shall be invested in accordance with
                Section 7.3(b) and shall be credited in accordance with Section
                7.3(c).

                                      -4-

<PAGE>

     (b)  Investment of Account. The amount deferred under Section 7.1 may be
          ---------------------
          kept in cash or invested and reinvested in mutual funds, stocks,
          bonds, securities, or any other assets as may be selected by the
          Committee in its discretion. The Committee may delegate full or
          limited authority to select the assets in which the amounts deferred
          under Section 7.1 are to be invested.

     (c)  Credits to Account. The Committee shall credit to the book account
          ------------------
          the actual net pre-tax earnings of the Company from time to time
          accruing on the invested assets.

7.4  Payment of Deferred Compensation.
     --------------------------------

     (a)  Time or Payment. Except as provided in Section 7.4(b), the amount
          ---------------
          credited to the Member's Deferred Compensation account shall be paid
          on the date or dates specified in the Member's Deferred Compensation
          election.

     (b)  Death or Disability. In the event of the Member's death or Disability
          -------------------
          prior to the date or dates specified for payment of the Member's
          Deferred Compensation, the Company shall pay the amounts credited to
          the Member's Deferred Compensation account to the Member or, as
          appropriate, to the Member's designated Beneficiary. Such payment
          shall be made as soon as reasonably practicable after the occurrence
          of the Member's death or Disability.

     (c)  Form of Payment. The amounts credited to the Member's Deferred
          ---------------
          Compensation account shall be paid in the form specified in the
          Member's Deferred Compensation election. In the event of the Member's
          death or Disability, the payment of such amounts may be accelerated in
          such manner as the Company, in its sole discretion, shall determine.

7.5  Member's Interest. The amounts credited to the Member's Deferred
     -----------------
     Compensation account shall remain the sole property of the Company, subject
     to the claims of its general credits, and neither the Member nor his legal
     representative or Beneficiary shall have any right, other than the right of
     an unsecured creditor, against the Company with regard to any portion of
     such Deferred Compensation.

                                  ARTICLE VIII

                                     Trust

8.1  Trust. The Company may establish a Trust for the administration and
     ----
     investment of the funds contributed for the benefit of the Member and to
     satisfy its payment obligations under the SERP. Any assets or property held
     by the Trust shall be subject to the claims of the COmpany's general
     creditors only upon the insolvency or bankruptcy of the

                                      -5-

<PAGE>

      Company, and no person other than the Company shall, by virtue of the
      provisions of the SERP, have any interest in such funds. To the extent
      that any person, including the Member, acquires the right to receive
      payments of SERP Benefits or Deferred Compensation, such right shall be no
      greater than the right of any unsecured general creditor of the Company.

8.2   Administration. The SERP will be administered by the Board or the
      --------------
      Committee. The Board or the Committee shall have absolute discretion to:

      (a) Interpret the SERP;

      (b) Create and revise rules and procedures of the administration of the
          SERP;

      (c) Provide direction and instruction to the Trustee regarding the
          investment and payment of SERP Benefits and Deferred Compensation as
          hereinabove provided; and

      (d) Take any other actions and make any other determinations as it may
          deem necessary and proper for the administration of the SERP. Any
          expenses which are incurred in the administration of the SERP will be
          paid by the Company.

8.3   Investment Directions. The Committee or Board shall respect the written
      ---------------------
      directions of the Member with respect to investment of the SERP assets,
      and will direct the Trustee accordingly, provided the investments are not
      prohibited by applicable fiduciary investment laws. With respect to any
      directed investment, the Member shall hold the Company and Trustee
      harmless for any breach of fiduciary duty with respect to the making of
      such investment.

                                   ARTICLE IX

                           Amendment and Termination

9.1   Amendment and Termination. The Board or Committee retains the right to
      -------------------------
      modify, amend or terminate the SERP; provided, however, that no
      modification, amendment or termination shall adversely affect the rights
      of the Member or his designated Beneficiaries to Deferred Compensation,
      SERP Benefits or Preretirement Death Benefits deferred or accrued before
      such modification, amendment or termination. Notice of every such
      modification, amendment or termination shall be given in writing to the
      Member.

                                   ARTICLE X

                                 Miscellaneous

                                      -6-

<PAGE>

10.1    Non-Guarantee of Employment. Membership in the SERP does not give the
        ---------------------------
        Member any right to be retained in the service of the Company.

10.2    No Assignment. No amounts payable under the SERP shall be subject in any
        -------------
        way to alienation, sale, transfer, assignment, pledge, attachment,
        garnishment, execution, or encumbrance of any kind; any attempt to
        accomplish the same shall be void, except as provided for in Section
        10.3 below.

10.3    Withholding. The Company shall have the right to deduct from any
        -----------
        payments of SERP Benefits or Deferred Compensation the taxes required by
        law to be withheld from the Member or Beneficiary with respect to such
        payments.

10.4    Masculine, Feminine, Singular and Plural. The masculine shall be read in
        ----------------------------------------
        the feminine, the singular in the plural, and vice versa, whenever the
        context shall so require.

10.5    Governing Law. Except to the extent preempted by applicable federal
        -------------
        laws, the SERP shall be construed according to the laws of the
        Commonwealth of Virginia other than its choice of law principles.

                                      -7-<PAGE>
                                                                   Exhibit 10.11

                 [MANAGEMENT TECHNOLOGY LETTERHEAD APPEARS HERE]

 20 November 2000

Mr. Bradley H. Feldmann
c/o Residence Inn by Marriott
100 Maple Road, Room 126
Williamsville, NY 14221

Dear Brad:

This will confirm our offer to you of a regular, full-time position as a Senior
Corporate Vice President of ManTech International Corporation at a rate of
$9,616 bi-weekly commencing December 4, 2000. In addition to your basic salary,
you will be entitle to an annual bonus targeted at $75,000. Further, in certain
circumstances, we will negotiate an incentive bonus plan where you are given the
assignment of turning around an unprofitable organization or significantly
increasing the revenue and/or market share of a given operation. All of these
incentives will be driven by the EBIT produced by the operation not just
increases in sales.

You will report directly to me in my capacity as Chairman of the Board, CEO &
President of ManTech International. In your capacity as Senior Corporate Vice
President, you will join a small team of senior executives who have
responsibility of the strategic direction of the entire corporation worldwide.
We currently operate in 30 countries and 32 states here in the United States.
The vast majority of these operations are operated as subsidiaries of ManTech
International Corporation under the ManTech name but we also operate some
partially-owned subsidiaries such as Praxa Limited in Australia and ManTech U.K.
Systems Corporation in the United Kingdom. You will be required to become
knowledgeable relative to all of these operations.

Initially, your focus will be in developing the Corporate Strategic Plan and
preparing for our Corporate Strategy meetings in January. We believe your
recent Corporate experience is invaluable in reviewing our strategies and
improving them. From an operational point-of-view, we envision that you will
take direct responsibilities for a number of current ManTech subsidiaries or
operating groups (most likely 3.) The President or Senior Executive of these
groups will report to you in your Senior Corporate

<PAGE>

Page 2

Vice President capacity. Your goal will be improve their strategic position in
the marketplace, their marketing plans and to significantly improve their growth
factor.

You will be entitled to participate in ManTech's fringe-benefit program/1/,
which currently includes the following:

        .  Insurance coverages provided at no cost to the employee to include:
           - Basic life and AD&D insurance of 1x annual salary
             - Executive Life/AD&D insurance of 2x annual salary
             - Travel insurance up to 6 times your annual salary, maximum
               payment $1,000,000.00

        .  Optional insurance coverages available on a shared-cost basis:
           - Health Care coverage for employee and family
             - Dental insurance for employee and family
             - Long-term disability insurance

        .  Flexible spending funds under IRS Code Sec. 125; employees may set
           aside a portion of salary for Health and/or Dependent Care
           Reimbursement.

        .  Short-term disability, which provides 100 percent of salary
           continuation up to 23 calendar days per disability, starting on the
           22nd day of continuous disability.

        .  ManTech International Retirement Plan, which is a 401(k),
           tax-deferred individual investment program augmented by company
           matching contributions.

        .  Executive Supplemental Savings Plan, a deferred compensation program
           designed for ManTech executives.

        .  Employee Stock Ownership Plan.

        .  Up to 5 working days of sick absence per year.

        .  Annual vacation, as discussed and agreed upon, up to 4 weeks per
           year.

        .  Nine designated paid holidays per year.

--------------
/1/The company policy manual or benefit summary plan descriptions govern
ManTech's benefits program. These documents are controlling and are subject to
change.

<PAGE>

Page 3

        .  Tuition assistance for management-approved, job related courses.

        .  On a contributory basis:
           - Long Term Care
           - Group Legal Plan
           - Group Universal Life and AD&D coverage is available for employee
             and dependents.
           - Income Protection Insurance for Cancer and/or Hospital Intensive
             Care treatment(s).

As a member of the ManTech International Corporate staff, you will be a
participant in the Corporate bonus plan (we have indicated your targeted bonus
in Paragraph 1 above) in effect at the time Corporate bonuses are awarded which
normally occurs on 1 April of every year.

You will receive a monthly car allowance to be negotiated which is normally
based upon the monthly rental/lease cost plus expenses.

As we agreed, we will relocate you and your family from Buffalo to Northern
Virginia at your convenience. The Corporation will pay for the moving expenses,
real estate fees and closing fees. Financing costs will be considered as agreed
upon prior to the transaction. In the interim, we will make an appropriate
arrangement for living expenses.

ManTech International does not currently have a Stock Option Plan for senior
executives. It has been our policy, when unique business opportunities arise,
such as the setting up of a new corporation that penetrates new markets or
clustering of existing corporate entities to form a new business unit to offer
the senior executive stock interest in such subsidiaries in some case where
unique circumstances exist. To date, we have limited the stock participation to
all executives of such subsidiaries usually 20% of the total equity. This is not
a formal plan but a practice that we have followed for several years. If and
when ManTech International establishes a stock option plan for senior corporate
executives, you will be considered for inclusion in the plan on the same basis
as other executives.

In compliance with Federal law, ManTech employment offers are contingent upon
verification of U.S. Citizenship or of Legal Alien/Work Authorization status.
Attached is an INS Form I-9. Please review this form and note the list of
documents that you may present to prove your identity and right to work in the
U.S. Complete Section 1 of this form and bring it and available identity
documents along with you on the first day you come to work. This is a legal
requirement, which must be fulfilled by all employers and new employees.

<PAGE>

Page 4

The great majority of ManTech's jobs require a security clearance. Your
assignment to any of these jobs may require that you be granted a personal
clearance to the appropriate level. Failure to obtain such a clearance may
preclude continuing assignment.

Employment at ManTech's is "at will." This means that either the company or
the employee is free to end the employment relationship at any time, for any
reason. In the event ManTech elects to terminate your agreement at some point
in the future, we will provide a severance package of 12 months pay plus a
prorata share of your bonus.

Brad, as you know, I look forward to your joining us and ask that you indicate
your acceptance of this offer by executing the block below and returning the
original to us in the enclosed envelope.

                                        Sincerely,

                                        MANTECH INTERNATIONAL CORPORATION

                                        /s/ George J. Pedersen

                                        George J. Pedersen
                                        Chairman of the Board, CEO & President

[X]  accept this offer of employment and authorize the use of my resume by
     ManTech

[ ]  I decline this offer of employment

/s/ BH Feldmann                                              11/20/00
----------------------------------------                     ----------------
Signature                                                    Date

/1/ ManTech's benefit program is governed by the specific provisions described
in the company policy manual or benefit summary plan descriptions. These
documents are controlling and are subject to change.

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00033-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00033-of-00352.parquet"}]]