<PAGE>
                                                                   EXHIBIT 10.21


                 ALION MEZZANINE DEFERRED COMPENSATION AGREEMENT





        This deferred compensation agreement ("the Agreement"), effective
December 20, 2002 by and between Alion Science and Technology Corporation, a
Delaware corporation ("Alion") and Bahman Atefi ("Participant") is intended to
establish a plan of nonqualified deferred compensation in order to provide
Participant with a degree of retirement income security and to encourage
Participant to provide continued services to Alion.


                                   WITNESSETH:


WHEREAS, Participant is a member of a select group of management and highly
compensated employees of Alion; and

WHEREAS, it is the intent of the parties to have this Agreement be a plan of
nonqualified deferred compensation within the meaning of the Internal Revenue
Code of 1986, as amended;

NOW, THEREFORE, Alion and the Participant hereby agree that the following shall
be the terms, provisions, conditions and covenants of this Agreement, effective
December 20, 2002.

1.  PURPOSE OF AGREEMENT. The Agreement shall serve as a nonqualified deferred
    compensation plan to benefit the Participant.

2.  PARTICIPANT. The sole Participant of this Agreement shall be Bahman Atefi,
    who shall become a Participant upon execution of this Agreement.

3.  PLAN ADMINISTRATOR. That person or persons designated from time to time by
    the Board of Directors of Alion ("the Board").

4.  DEFERRED COMPENSATION ACCOUNT. Alion shall credit to a book reserve (the
    "Deferred Compensation Account") established for this purpose, $856,564.63
    on December 20, 2002.

5.  PLAN YEAR. Each respective twelve-month period commencing on the effective
    date of this Agreement, and ending on the one-year anniversary thereafter.

<PAGE>

6.  CREDITING OF EARNINGS FOR DEFERRED COMPENSATION ACCOUNT. The Participant's
    Deferred Compensation Account shall be credited quarterly by the Plan
    Administrator based on a fixed twelve percent (12%) annual rate of notional
    interest as though: (i) Participant's Deferred Compensation Account were
    invested in a fixed interest bearing investment account, provided that Alion
    has made the corresponding interest payment required as of such date under
    the Senior Subordinated Note (the "Mezzanine Note(s)") issued by Alion to
    the holder(s) thereof and if not, when Alion makes such payment; and (ii)
    any distribution made to the Participant that decreases the Participant's
    Deferred Compensation Account ceased being invested in this interest bearing
    account as soon as administratively possible.

    The Participant may make an irrevocable election 180 days prior to the
    commencement of each Plan Year to either receive current compensation equal
    to the interest so determined as it is earned in the applicable Plan Year,
    or to instead receive interest credits to his Deferred Compensation Account
    in amounts equal to this stated interest rate. Such election shall be
    irrevocable with respect to that Plan Year. If Participant makes such an
    election to receive current compensation equal to the interest, such
    payments shall be conditioned on Alion making the corresponding interest
    payment required as of such date under the Mezzanine Note(s) issued by Alion
    to the holder(s) thereof and if not, when Alion makes such payment. If
    Participant makes no election for a Plan Year then the notional interest
    shall be credited to his Deferred Compensation Account as described above.
    For the initial Plan Year, this election must be made in writing by
    Participant prior to the effective date of this Agreement.

    If Alion terminates Participant's employment for Just Cause (as defined by
    Section 11.a of Participant's Employment Agreement) or if Participant
    terminates his employment with Alion without Good Reason (as defined by
    Section 15.a but for this purpose only, without regard to whether the
    occurrence of one of the events is during the Protection Period, as defined
    by the Employment Agreement), then regardless of any such election by
    Participant, no current payments of interest as compensation shall be made
    available and all such interest shall instead be credited quarterly to
    Participant's Deferred Compensation Account as described in this Section 6.

7.  INVESTMENT OF DEFERRED COMPENSATION ACCOUNT. Any amount credited to the
    Deferred Compensation Account may be kept in cash or invested and reinvested
    by Alion in mutual funds, stocks, bonds, securities or any other assets as
    may be selected by the Board in its discretion in order to satisfy the
    obligation to Participant. In the exercise of the foregoing discretionary
    investment powers, the Board may engage investment counsel and, if it so
    desires, may delegate to such counsel full or limited authority to select
    the assets in which the funds are to be invested.

8.  CREATION OF A TRUST. The Board, in its sole discretion, may establish a
    trust that shall remain subject to the claims of Alion's creditors. Upon
    creation of such trust, Alion shall contribute to the trust an amount equal
    to the amount credited to the Participant's Deferred

<PAGE>

    Compensation Account. The investment of trust assets shall be performed in
    accordance with Section 7 of this Agreement.

9.  NO RIGHTS IN DEFERRED COMPENSATION ACCOUNT OR TRUST. In the event that Alion
    or the trustee (as that term is defined in the trust), in its own
    discretion, decides to invest the amounts recorded in the Deferred
    Compensation Account or contributed to the trust, Participant shall have no
    rights in or to such investments themselves. Without limiting the foregoing,
    the Participant's Deferred Compensation Account shall at all times be a
    bookkeeping entry only and shall not represent any investment made on his
    behalf by Alion or the trust and the Participant shall at all times remain
    an unsecured creditor of Alion.

10. PAYMENT OF DEFERRED COMPENSATION. Participant shall receive one hundred
    percent (100%) of his Deferred Compensation Account within thirty (30) days
    of the later of the Plan Year ended December 20, 2008 or the date the
    holders of the Mezzanine Note(s) have been paid in full the principal of
    their Mezzanine Note(s), and any accrued but unpaid interest thereon.

11. REPORTING. From time to time, not less often than quarterly, the Plan
    Administrator shall provide to Participant an accounting of assets, income,
    gain and loss in the Participant's Deferred Compensation Account. Unless
    waived by the Participant, upon termination of the Deferred Compensation
    Account, the Plan Administrator shall make an accounting available to
    Participant.

12. NONALIENATION OF BENEFITS. The right of the Participant or any other person
    to the payment of deferred compensation or other benefits under this
    Agreement shall not be assigned, transferred, pledged or encumbered except
    by will or by the laws of descent and distribution.

13. WITHHOLDING. Alion, or the trustee of the trust, shall withhold from any
    distributions made to Participant under this Agreement all federal, state
    and local income, employment and other taxes required to be withheld by
    Alion, or the trustee of the trust, in connection with such distributions,
    in amounts and in a manner to be determined in the sole discretion of Alion
    and the trustee of the trust.

14. NO RIGHTS TO CONTINUED EMPLOYMENT. Nothing contained herein shall be
    construed as conferring upon the Participant the right to continue in the
    employ of Alion as an executive or in any other capacity.

15. DEFERRED COMPENSATION NOT BENEFIT BEARING. Any deferred compensation payable
    under this Agreement shall not be deemed salary or other compensation to the
    Participant for the


<PAGE>

    purpose of computing benefits to which he may be entitled under any pension
    plan or other arrangement of Alion for the benefit of its employees.

16. INTERPRETATION OF AGREEMENT. The Board shall have full power and authority
    to interpret, construe, and administer this Agreement and the Board's
    interpretations and construction thereof, and actions thereunder, including
    any valuation of the Deferred Compensation Account, or the amount or
    recipient of the payment to be made therefrom, shall be binding and
    conclusive on all persons for all purposes. No member of the Board shall be
    liable to any person for any action taken or omitted in connection with the
    interpretation and administration of this Agreement unless attributable to
    his or her own willful misconduct or lack of good faith.

17. AGREEMENT BINDING ON SUCCESSORS. This agreement shall be binding upon and
    inure to the benefit of Alion, its successors and assigns, and the
    Participant and his heirs, executors, administrators, and legal
    representatives.

18. WARRANT AGREEMENT. Participant has received a grant of warrants equal to
    0.525% of Alion's common stock on the closing date of the acquisition on a
    fully diluted basis (assuming the exercise of all outstanding warrants).
    These warrants have been granted under a separate agreement between Alion
    and Participant, and such warrant agreement is not affected by this
    Agreement.

19. GOVERNING LAW. This Agreement shall be construed in accordance with and
    governed by the laws of the Commonwealth of Virginia.

20. SEVERABILITY. If any provision of this Agreement is found, held or deemed to
    be void, unlawful or unenforceable under any applicable statute or other
    controlling law, the remainder of this Agreement shall continue in full
    force and effect.

<PAGE>

In WITNESS WHEREOF, Alion has caused this Agreement to be executed by its duly
authorized officers and Participant has hereunto set his hand and seal as of the
date first above written.

Dr. Bahman Atefi, Participant      Alion Science and Technology Corporation,
                                   a Delaware Corporation




                                   By:
---------------------------------     ---------------------------------


                                   ------------------------------------
                                   Title