65. Aide-Mémoire From the Soviet Embassy to the Department of State1

No. 3

According to Associated Press Agency reports, a nuclear rocket engine of the “Kiwi” type, which is a prototype of engines for space ships, was exploded for experimental purposes on January 12 of this year in the U.S.A. The purpose of this experiment, as the Agency points out, was to establish what might occur in case of an accident during the launching of a rocket with nuclear fuel. As an Associated Press correspondent reports, there occurred as a result of the explosion “a tremendous cloud of dust and a flash of light which blocked the sun” for some time. Judging by the report of this Agency, published prior to the experiment, the self-generating explosion of the nuclear rocket engine must have been accompanied by the dissemination of radioactive particles from the explosion over a large distance.

In connection with this the Soviet Government cannot but come to the conclusion that if these reports of the Associated Press Agency about the nuclear explosion which has been conducted conform to reality, then there has taken place a violation by the United States of the “Treaty Banning Nuclear Weapons Tests in the Atmosphere, in Outer Space and Underwater,” signed in Moscow on August 5, 1963, and which entered into force October 10 of that year. As is known, in point 1, Article I, of the cited treaty it is stated that each of its participants “undertakes to prohibit, to prevent, and not to carry out any nuclear weapon test explosion, or any other nuclear explosion, at any place under its jurisdiction or control,” in the atmosphere, in outer space and underwater.

Considering the full seriousness of the situation which can arise in the case that there really took place a nuclear explosion falling under the prohibition stipulated by the treaty on the prohibition of nuclear weapons tests, the Soviet Government expects that the Government of the U.S.A. will give the necessary clarifications regarding the character of the experiment carried out in the U.S.A. on January 12 of this year.

  1. Source: Johnson Library, National Security File, Subject File, Nuclear Testing—USSR, Vol. I, Box 31. No classification marking. In a January 22 telephone call to Seaborg, Foster said that Dobrynin made this oral reply to Thompson at 3:15 p.m. the same day. (Seaborg, Journal, Vol. 10, p. 87) Dobrynin handed the aide-mémoire to Thompson, saying it was not related to the inquiry Secretary Rusk had made of him concerning the Soviet test on January 15. When Thompson responded that he hoped there was no relationship between the two inquiries, Dobrynin “said he thought that in fact there may have been some similarity between the two events in that both may have been accidents.” (Memorandum of conversation, January 22; ibid., p. 89)