Foreign Relations of the United States, 1977–1980, Volume XXVI, Arms Control and Nonproliferation

156. Letter From the Acting Director of the Energy Research and Development Administration (Fri) to the President’s Assistant for National Security Affairs (Brzezinski)¹

Washington, May 9, 1977

Dear Dr. Brzezinski:

The Energy Research and Development Administration (ERDA) has reviewed the recommendations of the Director, Arms Control and Disarmament Agency, set forth in a memorandum to you dated April 29, 1977.²

[Omitted here is a brief history of 1974–1976 deliberations on nuclear testing.]

Redefining the yield upon which the threshold is based in the manner recommended by ACDA would unilaterally and significantly lower the yield threshold to which the United States could test and would be asymmetrically unfavorable to the United States. [2 lines not declassified] ERDA and DoD testing prior to the effective date of the Threshold Test Ban Treaty was based on the ability to test up to a design yield of 150 kilotons after this treaty was implemented. When testing at design yields up to 150 kilotons, the potential excursions above 150 kilotons are insignificant in comparison [4 lines not declassified]

[4 lines not declassified] If the ACDA proposal of 150 kilotons maximum credible underground yield were accepted, this development technique could not be performed for certain weapon systems. [11 lines not declassified]

With regard to ACDA’s comments concerning insertable nuclear component (INC) warhead technology, the concept of utilizing insertable components for safety and security purposes is an old one. [2 lines not declassified] The recent renewed United States interest in this concept arises from both the added safety and security that could be obtained from separable components and from the economic and operational advantages offered by convertible weapons. A unilateral decision to arrest the development of such warheads for United States use would in no way impede Soviet use of this concept. [4½ lines not declassified]

[1 paragraph (7 lines) not declassified]

Sincerely,

Robert W. Fri³
Acting Administrator

1. Source: Washington National Records Center, OSD Files: FRC 330–80–0017, Box 63, A–400.112 1977. Secret; Restricted Data. Copies were sent to Warnke, Vance, Harold Brown, Lance, George Brown, and Turner. A stamped notation at the top of the first page reads “SEC DEF HAS SEEN.” Harold Brown initialed the top right-hand corner of the memorandum and wrote “5/10.”
2. See Document 154.
3. Printed from a copy that bears Fri’s stamped signature.