Memorandum discussed with the President
April 25, 1945
1. Within four months we shall in all probability have completed the most terrible weapon ever known in human history, one bomb of which could destroy a whole city.
2. Although we have shared its development with the UK, physically the US is at present in the position of controlling the resources with which to construct and use it and no other nation could reach this position for some years.
3. Nevertheless it is practically certain that we could not remain in this position indefinitely.
a. Various segments of its discovery and production are widely known among many scientists in many countries, although few scientists are now acquainted with the whole process which we have developed.
b. Although its construction under present methods requires great scientific and industrial effort and raw materials, which are temporarily mainly within the possession and knowledge of US and UK, it is extremely probable that much easier and cheaper methods of production will be discovered by scientists in the future, together with the use of materials of much wider distribution. As a result, it is extremely probable that the future will make it possible to be constructed by smaller nations or even groups, or at least by a large nation in a much shorter time.
4. As a result, it is indicated that the future may see a time when such a weapon may be constructed in secret and used suddenly and effectively with devastating power by a willful nation or group against an unsuspecting nation or group of much greater size and material power. With its aid even a very powerful unsuspecting nation might be conquered within a very few days by a very much smaller one, although probably the only nation which could enter into production within the next few years is Russia.
5. The world in its present state of moral advancement compared with its technical development would be eventually at the mercy of such a weapon. In other words, modern civilization might be completely destroyed.
6. To approach any world peace organization [the United Nations] of any pattern now likely to be considered, without an appreciation by the leaders of our country of the power of this new weapon, would seem to be unrealistic. No system of control heretofore considered would be adequate to control this menace. Both inside any particular country and between the nations of the world, the control of this weapon will undoubtedly be a matter of the greatest difficulty and would involve such thorough-going rights of inspection and internal controls as we have never heretofore contemplated.
7. Furthermore, in the light of our present position with reference to this weapon, the question of sharing it with other nations and, if so shared, upon what terms, becomes a primary question of our foreign relations. Also our leadership in the war and in the development of this weapon has placed a certain moral responsibility upon us which we cannot shirk without very serious responsibility for any disaster to civilization which it would further.
8. On the other hand, if the problem of the proper use of this weapon can be solved, we would have the opportunity to bring the world into a pattern in which the peace of the world and our civilization can be saved.
9. As stated in General Groves' report, steps are under way looking towards the establishment of a select committee of particular qualifications for recommending action to the Executive and legislative branches of our government when secrecy is no longer in full effect. The committee would also recommend the actions to be taken by the War Department prior to that time in anticipation of the postwar problems. All recommendations would of course be first submitted to the President. [Truman agreed to the formation of this committee, which would be called the Interim Committee]
Source: Michael B. Stoff, ed., The Manhattan Project: A Documentary Introduction to the Atomic Age (Philadelphia: Temple University Press, 1991), pp. 95-96.