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

154. Memorandum From the Director of the Arms Control and Disarmament Agency (Warnke) to the President’s Assistant for National Security Affairs (Brzezinski)¹

Washington, April 29, 1977

SUBJECT

• Proposed Underground US Nuclear Weapons Test Program for the Second Half of Fiscal 1977

With regard to the test program proposed by ERDA² for the second half of Fiscal 1977, I recommend:

1. a review of the present US policy for tests near the 150 kiloton limit established by the Treaty on the Limitation of Underground Nuclear Weapon Tests,³ and deferral of a decision regarding REBLOCHON and SCANTLING—the two proposed tests near this limit—pending the completion of such a review. The current policy of allowing tests at design yields of up to 150 kilotons in face of the actual yield limit of 150 kilotons specified by the Treaty is defective because it allows tests with an unacceptably high risk of violating the Treaty. A more prudent approach should be adopted. The best approach appears to be limiting tests to devices having a maximum credible underground yield no greater than 150 kilotons;

2. an interagency study of the military utility and the arms control implications of developing and deploying nuclear weapons with insertable nuclear components, and, pending completion and review of this study, deferral of a decision on the conduct of the KNIGHTHEAD test in support of such development. I am concerned about the adverse aspects of this technology with regard to:

(a) our non-proliferation and other arms control goals, since it would lower and blur the nuclear threshold,

(b) the security against theft of the small and highly portable removable nuclear components, and

(c) degradation of conventional capabilities if the weapon is to function in this mode as well as in the nuclear mode;

3. deferral of a decision regarding BEAFORT and DANBO pending comments and decision on the interagency study regarding the SM–2 called for in NSDM 341.⁴ In light of Secretary Brown’s decision not to request the ERDA to initiate a phase 3 program this month,⁵ such a deferral should not materially affect a future positive decision regarding a nuclear warhead for SM–2. I am not persuaded by the ERDA representatives’ certification that DANBO has significant technology implications over and above those established for the SM–2 as a justification for carrying out this test.

Paul C. Warnke

1. Source: Washington National Records Center, OSD Files: FRC 330–80–0017, Box 63, A–400.112 1977. Secret; Restricted Data.
2. See Document 150.
3. Or the Threshold Test Ban Treaty (TTBT), signed by the U.S. and the Soviet Union on July 3, 1974. For the text of the Treaty see Documents on Disarmament, 1974, pp. 225–229.
4. The Ford administration issued National Security Decision Memorandum 341 on November 24, 1976. (Ford Library, National Security Adviser, National Security Decision and Study Memoranda, Box 1, NSDM 341)
5. Not found.