Nuclear Museum Logo
Nuclear Museum Logo

National Museum of Nuclear Science & History

Acheson-Lilienthal Report

The Acheson-Lilienthal Report was a turning point of the Cold War, providing an opportunity to avoid a nuclear arms race and advocating the sharing of knowledge of nuclear energy and inspections to ensure its development for only peaceful use. However, these terms were amended by Bernard Baruch, who was appointed by President Truman to present the report to the United Nations. The modified plan, known as the Baruch Plan, was rejected by the Soviet Union. This letter of transmittal accompanied the Acheson-Lilienthal Report.

Document Type:
Dean Acheson

March 17, 1946

Dear Mr. Secretary [James F. Byrnes]:

Your committee was appointed on January 7, 1946, with the following terms of reference:

Anticipating favorable action by the United Nations Organization on the proposal for the establishment of a commission to consider the problems arising as to the control of atomic energy and other weapons of possible mass destruction, the Secretary of State has appointed a Committee of five members to study the subject of controls and safeguards necessary to protect this Government so that the persons hereafter selected to represent the United States on the Commission can have the benefit of the study.

At our first meeting on January 14, the Committee concluded that the consideration of controls and safeguards would be inseparable from a plan of which they were a part and that the Commission would look to the American representative to put forward a plan. At that meeting we also agreed that it was first essential to have a report prepared analyzing and appraising all the relevant facts and formulating proposals. In order that the work should be useful, it was necessary to designate men of recognized attainments and varied background, who would be prepared to devote the major part of their time to the matter.

On January 23, 1946, we appointed as a Board of Consultants for this purpose: Mr. David E. Lilienthal, Chairman of the Tennessee Valley Authority, who acted as Chairman of the consulting Board; Mr. Chester I. Barnard, President of the New Jersey Bell Telephone Company; Dr. J. Robert Oppenheimer, of the California Institute of Technology and the University of California; Dr. Charles Allen Thomas, Vice President and Technical Director, Monsanto Chemical Company; and Mr. Harry A. Winne, Vice-President in Charge of Engineering Policy, General Electric Company.

The Board of Consultants has spent virtually its entire time, since the date of appointment, in an intensive study of the problem, and has now completed its report, which is transmitted herewith.

A preliminary draft of this report was first presented to your Committee ten days ago. Extensive discussion between the Committee and the Board led to the development of further considerations embodied in a subsequent draft. Still further discussion resulted in the report now transmitted.

We lay the report before you as the Board has submitted it to us “not as a final plan, but as a place to begin, a foundation on which to build.” In our opinion it furnishes the most constructive analysis of the question of international control we have seen and a definitely hopeful approach to a solution of the entire problem. We recommend it for your consideration as representing the framework within which the best prospects for both security and development of atomic energy for peaceful purposes may be found.        

In particular, we are impressed by the great advantages of an international agency with affirmative powers and functions coupled with powers of inspection and supervision in contrast to any agency with merely police-like powers attempting to cope with national agencies otherwise restrained only by a commitment to “outlaw” the use of atomic energy for war. In our judgment the latter type of organization offers little hope of achieving the security and safeguards we are seeking.

We are impressed also by the aspect of the plan which concentrates in the hands of the international agency only the activities which it is essential to control because they are dangerous to international security, leaving as much freedom as possible to national and private research and other activity.

We wish to stress two matters brought out in the Board’s report—matters of importance in considering the report’s proposals as they affect the security of the United States both during the period of any international discussion of them and during the period required to put the plan into full effect.

The first matter concerns the disclosure of information not now generally known. The report points out that the plan necessitates the disclosure of information but permits of the disclosure of such information by progressive stages. In our opinion various stages may upon further study be suggested. It is enough to point out now that there could be at least four general points in this progression. Certain information, generally described as that required for an understanding of the workability of proposals, would have to be made available at the time of the discussion of the proposals in the United Nations Atomic Energy Commission, of the report of the Commission in the Security Council and General Assembly of the United Nations, and in the national legislatures which would be called upon to act upon any recommendations of the United Nations. We have carefully considered the content of this information, and in our discussions with the Board have defined it within satisfactory limits. We estimate the degree of its importance and the effect of its disclosure to be as follow: If made known to a nation otherwise equipped by industrial development, scientific resource and possessing the necessary raw materials to develop atomic armament within five years, such disclosure might shorten that period by as much as a year. Whether any nation—we are excluding Great Britain and Canada—could achieve such an intensive program is a matter of serious doubt. If the program were spread over a considerably longer period, the disclosure referred to would not shorten the effort appreciably.

The next stage of disclosure might occur when the proposed international organization was actually established by the action of the various governments upon the report of the United Nations. At this time the organization would require most of the remaining scientific knowledge but would not require the so-called technical know-how or the knowledge of the construction of the bomb.

By the time the organization was ready to assume its functions in the field of industrial production it should, of course, require the technological information and know-how necessary to carry out its task. The information regarding the construction of the bomb would not be essential to the plan until the last stage when the organization was prepared to assume responsibility for research in the field of explosives as an adjunct to its regulatory and operational duties.

The second matter relates to the assumption or transfer of authority over physical things. Here also the plan permits of progress by stages beginning in the field of raw material production, progressing to that of industrial production, and going on to the control of explosives.

The development of detailed proposals for such scheduling will require further study and much technical competence and staff. It will be guided, of course, by basic decisions of high policy. One of these decisions will be for what period of time the United States will continue the manufacture of bombs. The plan does not require that the United States shall discontinue such manufacture either upon the proposal of the plan or upon the inauguration of the international agency. At some stage in the development of the plan this is required. But neither the plan nor our transmittal of it should be construed as meaning that this should or should not be done at the outset or at any specific time. That decision, whenever made, will involve considerations of the highest policy affecting our security, and must be made by our government under its constitutional processes and in the light of all the facts of the world situation.

Your Committee, Mr. Secretary, awaits your further instructions as to whether you believe it has performed the task you assigned to it and may now be discharged or whether you wish it to go further in this field under your guidance.

Dean Acheson,


Vannevar Bush

James B. Conant

Leslie R. Groves,

Major General, U.S.A.

John J. McCloy

More Historical Resources: