Partial Nuclear Test Ban Treaty
In 1979, the Defense Intelligence Agency (DIA) reported that the test might have been a Soviet test done in violation of the 1963 Partial Nuclear Test Ban Treaty (PTBT). Twenty years earlier in 1959, the USSR had conducted secret underwater tests in the Pacific in violation of the 1958 bilateral moratorium between the Soviet Union and the U.S. (cf. List of nuclear weapons tests of the Soviet Union) before the 1958 moratorium was unilaterally and officially abrogated by the Soviet Union in 1961.