National Intelligence Estimate NIE 4-63, 'Likelihood and Consequences of a Proliferation of Nuclear Weapons Systems'

This US analysis of the likelihood of nuclear proliferation during the next decade was finished only days after the first Chinese nuclear test on 16 October. The report analyses the implications of this test, as well as programs in India, Israel, Sweden, West Germany, Italy, Japan, Canada, and others. The National Intelligence Estimate (NIE) argued that India was the only new state likely to develop nuclear weapons, concluding that “there will not be a widespread proliferation …over the next decade.”

Noting new intelligence information on the Indian and Israeli nuclear programs, as well as the possibility of developments concerning Sweden, Hughes requested McCone to initiate a new estimate of nuclear proliferation trends, which would eventually become part of a October 1964 National Intelligence Estimate (NIE). Hughes enclosed draft “terms of reference,” that included questions about the possibility of “clandestine” weapons programs and new technological developments that could make weapons development “easier” (perhaps a reference to gas centrifuge technology that the 1964 NIE would discuss).