Foreign Relations of the United States, 1961–1963, Volume VII, Arms Control and Disarmament

307. Draft Memorandum From Director of Central Intelligence McCone to Secretary of Defense McNamara⁰

Washington, July 2, 1963.

SUBJECT

• Comments on Conclusions of the White Papers (Draft) on Nuclear Testing Problems¹

1. A forceful test ban would freeze the present status of nuclear weapons except for modest refinements which can be accomplished in the laboratories without testing, or improvements which can be accomplished by clandestine testing under the threshold which will be discussed later.

2. This will mean that the Soviets will preserve their lead in weapons ranging from 6,000# to 25,000# in weight and in yields from 13 to 100 megatons. Our estimates lead to the conclusions that the Soviets now possess missile delivery warheads of about 25 megatons and are in the process of developing a missile which can deliver a 100-megaton warhead. It is apparent that these large warheads can destroy vast areas from thermo effect if the large megaton warheads are exploded at high altitude. It does not appear that weapons of this type would be useful against our hardened missile sites and it does not appear to me that the Soviets will plan such uses, as they will have several hundred ICBMs capable of delivering warheads of about 10 megatons. These, I believe, would be used against our missile sites.

3. It is true that during the period of which I am speaking we will build many more ICBMs and Polaris missiles and will outnumber the Soviets by 3 or 4. It is also true that during this period the Soviets will be hardening their ICBM sites as they now appear to be doing and these will be less vulnerable to our comparatively low yield warheads.

4. I therefore conclude that in the field of strategic weapons we will be at a disadvantage under a test ban. The technology proven in our last test series can be fully developed and weaponized to produce warheads at yields 3 to 5 times as great as those we now have with no increase in weight. While this will not equal the very large warheads of the Soviets, it will give us a far more effective offensive capability than we would otherwise possess.

0. Source: Central Intelligence Agency, DCI, ER Subject Files, White Papers: Nuclear Test Ban 3/1/63-1/21/64. Top Secret. The source text does not indicate whether a final version of this memorandum was sent.
1. A series of draft white papers on the strengths and weaknesses of a nuclear test ban was prepared in the Office of the Secretary of Defense in June and July of 1963. None appears to have reached final form. (Kennedy Library, National Security Files, Departments and Agencies Series, ACDA, Disarmament, Testimony, and ibid., DOD, Vol. IV, 1/63-6/63)