<PAGE>
                                                              Exhibit 10.20 
                                                              ------------- 

                        EXECUTIVE EMPLOYMENT AGREEMENT
                        ------------------------------

This EMPLOYMENT AGREEMENT is made as of the date hereinafter set forth, in 
Vienna, Virginia, by and between the undersigned employee ("Employee"), and GRC
International, Inc., a Delaware corporation ("Company"). In consideration of the
mutual premises, promises, covenants and agreements herein contained, Employee
and the Company agree as follows:

1. Duties.
   ------

(a) The Company hereby employs Employee in the capacity set forth in Item 1(a)
of Exhibit A attached hereto and made a part hereof. Employee hereby accepts
such employment and agrees to perform the duties of such office(s). Employee's
duties will include all of those generally associated with said position,
subject to the direction and assignment of the Company's Board of Directors. All
of employee's working time and energies shall be devoted to the foregoing
duties. The duties assigned to Employee shall be performed at the place of
employment specified in Item 1(b) of Exhibit A or at such other location as the
Board of Directors may determine is in the best interest of the Company.

(b) This Agreement cancels and replaces in their entirety any and all previous 
employment agreements entered into between Employee and the Company or any of 
its subsidiaries.

2. Term of Employment. The employment relationship provided for herein shall 
   ------------------
commence as of the Effective Date of this Agreement as specified in Exhibit A, 
Item 2, and remain in effect until such time as the Agreement shall be 
terminated pursuant to Section 7 below.

3. Compensation.
   ------------

(a) During the term of Employee's employment hereunder, the Company shall pay 
Employee the annual salary set forth in Exhibit A, Item 3(a) ("Gross Annual 
Salary").

(b) In addition to the Gross Annual Salary, Employee shall be entitled to 
receive the additional compensation, if any, specified in Exhibit A, Item 3(b) 
("Additional Compensation").

(c) Employee shall be entitled to receive such fringe benefits as the Company 
normally confers upon its employees holding similar or equivalent positions.

(d) In the event of Employee's death, this Agreement will be terminated and all 
accrued and unpaid compensation and expenses will be payable to the Employee's 
estate.

(e) If the Company, with or without cause, terminates Employee's employment or 
gives Employee notice of termination, or if the Employee terminates his 
employment or gives notice of termination by reason of a material breach by the 
Company of the terms of this Agreement (including but not limited to the terms 
set forth on Exhibit A hereto), at any time during the twelve-month period 
following a Change of Control (as hereinafter defined), then Employee shall 
receive, in addition to any other compensation provided for in this Agreement, a
lump-sum severance payment in an amount equal to the Gross Annual Salary, less 
any income, excise, employment or other tax holdings which the Company is 
required by law to deduct therefrom.
















<PAGE>
 
(f) For purposes of this Agreement, a Change in Control shall mean the 
satisfaction of the conditions set forth in any one of the following paragraphs:

     (i)   any person (as defined in Section 3(a)(9) of the Securities Exchange 
Act of 1934, as amended (the "Exchange Act") as modified and used in Sections 
13(d) and 14(d) thereof, except that neither (A) the Company or any of its 
                         ------
subsidiaries, (B) a trustee or other fiduciary holding securities under an 
employee benefit plan of the Company or any of its subsidiaries, (C) an 
underwriter temporarily holding securities pursuant to an offering of such 
securities, nor (D) a corporation owned, directly or indirectly, by the 
stockholders of the Company in substantially the same proportions as their 
ownership of stock of the Company shall be included in such term) (a "Person") 
is or becomes the "beneficial owner" (as defined in Rule 13d-3 under the 
Exchange Act), directly or indirectly, of securities of the Company (not 
including in the securities beneficially owned by such Person any securities 
acquired directly from the Company or its affiliates) representing 25% or more 
of the combined voting power of the Company's then outstanding securities; or 

     (ii)  during any period of up to two consecutive years (not including any
period prior to the execution of this Agreement, individuals who at the
beginning of such period constitute the Board of Directors of the Company
(the "Board") and any new director (other than a director designated by a Person
who has entered into an agreement with the Company to effect a transaction
described in clause (i), (iii) or (iv) of this paragraph) whose election by the
Board or nomination for election by the Company's stockholders was approved by a
vote of at least two thirds (2/3) of the directors then still in office who
either were directors at the beginning of the period or whose election or
nomination for election was previously so approved, cease for any reason to
constitute a majority thereof; or

     (iii) the shareholders of the Company approve a merger or consolidation of
the Company with any other corporation, other than (A) a merger or consolidation
which would result in the voting securities of the Company outstanding
immediately prior thereto continuing to represent (either by remaining
outstanding or by being converted into voting securities of the surviving
entity), in combination with the ownership of any trustee or other fiduciary
holding securities under an employee benefit plan of the Company, at least 75%
of the combined voting power of the voting securities of the Company or such
surviving entity outstanding immediately after such merger or consolidation, or
(B) a merger or consolidation effected to implement a recapitalization of the
Company (or similar transaction) in which no Person acquires more than 50% of
the combined voting power of the Company's then outstanding securities; or

     (iv)  the shareholders of the Company approve a plan of complete
liquidation of the Company or an agreement for the sale or disposition by the
Company of all or substantially all the Company's assets.

4. Competition.
   -----------

(a) Until termination or expiration of this Employment Agreement, absent the
expressed, prior written authorization of the Company's Board of Directors,
Employee shall not, directly or indirectly, engage in any activity competitive
with or adverse to the Company's business or welfare, whether alone, as a
partner of any partnership or joint venture or as an officer, director,
employee, or holder of 5% or more of any class of stock, of any corporation.

                                      2 










































































<PAGE>
 
(b) Employee acknowledges and agrees that the Company's telecommunications 
business (i) markets the OSU(TM) Network Interface and its derivatives, products
which provide performance monitoring, alarm surveillance, overhead byte 
modification and translation, interoperability between otherwise incompatible 
systems, network isolation and security, network test access, and/or numerous 
other functions, (ii) provides custom telecommunications software, and (iii) 
produces network analysis software (collectively, the foregoing businesses 
described in (i), (ii) and (iii) are hereinafter referred to as the 
"Telecommunications Business"). During employment and for a period of eighteen 
(18) months after the termination of employment, absent the expressed, prior 
written authorization of the Company's Board of Directors, Employee shall not,
directly or indirectly, whether alone, as a partner of any partnership or joint
venture or as an officer, director, employee, or holder of 5% or more of any
class of stock, of any corporation, engage in any activity in competition with
any portion of the Company's Telecommunications Business as it exists at the
time of the termination of Employee's employment.

(c) During employment and for a period of eighteen (18) months after the
termination of employment, absent the expressed, prior written authorization of
the Company's Board of Directors, Employee shall not, directly or indirectly,
whether alone, as a partner of any partnership or joint venture or as an
officer, director, employee, or holder of 5% or more of any class of stock, of
any corporation, solicit any customer of the Telecommunications Business for
purpose of providing goods or services or software that compete with goods or
services or software offered by the Telecommunications Business.

(d) During employment and for a period of eighteen (18) months after the 
termination of employment, absent the expressed, prior written authorization of 
the Company's Board of Directors, Employee shall not, directly or indirectly, 
whether alone, as a partner of any partnership or joint venture or as an 
officer, director, employee, or holder of 5% or more of any class stock, of any 
corporation, solicit, induce or otherwise cause any employee or consultant of 
the Company to terminate or modify their relationship with the Company for the 
purpose of working for, or to become an employee or consultant to or for, any 
entity that provides goods or services or software that compete with goods or 
services or software offered by the Telecommunications Business.

(e) Employee acknowledges and agrees that the services to be rendered by 
Employee to the Company, the information disclosed to Employee during and by 
virtue of his employment, and the Employee's commitments and obligations to the
Company are of a special, unique and extraordinary character, and that the 
breach of any provision of this Section 4 will cause irreparable injury and 
damage to the Company, and consequently the Company shall be entitled to, in 
addition to all other remedies available to it, injunctive and equitable relief 
to prevent a breach all or any part of this Section 4, and to secure the 
enforcement of all or any part of this Section 4.

5. Business Disclosures. During the term of employment with the Company and 
   --------------------
thereafter, Employee will not, without the express, prior written consent of the
Company's Board of Directors, disclose, other than to an authorized employee,
officer or director of the Company, any confidential information of, regarding
or relating to the Company. For purposes of the preceding sentence, the phrase
"confidential information" shall include, but not be limited to, any information
relating to the Company's businesses, customers, trade practices, or trade
secrets and know-how. Upon the termination of Employee's employment for whatever
reason, Employee, without the prior, express written consent of the Board of
Directors, shall not remove

                                       3


<PAGE>
 
from the premises or possession of the Company or retain, publish or 
disseminate, any figures, calculations, letters, customer lists, documents, 
written instruments or any other material of a confidential nature, whether 
originals, photocopies or other facsimile or reproductions thereof, or other 
confidential information of any type or description in connection with or in any
way pertaining to the Company of its affairs.

6.    Development of Inventions and Improvements.
      ------------------------------------------

(a)   Employee will keep the Company informed of any inventions, discoveries, 
improvements, trade secrets, and secret processes made by Employee, in whole or 
in part, or conceived by Employee, alone or with others (herein collectively 
referred to as "Intellectual Property"), if such Intellectual Property results 
from any work Employee may do for or on behalf of the Company or at the request 
or upon the premises of the Company or which work relates to the activities, 
investigations or obligations of the Company or its affiliates (such 
Intellectual Property hereinafter referred to as "Company Work Product"). For 
purposes of the preceding sentence, the term "affiliates" shall include, without
limitation, any entity with which the Company is carrying on a joint enterprise 
or in which the Company has a substantial interest.

(b)   At the expense of the Company, Employee shall assist the Company, its 
agents, employees or nominees, in making application for and obtaining patents 
with respect to any and all Company Work Product in such countries throughout 
the world as the Company shall designate. Employee agrees to and shall execute 
any and all papers necessary to secure on behalf of the Company such United 
States or foreign patents covering Company Work Product which the Company deems 
necessary or appropriate. In addition, Employee shall give the Company any and 
all information in Employee's possession or known to Employee respecting any 
Company Work Product or any patents or applications relating thereto.

(c)   Such Company Work Product shall be the property of the Company, or its 
nominees, whether patented or not, and Employee shall, without charge to the 
Company, assign to the Company all of Employee's right, title, and interest, if 
any, in such Company Work Product and Employee shall execute, acknowledge and 
deliver any instrument confirming the complete ownership by the Company of such 
Company Work Product.

(d)   Employee shall deliver to the Company upon its request therefor, any and 
all sketches, drawings, models, figures, and other materials and information 
created or acquired by Employee during the term of employment with respect to 
any Intellectual Property covered by this Section 6 and to execute and deliver 
to the Company any applications, assignments or other written instruments 
reasonably necessary or appropriate to the Company's securing such patents, or 
the renewal or continuation thereof, or in any litigation or other proceedings 
connected therewith.

(e)   Descriptions of all Intellectual Property, whether patented or not, which 
Employee has made or conceived prior to his employment by the Company, are 
described in Exhibit B hereto, and such Intellectual Property shall be excluded 
from this Agreement. Employee represents, warrants, and covenants that the 
absence of a description of any Intellectual Property on Exhibit B shall 
indicate conclusively that Employee neither owned prior to his employment by the
Company nor has any claim to any such Intellectual Property.


                                       4
<PAGE>
 

(f) Employee shall not, at any time, except as required in the proper conduct of
the business of the Company or as authorized in writing by the Company, publish,
disclose or authorize, assist or permit anyone else to publish or disclose any 
secret or confidential matter relating to any aspect of any of the businesses of
the Company.

(g) This Agreement will further incorporate any and all provisions with respect
to patents, inventions, discoveries, improvements, trade secrets, secret
processes, and data to which the Company may be required to cause its employees
to agree under the terms and provisions of any contract entered into by the
Company with the United States Government or any agency thereof or any foreign
government or agency thereof or any supranational agency, or under the terms of
any subcontract to which the Company under a prime contract issued by any of the
above-mentioned governments or agencies, whether the same be in any contracts to
which the Company is presently or may in the future become a party.

(h) Upon termination of employment, Employee will execute and comply with the 
Termination Statement attached hereto as Exhibit C.

7. Termination of Contract.
   -----------------------

(a) Except as provided in Section 7(c) below, and subject to Section 3(e) 
hereof, this Agreement may be terminated by the Company upon six (6) months 
written notice to Employee.

(b) Subject to Section 3(e) hereof, this Agreement may be terminated by Employee
upon six (6) months written notice to the Company.

(c) Subject to Section 3(e) hereof, the Company may terminate this Agreement for
cause immediately upon written notice to Employee. For purposes of this Section 
7(c), the Company shall have cause for termination under any of the following 
circumstances:

         (i)   Failure on the part of the Employee to exert best efforts in 
performing the functions assigned to Employee by the Company, which failure can 
reasonably be expected to have a material adverse effect on the Company, 
provided that the functions assigned to Employee shall at all times be in 
keeping with the position for which Employee was hired, as described in 
Section 1 of this Agreement; or

         (ii)  Employee is in breach of the terms of Sections 4, 5 or 6 hereof, 
is guilty of dishonesty or chronic absenteeism, or is convicted of a felony, or 
is convicted of a misdemeanor involving moral turpitude.

(d) Termination of this Agreement will not relieve Employee from any liability 
pursuant to Sections 4, 5 or 6 which, by their respective terms, continue beyond
the termination of this Agreement.

8. Disability. If Employee is unable to fulfill the duties of his or her 
   ----------
position by reason of any illness, incapacity or disability, Employee's salary
shall be payable for only 90 days following the onset of such illness,
incapacity or disability, provided, however, that if Employee (i) has applied
for insurance benefits under the Company's long-term disability policy during
said 90 day period, and (ii) has not yet begun to receive payments under said
policy during said 90 day

                                       5


 
<PAGE>
 
period, then Employee's salary shall continued to be payable for up to 180 days
following the onset of such illness, incapacity or disability until the Employee
begins to receive such payments. During the foregoing 90 day period (or 180 day
period, if applicable), Employee's salary, to the extent not covered by the
Company's short-term disability benefits, shall be paid through the use of
Employee's sick leave, if any, accumulated prior to January 1, 1994, but if such
sick leave is or becomes exhausted, Employee's salary shall nevertheless be paid
for the 90 day period (or 180 day period, if applicable). If Employee shall
return to full employment and full discharge of his or her duties during the
term of this Agreement, full compensation shall be prospectively reinstated for
any remaining term of this Agreement.

9. Notice.
   ------

(a) Any notice to be given to Employee under this Agreement shall be in writing 
and delivered by (i) registered or certified mail, return receipt requested; 
(ii) express courier; or (iii) hand-delivery, at an address specified for 
Employee in this Agreement or in any Exhibit hereto or at such other address of 
which written notice has been given to the Company by Employee by any of the 
foregoing means.

(b) Any notice to be given to the Company under this Agreement shall be in 
writing and delivered by any of the means specified in Section 9(a) above, to 
the President, with a copy to the Senior Vice President, General Counsel & 
Secretary, GRC International, Inc., 1900 Gallows Road, Vienna, Virginia 22182.

10. Disputes.
    --------

(a) This Agreement has been executed in and shall be governed by the laws of the
Commonwealth of Virginia.

(b) Any controversy or claim arising out of or relating to Employee's employment
or this Agreement shall be resolved in the courts of Fairfax County, Virginia, 
and Employee hereby submits to the jurisdiction of such courts, and agrees to 
accept service of process from such courts.

(c) It is agreed that in the event of any breach, violation or evasion of the 
terms of this Employment Agreement, such breach, violation or evasion will 
result in immediate and irreparable injury to the Company and will authorize the
Company to seek injunctive relief, including, but not limited to, any order of 
specific performance, as well as all other legal or equitable remedies to which 
the Company may be entitled.

11. Waiver of Breach.  The waiver by the Company of a breach of any provision of
    ----------------
this Agreement by Employee shall not operate or be construed as a waiver of any 
subsequent breach by Employee. No such waiver shall be valid unless set forth in
writing signed by an authorized officer of the Company.

12. Assignment. Employee's services are unique and personal. Accordingly, 
    ----------
Employee may not assign any rights or delegate any duties or obligations under 
this Agreement. The rights and obligations of the Company under this Agreement 
shall inure to the benefit of and shall be binding upon the successors and 
assigns of the Company.

                                       6
<PAGE>
 

13. Severability. Any provision of this Agreement which may be determined to be 
    ------------
unenforceable, invalid or illegal shall be deemed stricken from this Agreement 
and all remaining provisions shall continue in full force and effect.

14. Entire Agreement. This Agreement supersedes all previous Employment 
    ----------------
Agreements between Employee and the Company and contains the entire
understanding of the parties and may not be modified, amended or terminated
unless the provisions of such modification, amendment, or termination are set
forth in writing signed by all of the parties to this Agreement. This Agreement,
and any modification, amendment or termination thereof, shall be approved by
and executed on behalf or at the direction of the Company's Board of Directors.

IN WITNESS WHEREOF, the parties hereto have executed this Employment Agreement 
as of November 2, 1995.

ATTEST:                                          GRC INTERNATIONAL, INC.

/s/ T.E. McCabe                                  By: /s/ Jim Roth
------------------------------------                 ---------------------------
Thomas E. McCabe                                     Jim Roth
Sr. Vice President, General Counsel &                President & Chief Executive
Secretary                                            Officer

WITNESS                                          EMPLOYEE

/s/ Michele L. Zeck                                  /s/ Charles C. Bream
------------------------------------                 ---------------------------
                                                     Charles C. (Cliff) Bream


APPROVED AND RATIFIED BY THE COMPENSATION COMMITTEE OF THE BOARD OF DIRECTORS OF
GRC INTERNATIONAL, INC.

By: /s/ Leslie B. Disharoon
    ---------------------------------------
    Leslie B. Disharoon, Committee Chairman


                                       7
<PAGE>
 
                                                                       EXHIBIT A
                                                                       ---------


                             DETAILS OF EMPLOYMENT
                             ---------------------

EMPLOYEE:           Charles C. (Cliff) Bream
                    ------------------------

ITEM 1(a) Position: Senior Vice President, General Manager - Telecom Division
                    ---------------------------------------------------------

ITEM 1(b) Place of Employment: 1900 Gallows Road, Vienna, Virginia 22182
                               -----------------------------------------

ITEM 2 Effective Date of Employment Agreement:  November 2, 1995
                                                ----------------

       Effective Date of this Exhibit:          November 2, 1995
                                                ----------------
ITEM 3(a) Gross Annual Salary: $140,000
                               --------

ITEM 3(b) Additional Compensation (if any):

      (i)  Stock options to purchase 50,000 shares of GRC International, Inc.
           common stock, subject to the approval of the Compensation Committee
                         -----------------------------------------------------
           of the Board of Directors
           -------------------------

      (ii) Bonus for Fiscal Year Ending June 30, 1996 as Shown in Attachment 1 
           -------------------------------------------------------------------  
           hereto
           ------

ITEM 4 Notice to Employee:

             Charles C. (Cliff) Bream            Charles C. (Cliff) Bream
       --------------------------------      ---------------------------------
                                        and/
             1900 Gallows Road           or      19027 Loudoun Orchard Rd. 
       --------------------------------      ---------------------------------

             Vienna, Virginia 22182              Leesburg, Virginia 22075
       --------------------------------      ---------------------------------



EMPLOYEE:                                    GRC INTERNATIONAL, INC.

/s Charles C. Bream                          By: /s/ Jim Roth
------------------------------                  ------------------------------
Charles C. (Cliff) Bream                        Jim Roth
                                                President & Chief Executive 
                                                Officer



APPROVED AND RATIFIED BY THE COMPENSATION COMMITTEE OF THE BOARD OF DIRECTORS OF
GRC INTERNATIONAL, INC.


By: /s/ Leslie B. Disharoon
   ----------------------------------
                                      Leslie B. Disharoon, Committee Chairman


                                       8
                                               
<PAGE>
 
                                      ATTACHMENT 1 TO BREAM EMPLOYMENT AGREEMENT
                                      ------------------------------------------

                  BONUS FOR FISCAL YEAR ENDING JUNE 30, 1996
                  ------------------------------------------

Employee shall receive the following bonus compensation based on successful 
completion of the milestones indicated in the fiscal year ending June 30, 1996 
("FY96"):

<TABLE> 
<CAPTION> 
   Milestone                                                                           Bonus 
   ---------                                                                           -----
<S>                                                                              <C>   
1. Complete beta testing of OC-3 OSU(TM) Network Interface                         $1,866.67

2. Complete the OC-3 OSU(TM) Network Interface                                     $1,866.67

3. Complete the cost reduction program                                             $5,600.00

4. Produce a working prototype of the OC-12 OSU(TM) Network Interface              $5,600.00

5. Complete an economic justification study for customer use of the 
   OSU(TM) Network Interface                                                       $1,866.67

6. Revise the marketing and sales plans
   to include emphasis on an OEM strategy                                          $3,733.33

7. Complete ISO-9000 certification                                                 $5,600.00

8. Produce OSU(TM) Network Interface revenues of a least $6.5 million
   which are recognized in the Company's financial statements in FY96,
   and, in addition, a backlog of firm purchase orders signed by both the
   Company and the customer totaling at least $3.0 million at the end of FY96     $11,200.00

9. Produce OSU(TM) Network Interface revenues of at least $7.8 million
   which are recognized in the Company's financial statements in FY96,
   and, in addition, a backlog of firm purchase orders signed by both the 
   Company and the customer totaling at least $3.6 million at the end of FY96     $18,666.67
                                                                                  ----------

                                             MAXIMUM POTENTIAL BONUS FOR FY96:    $56,000.00
                                             --------------------------------     ----------
</TABLE> 


                                       9
<PAGE>
 
                                                                       EXHIBIT B
                                                                       ---------

                       SCHEDULE OF INTELLECTUAL PROPERTY
                       ---------------------------------

Employee developed or conceived prior to employment with the Company the 
following Intellectual Property, as that term is defined in Section 6 of the 
Employment Agreement to which this Exhibit is attached, whether or not such 
Intellectual Property is the subject of a patent or patent application:






                                                EMPLOYEE

                                                /s/ Charles C. Bream
                                                ---------------------------
                                                Charles C. (Cliff) Bream


                                                       11/3/95
                                                ---------------------------
                                                (Date)


                                      10
<PAGE>
 
                                                                    EXHIBIT C
                                                                    ---------

                             TERMINATION STATEMENT
                             ---------------------

In connection with the termination of my employment with the Company pursuant to
the above-referenced Employment Agreement, I hereby represent, warrant and 
covenant that:

1.  Upon termination of my employment relationship with the Company I did not 
have in my possession and do not now have in my possession any confidential or 
business property of the Company including, but not limited to, any confidential
information described in Section 5 of the aforementioned Employment Agreement, 
the Company Work Product described in Section 6 of the Employment Agreement or 
any testing equipment, materials, components, sub-assemblies, drawings or 
blueprints.

2.  I have returned or left in the possession of the Company all notebooks which
I used during my employment relationship with the Company.

3.  I have returned to the Company any and all identification cards and credit 
cards issued to me as an employee of the Company and any and all keys to 
property of the Company, including, without limitation, offices of the Company, 
Company cars, and the like.

4.  I am not aware of any action or situation involving any violation of the
Company's Corporate Standards of Conduct by any employee, director, consultant
or representative of the Company, except as follows:


4.  My forwarding addresses are as follows:

HOME ADDRESS                                 BUSINESS ADDRESS

----------------------------------          -----------------------------------

----------------------------------          -----------------------------------

----------------------------------          -----------------------------------

----------------------------------          -----------------------------------

                                            EMPLOYEE:

                                            -----------------------------------
                                            Charles C. (Cliff) Bream

                                            -----------------------------------
                                            (Date)

                                      11