I am giving careful consideration to your communication of September 28th, and I am glad that we can continue to use this channel as a means of communicating privately and frankly.

I shall want to comment separately on other aspects of your letter, but because of the imminent discussions in the UN I want you to have my views promptly on the subject of nuclear testing. I believe that we are nearer to agreement on this issue than on others, and I believe that we should keep at it to see if we cannot promptly reach the understanding which the world wants and needs.
With respect to this topic, I am encouraged by the areas in which we are in accord and by your statement that the Soviet Union is prepared to make "new efforts" in order to conclude an early agreement. Certainly it would seem we are agreed in our approach to three types of tests--in the atmosphere, in outer space and under water.
With respect to underground tests, I am inclined to agree with you that the recent Pugwash conference of scientists brought forth some interesting suggestions, particularly those of British scientists Bullard and Penney. I must comment that we interpret those suggestions in somewhat different light than your letter indicates you do. Nonetheless the suggestions certainly are worthy of intensive development. The development of automatic unmanned seismic mechanisms might very well, if properly worked out, facilitate agreement on the means of actually detecting underground explosions--although my scientists indicate that it would require much more than the two or three such stations you mentioned as being located directly in the areas most frequently subjected to earthquakes. Of course, these mechanical devices would still have to be supplemented by a modest number of on-site inspections--for scientists agree that the data gathered by these machines would still leave doubt as to the cause of the explosion in a number of cases. Surely, considering the great value for international relations and the general security and tranquility of the world which the comprehensive agreement on the cessation of nuclear tests would entail, we can agree on the number of such inspections which would be necessary to identify the nature or cause of these explosions. Once that is done, with the number of unmanned stations worked out scientifically, and the method for international coordination established, we can conclude a treaty which will enable all peoples of the world to rest easier.
In the meantime, you suggest that the agreement we can more promptly reach on the cessation of tests in the atmosphere, in outer space and under water be accompanied by a five year moratorium on underground explosions. But surely it will not take five years to reach agreement--if agreement is ever to be reached--on banning underground tests, particularly in view of our mutual interest in the role of automatic seismic stations for detecting explosions. I would not feel justified in submitting to the Senate, moreover, a treaty on tests in other environments which would be discarded if agreement was not reached on testing under ground. It is nuclear explosions in the atmosphere, in outer space and under water which increase the percentage of fall-out and are the cause of grave concern to all peoples of the world. Such a treaty, in short, would be in itself a great step forward, both for humanitarian and political reasons.
So I continue to think that we are within striking distance of a treaty banning nuclear tests in the atmosphere, in outer space and under water. I believe we should try to work out such an agreement in time to meet the target day of January 1, 1963, and I think also that in the meanwhile we should be working intensively to make progress as rapidly as possible on the remaining problem of testing under ground. I believe that our negotiators should return to their labors in an intense effort to reach agreement on the questions that still divide us, and I hope very much that they will be able to make real and rapid progress in the meetings now scheduled to resume on November 12th.
JFK