PM Files

The Chairman of the United States Atomic Energy Commission (Lilienthal) to President Truman

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Dear Mr. President: We hand you herewith a memorandum from the members of this Commission on the development of a “Super” bomb. We shall, of course, be glad to discuss the subject with you at any time you desire this.

We have not, of course, transmitted copies of our memorandum to you to the Secretary of State or the Secretary of Defense. In the event you wish to transmit it to them we have enclosed two extra copies.1

Respectfully yours,

David E. Lilienthal

Memorandum for the President by the United States Atomic Energy Commission

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Subject: Development of a “Super” Bomb

The Problem

Since the discovery that an atomic explosion had occurred in Russia, the Atomic Energy Commission has been reviewing its entire program. It has recently been giving particular attention to the possible development of a so-called “Super” bomb. This memorandum contains proposals concerning that development.

In this report we, as members of the Atomic Energy Commission, have set forth a problem which cannot, of course, be finally resolved within the Commission. The question is whether we should now engage [Page 577] in the development of a thermo-nuclear “Super” bomb, the destructive power of which would obliterate an area of 100 or more square miles.

This question has a long history. (See Appendix “B”.2) In reviewing it again at this time, we have had formal advice from the General Advisory Committee (See Appendix “C”3) and informal discussions with the members of that Committee, with members of the Department of State, Department of Defense, the Joint Committee on Atomic Energy, and others.

Ordinarily the Commission, following consultation with the Department of Defense, has taken full responsibility in deciding such matters as the improvement of existing weapons or the development of new types of weapons. The destructive possibilities of a single “Super” are, however, so great and the implications involved in any decision to embark or not to embark upon the development of it so far reaching, that we have considered it our duty to lay the problem before you. We have also considered it our duty to furnish you with our recommendations.

In making these recommendations, we have felt that our role should be more than that of experts concerned with such factors as cost, feasibility, and the most efficient use of fissionable materials. We have felt in this instance that we would be remiss if we did not suggest some of the other factors involved. These include military, diplomatic, and psychological imponderables which, though difficult to assess, are relevant to the ultimate issue of public policy. On that issue we are submitting below our suggestions as to how your decision concerning the “Super” bomb may, in our opinion, be utilized to promote peace or to win a war.

Why is there a necessity for an early decision of policy by the President?

The Joint Committee on Atomic Energy is preparing to take early action on the question of proceeding with this development. A subcommittee on this subject has just visited Commission installations at Berkeley and Los Alamos. They came away with enthusiasm for an immediate program, at highest priority. Several scientists have become missionaries for the project; other equally distinguished people have opposing views. Senator McMahon has stated that he has plans to call a special executive meeting of his full Committee in a matter of weeks. Action by the Committee at that time has been forecast and appears likely.

The Commissioners are all convinced therefore that public discussion of the matter at some stage, probably very soon, is inescapable, [Page 578] is necessary, and is desirable. The public reception of your announcement of the Russian achievement of a bomb is a good precedent. It suggests that public discussion will be most useful and constructive (at whatever stage) if based upon essential facts stated to the country by its President. We are concerned that without such a statement from you, at an early date, there will be public discussion, but it may be based largely on irresponsible conjecture, “leaks”, politically motivated or inflammatory utterances, and the like. Only confusion, and worse, will be the result.

Nature of “Super” Bomb

The explosive element in such a bomb would be deuterium. This is an isotope of hydrogen (the form of hydrogen which combines with oxygen to form “heavy water”) which makes up one part in five thousand of ordinary hydrogen and is readily separated therefrom. It is believed probable that if the temperature of part of a mass of deuterium could be raised to … degrees Centigrade, a thermonuclear reaction would start.… Such a thermo-nuclear reaction would liberate enormous amounts of energy, comparable pound for pound with the fission process. It is believed possible that a fission bomb could be used as a “match” to ignite the deuterium just as a fuse is used to ignite a charge of powder. As in the latter case, the size of the explosion would be limited only by the amount of deuterium present.

We find ourselves in unanimous agreement on many points. These are of two kinds. The first kind are technical and demonstrable. We accept them as premises. The second are of more general character but certainly germane to the problem and have entered into our consideration.

Technical Premises

A “Super” as now contemplated is from 100 to 1,000 times as powerful in terms of energy release as the Hiroshima bomb. Also, in contrast to fission bombs, the power of a single “Super” can be increased indefinitely by adding the relatively cheap explosive needed.
There is a better than even chance it can be made to work, though there is no certainty of success. The probable minimum development period is three years.
Probably no definitive test short of making a bomb can be anticipated.
The general principles of the reaction used and the amount of the consequent energy release are so well known that no secrets will be released by general discussion at either the diplomatic or public level.
There is a possibility that the radioactivity released by a small number (perhaps ten) of these bombs would pollute the earth’s atmosphere [Page 579] to a dangerous extent. We hope for a tentative answer to this question shortly.
The primary explosive, deuterium, is plentiful and relatively inexpensive.
There is no apparent peacetime application of this type of nuclear reaction, nor of the materials required for it.
The Russians are familiar with the ideas and probably can develop a bomb in a period comparable to that which we would need.
The possibility of delivery by ship or boat may make this country more vulnerable than Russia to this type of bomb since air delivery could not take full advantage of the unlimited energy release possible with very large charges.
Detailed study of possible programs and expenditures indicates that the development and production of “Super” bombs may not greatly increase our retaliatory capacity in terms of square miles of destruction by 1956, as compared with continued development and use of fissionable material for the production of fission bombs.
It is believed that we would be able to detect the first test explosion of this type if made by the Russians.

General Considerations

Most of those who have studied the “Super” bomb feel that it would be a tool for mass destruction beside which the fission atomic bomb would seem puny even if the latter’s efficiency were increased to the foreseeable limit.
To have reasonable assurance that we would develop this bomb as soon as the Russians might if they applied great effort to it, would require vigorous action now.
Such action would change substantially our present National program of research and development and could not be kept secret.
To be successful, an all-out “Super” program would require support from the scientific community. It is doubtful whether such support could be obtained unless scientific leaders understood and supported the National policy to be implemented by such a program.
The comments in (4) apply with almost equal strength to the Nation as a whole.
Knowledge of the “Super” is so widespread that a decision not to go ahead could hardly be kept secret.
For the United States and Russia to proceed with “Super” programs would intensify in a new way the arms race between the two countries.

Bearing in mind the above premises and considerations, we have explored courses of action that might help toward answering the questions of the following kind:

If this country wishes to eliminate all weapons of mass destruction from the world’s armaments can the way in which we handle this [Page 580] question (to proceed or not proceed with development of a “Super”) be used to break the present stalemate in the United Nations on the question of international control?
If this country wishes to keep fission atomic bombs in our armament, or is really convinced that negotiations for control are hopeless, can we use the “Super” development or the decision not to develop it, as a diplomatic or psychological factor in the cold war?
If war is inevitable or likely, is our position improved by the development and possession of the “Super”?

The views of the Commissioners on the question of proceeding or not proceeding with a “Super” Bomb.

We recognize fully that this decision is one for the President. We hope it may be helpful to you to present our own conclusions:

First: Should the Commission be directed to proceed now with the development of a “Super” bomb?

Commissioners Lilienthal, Pike, and Smyth recommend that your decision be against the development of a “Super” bomb at this time.

Commissioners Dean and Strauss state their views in paragraph d below.

Further, Commissioner Strauss is of the opinion that our memorandum to you should await our receipt of the views of Defense and State on the military and diplomatic considerations. The other Commissioners, while recognizing, of course, that you may wish to call for the views of Defense and State (and perhaps other agencies) believe it better that this function be done by you, or at your direction, rather than attending to it ourselves prior to your consideration of the problem.

Second: What course of action should follow such a decision?

Here there are several views among us, which we shall list briefly. A further statement of these views will be found in Appendix “A”.

Commissioners Lilienthal, Pike, and Smyth recommend that the President make public his conclusion as soon as feasible.
Commissioners Lilienthal, Pike and Smyth, believe the statement should contain an assertion that it does not appear to the President that at this time the development of this weapon is consistent with this country’s program for world peace or our own long term security.
Such a statement, we suggest, might well, in addition to the reasons for your conclusions, contain some information about the characteristics and effects of this weapon (such as are indicated in this memorandum) and that the prospects of producing such a weapon are as stated herein. We are prepared to suggest other points you might find worthy of inclusion in such a statement, of which the one made by Dr. Smyth in paragraph c below is an example. For present purposes we merely state that this is a course that we favor.
Commissioner Smyth suggests that the President’s statement be the occasion for a proffer of renewed negotiations for international control of atomic energy, or even a broader proposal, going beyond the [Page 581] atom; though he considers that the present recommended decision should not be related to any specific international pledge or treaty, he does feel that failure of renewed attempts at international agreement might require an early review of our decision not to make a “Super”.
Commissioners Dean and Strauss have a different recommendation which they state as follows:

Utilize this possibility to reopen with the Soviet via secret diplomatic channels the consideration of satisfactory international controls of weapons of mass destruction. If this fails, or if it is felt that the possibility cannot thus be soon exploited, then proceed, if the Defense Establishment concurs, with the development, and announce this fact publicly.

Six members* of the Commission’s General Advisory Committee recommended course b above. (See Appendix “C”.) Two members of that Committee, however, recommend that the President state that we will not proceed, but only upon condition that Soviet Russia gives its pledge that it too will not proceed in this kind of development.

Appendix “A”

(Note: Commissioners Lilienthal, Dean, and Smyth have prepared the following statements of their individual views. Commissioners Pike and Strauss are not at present in Washington, though they participated in the preparation of the Commission’s memorandum. They may have supplementary individual views to submit at a later date.)

Views of David E. Lilienthal

The question you have before you is whether this Government should now embark upon an intensive undertaking for the development and production of Superbombs.

In the Commission’s Memorandum to you we have tried to set forth what we believe to be the essential facts you will need for determination of this question. You also have before you the views on this matter of the General Advisory Committee, appointed by you pursuant to statute. Six members of that Committee have recommended against such an undertaking, for reasons with which I am in substantial agreement.

There is an underlying consideration which to me seems decisive against launching this undertaking now.

The country’s policy, as I understand it, is that we remain strong, and at the same time work for the promotion of peace in the world. It is my view that to embark upon this program at this time would not [Page 582] increase our over-all strength, and at the same time such a program would set the country upon a course that works against and would constitute a set-back for the strategy for peace of your Administration.

Staying strong—in all of its ramifications, military and in other ways related to our security—is a firm part of our policy. The methods by which we seek to remain strong range from military aid to Europe to economic reconstruction in Europe and other parts of the world; it includes the Point Four program and the long-range efforts in the UN and its many affiliated agencies, such as F.A.O. and so on. This purpose is also served by the continued increase in our atomic stockpile, under present approved programs, and the improvement of these weapons for tactical purposes. But I find no basis for a belief that the Superbomb would add to our strength. Moreover, there is reason to believe that it will actually diminish that over-all strength; on this point the comments of the distinguished members of the General Advisory Committee seem to me most persuasive.

The American policy and program for peace has made encouraging progress. As of today it has a fair prospect of growing steadily stronger, as the months go by. To endanger that course and to contradict its premise by launching now on the development and production of Superbombs seems to me a reversal of our course, at the very time when the prospects are slowly improving. It may well close the door on a continuation of our present policies for promoting peace.

This country is the possessor of a substantial and growing stockpile of atomic weapons, and a large military arm with which to deliver those weapons if need be. If in addition it now sets out to produce something capable of almost unlimited destruction, which has no peaceful applications whatever, we must be prepared to have a large part of the world believe that we are going far beyond any possible military needs, that we have abandoned our program for peace and are resigned to war.

Here at home the initiation of this course would serve to confirm and to intensify the already serious over-valuation placed upon atomic weapons by the American people. This would be injurious to our security.

I have been disturbed by the fact that there exists a widely held notion that an atomic weapon stockpile affords this country a relatively cheap and easy solution of our problems of military security, of the problems of maintaining peace by deterrent and of preventing the spread of Communism. I associate myself with those who believe we have suffered, in many ways, from this over-valuation and wish to add this point: to launch upon a program of Superbombs would set us upon still another costly cycle of misconception and illusion about the value to us of weapons of mass destruction as the chief means of protecting ourselves and of furthering our national policy.

[Page 583]

As is pointed out in the General Advisory Committee letters, without Superbombs we do continue to maintain a deterrent against the Russians in our power to retaliate with our stockpile of atomic weapons. The difference in the amount of damage that could be inflicted on Russia by Superbombs as compared with A-bombs is not significant; it does not, in my opinion, by any means constitute enough difference to outweigh the serious damage to your policy (which is the policy of this country) that is involved in starting down the road of the Superbomb program.

Views of Commissioner Gordon Dean

I cannot subscribe to the view that we should forego the development and announce in a public statement our decision not to perfect the weapon.

To announce that we will not undertake such a development is to grant to the USSR a potential monopoly in this field. This would in my opinion have a bad effect upon the American people. It might well shake the confidence of our friends in Western Europe. It would have no good effect on the Kremlin.

In my opinion it would be a mistake to renounce the development at a time when considerable precise knowledge of the weapon is lacking and to make this renunciation without first having a considered judgment as to its military and psychological value in deterring an aggressor or waging a war.

If it has such value, and I think it may have, the development should not be abandoned. I think that the possibility of such a weapon might be the occasion for supplying a hypodermic in the realm of international cooperation. I visualize the following as a possible useful course of action:

The Executive would advise the Kremlin through secret diplomatic channels of the thermo-nuclear possibility and its destructive effects (this is now generally known to them); state that we do not wish to engage in such a development; that it illustrates the importance of the two countries working out immediately systems for international control of weapons of mass destruction on a basis to be outlined by the Executive. A refusal by the USSR to enter in good faith immediately upon such discussions as the Executive would outline would be the occasion for an American “white paper” describing our efforts.

If Russia persists in her present course and her stockpile continues to grow, we must face the possibility that she might be deterred if she knew that a single weapon in our stockpile could obliterate Moscow. The weapon might cause her to postpone an aggressive war. It is axiomatic in warfare that attack brings retaliation.

If efforts along the lines indicated above should fail and we should find ourselves some day in war with Russia, the weapon must be regarded as a reprisal weapon which might be a decisive weapon. As a [Page 584] strategic weapon its possibilities are clear, assuming that deliverability can be assured. It may have uses not at first supposed in the tactical field such as against large concentrations of troops, a fleet, an island or a large air base area. There are no serious problems in deliverability except the inherent ones of the planes’ range and the likelihood of interception.

This suggested course of action recognizes that possibilities for international control should be pursued, but pursued in such a manner as to make possible a successful result. It also recognizes that the prospect of agreement is not good and that an aggressive war by the USSR is, unfortunately, a strong possibility.

Views of H. D. Smyth

In approaching this question, I considered first the strictly military position of this country over the next five or ten years in terms of the development of “Super” bombs both here and in Russia. I next tried to evaluate the effect on the thinking of the people in this country and elsewhere which might result from our development of a still larger weapon of mass destruction. This seems to me an important factor in the success of our attempt to achieve a stable world either by war or by diplomacy. Finally, I considered the present state of atomic, energy negotiations in the United Nations and the possible effect which might result from a Presidential announcement and subsequent public discussion.

I have concluded that the military advantage of “Supers” to us is doubtful even if the Russians do develop them. I have concluded that our general standing in the world would be worsened by our development of “Supers”.

Finally, I feel that the decision either way cannot and should not be secret. The tonic effect of refreshed discussion might be very great at this time, particularly if it were based on the idea of the “Super” as well as on the Russian success with the fission bomb. I believe this success has made the Baruch plan outmoded and that a new approach is needed. New negotiations might be no more successful than the old but they should be tried.

I feel that discussion will be more vigorous and more fruitful if it starts from a negative decision than from one to go ahead. A negative decision is a gesture of good faith and optimism. Also, incidentally, such a decision is more easily reversed than a one to go ahead full speed at the present time.

Though a bare announcement of a decision without a correlated statement of policy does not appear likely to be fruitful, it does not seem wise to me to state at this time what circumstances might cause us to reverse our course of action and to go ahead with development of the “Super”. I would not want to make our position dependent on some [Page 585] specific act or statement by the Russians, nor to have the threat of a “Super” bomb development handing [hanging?] over negotiations.

Since I have given much thought and study to questions of this kind during the past eight years, I am keenly aware of my lack of special competence in this field. Furthermore, I doubt the ability of even the wisest to predict future events. It is such doubts as these that have lead me to include “an early review of our decision” in my recommendation. I sincerely hope no change in this decision will ever become necessary.

  1. Transmitted to Secretary Acheson by President Truman on November 14
  2. Not printed.
  3. See letter from Oppenheimer to Lilienthal, October 30, and footnote 5 thereto, p. 569.
  4. J. R. Oppenheimer, James B. Conant, Hartley Howe, Cyril Stanley Smith, L. A. Dubridge, Oliver E. Buckley. [Footnote in the source text. A typewritten addition on the source text indicates that Glenn Seaborg of the Committee was absent.]
  5. Enrico Fermi, I. Rabi. [Footnote in the source text.]