Dear Mr. Prime Minister:1 I have for a long time given serious and thoughtful consideration to the issue you raise in your communication of September 24 regarding the continuation of nuclear testing, which has been the subject of discussion between us in the past.2
Unfortunately, I have been able to reach no other conclusion than that for the time being and in the present circumstances, the security of the United States, and, I believe, that of the free world, depends to a great degree upon what we learn from the testing of nuclear weapons. We are at a stage when testing is required for the development of important defensive uses of nuclear weapons, particularly against missiles, submarines, and aircraft, as well as to reduce further the fallout yield from nuclear weapons. To stop these tests in the absence of effective limitations on nuclear weapons production and on other elements of armed strength and without the opening up of all principal nations to a measure of inspection as a safeguard against surprise attack in which nuclear weapons could be used is a sacrifice which would be dangerous to accept.3
We are aware of the preoccupations with the question of health hazards connected with nuclear testing.4 We believe that these are ill founded. However, we have pledged to conduct those tests which may be necessary only in such a manner as will keep world radiation from rising to more than a small fraction of the levels which might be hazardous. Also, as you know, the General Assembly has established a scientific committee to study this problem. This committee is due to report by July 1958, and its findings will no doubt be fully debated in the United Nations.5
We believe that nuclear tests can and should be suspended if other limitations of the type I have mentioned are agreed upon. Accordingly, the United States has joined with the Governments of the United Kingdom, France, and Canada in presenting proposals which provide for the suspension of testing in this context.6 Of special importance, I think, is the proposal that further production of fissionable materials for weapons purposes be stopped and a beginning be made in the reduction of existing weapons stockpiles. We believe that if this proposal is widely supported in the General Assembly, it will be accepted by the Soviet Union. In this event, we would be assured that atomic energy in the future would be devoted to peaceful purposes everywhere in the world.7 Sincerely