440. Memorandum of Conference with the President1
OTHERS PRESENT
- Dr. Killian
- General Goodpaster
Dr. Killian said that further study had disclosed possible ways of decoupling a seismic signal from an atomic explosion. The use of large cavities would be a way of doing this. For each kiloton of yield a cavity of about 100,000 cubic meters (i.e., about 100 feet in radius) would be required. From the standpoint of monitoring, this presents a very real loophole, in that it becomes difficult to set any kind of a threshold for detectable tests. Accordingly, agreements to suspend testing in the atmosphere, and to limit testing to explosions outside the atmosphere, would seem to be indicated.
It is also technically possible to conduct weapons tests in outer space out to about 180 million miles. Conceivably a satellite detection system could be established that would be capable of detecting unshielded tests out to that distance, but this could be countered by shielding of weapons with lead shields that would prevent detection of tests up to several hundreds of kilotons.
In summary, a system with a low threshold cannot be guaranteed.
The President said he may want to have a session of a couple of hours’ duration with Macmillan here next week. He would want Dr. Killian to come up by helicopter.
The President added that he takes with some seriousness Khrushchev’s statement that the Soviets are not testing small weapons. He added that this is being carefully studied at his request.
Dr. Killian said that if the Geneva talks should be recessed for political reasons, there are technical reasons supporting a decision to leave open the possibility of exploring techniques of monitoring and [Facsimile Page 2] inspection, and in particular to see if agreement can be reached on conducting some tests to observe their effects and detectability.
Brigadier General, USA
- Source: Technical aspects of detecting nuclear testing. Secret. 2 pp. Eisenhower Library, Whitman File, DDE Diaries. Drafted on March 17.↩