G/PM files, lot 68 D 349, “H-Bomb Report to Pres.”

Memorandum by the Acting Secretary of Defense (Foster) to the Secretary of State and the Chairman of the Atomic Energy Commission (Dean)

top secret
  • Subject:
  • Intensification of the Thermonuclear Weapons Program

Recent developments in thermonuclear weapons are so significant that I feel our effort in this field should be re-evaluated by our Special Committee of the National Security Council.

[Page 879]

As you know, the President in his January 31, 1950 letter to Mr. Lilienthal, directed that the scale and rate of effort in the thermonuclear program be determined jointly by the Atomic Energy Commission and the Department of Defense and that the necessary ordnance developments and carrier program be undertaken concurrently.1 These matters have been a subject of continuing study by the Military Liaison Committee who have kept me and the Joint Chiefs of Staff informed. Recently, I sent Mr. Dean a copy of my reply to Senator McMahon in response to a question from the Joint Committee on Atomic Energy as to Department of Defense views on the present thermonuclear program.2

While I agree that the present thermonuclear program constitutes a satisfactory response to the Presidential Directive in terms of technical feasibility and on the basis of facts then known, there is a growing feeling in the Department of Defense that intensification and broadening of effort should be initiated now in view of the probability that the present approach to thermonuclear weapons may succeed. My purpose in raising the question at this time is the realization that a considerable period will be necessary to organize the personnel and facilities required to sharply expand existing weapon development activity. I am also informed that this subject has been discussed by the Commission and that the matter is still under review.

The urgency with which we must approach this problem is determined in large measure by our estimates of the probability that the Russians may achieve a thermonuclear weapons capability. Information which has been presented to me suggests that we can only assume that the Russians may be as far along as we are. In this connection, I call your attention to the views of the three Secretaries as expressed in the document attached. Further, I refer you to the position of the Joint Chiefs of Staff as expressed in their memorandum of November 23, 1949, copy attached.3 General Bradley tells me that the Joint Chiefs are preparing a more detailed military requirement in the light of recent thermonuclear progress.

Possession of thermonuclear weapons in relatively small quantities—of the order of 100—in such form that they can be readily delivered, would constitute a military potential of the greatest possible significance. It would be disastrous if the Russians should succeed [Page 880] in developing such a potential in advance of the United States.

I suggest that the Committee discuss this matter at the earliest possible moment.

William C. Foster


Memorandum by the Acting Secretary of the Army (Alexander), the Acting Secretary of the Navy (Whitehair), and the Secretary of the Air Force (Finletter) to the Secretary of Defense (Lovett)

top secret
  • Subject:
  • Action Necessary to Achieve a Thermonuclear Weapon Capability

On 23 November 1949 the Joint Chiefs of Staff sent a memorandum to the Secretary of Defense in which they stated, among other things, that the possession of thermonuclear weapons by the USSR without such possession by the U.S. would be intolerable and recommended that the Atomic Energy Commission take steps to determine the feasibility of a thermonuclear weapon. The President on January 31, 1950 wrote a letter to the Chairman of the Atomic Energy Commission directing the Commission to proceed to determine the technical feasibility of the thermonuclear weapon, the scale and the rate of effort to be determined jointly by the Atomic Energy Commission and the Department of Defense, and directing that the necessary ordnance program and carrier program be undertaken concurrently.

Recent developments in experimentation by our own scientists have shown that there is a serious possibility that the Russians will be successful in developing a thermonuclear weapon. We are informed by competent authorities, including those at Los Alamos, that Klaus Fuchs 4 possessed and may be presumed to have transmitted to the Russians a full understanding of the Los Alamos thermonuclear weapon feasibility report of April 1946. As you know, this report contained all the essential ideas which led to the Greenhouse George shot in May 1951.5 The George shot in turn demonstrated the principle … which greatly increased the probability of a practical and economical thermonuclear weapon and thus precipitated our current redirected development program. [Page 881] Therefore we must assume, for planning purposes, that the Russians have at their disposal all the essential ideas which led to our present thermonuclear program.

In this connection, there is persuasive evidence that the Russians are now producing both enriched Uranium and Plutonium. This is a new development, since the first two Russian shots contained Plutonium only, while the third was a composite of Plutonium and Uranium. The fact that the Russians have developed production of enriched Uranium means that they are faced with no major production problems in developing thermonuclear weapons, since we are informed that the production of Lithium–6 and Deuterium is simple and cheap by comparison.

In contrast to this Russian activity, the U.S. thermonuclear effort was small between the years 1946 and 1950. Action was resumed only after the first detection of the Russian fission bomb explosion. We have been informed that accordingly it is wholly possible that the Russians may be abreast of, or even ahead of, us in the development of thermonuclear weapons.

For these reasons we recommend that you take up with the Special Committee of the National Security Council designated by the President to advise him on atomic matters the desirability of a directive to the Atomic Energy Commission to intensify its efforts in the development of thermonuclear weapon specifically, we recommend that you seek the support of the Special Committee for the rapid development of a second thermonuclear weapons laboratory. We do not suggest that this be the limit of the intensification of our thermonuclear program, but rather that it be a first step. Our broader suggestion is that the prestige and authority of the National Security Council and the President be placed back of a vigorous directive for the speeding up of the thermonuclear program.

  • Archibald S. Alexander
  • Francis P. Whiteahir
  • Thomas K. Finletter
  1. See the Report by the Special Committee of the National Security Council to President Truman on Development of Thermonuclear Weapons, Jan. 31, 1950, Foreign Relations, 1950, vol. i, p. 513.
  2. Not found in Department of State files.
  3. For text, see Foreign Relations, 1949, vol. i, p. 595.
  4. British atomic scientist arrested for espionage in February 1950.
  5. For documentation on nuclear weapons testing in 1951, see Foreign Relations, 1951, vol. i, pp. 685 ff.