With a nuclear nonproliferation treaty under consideration in Washington, INR considered which countries were likely to sign on and why or why not. INR analysts, mistakenly as it turned out, believed it unlikely that the Soviet Union would be a co-sponsor of a treaty in part because of the “international climate” and also because Moscow and Washington differed on whether a treaty would recognize a “group capability.”

An intelligence report that the fuel core of the Canadian-Indian Reactor (CIR) at Trombay was being changed every six months raised questions about India’s nuclear objectives: a six-month period was quite short for “normal research reactor operations,” but it was the optimum time for using the CIR’s spent fuel for producing weapons grade plutonium. According to INR, India had taken the “first deliberate decision in the series leading to a nuclear weapon,” which was to have “available, on demand, unsafeguarded weapons-grade plutonium or, at the least, the capacity to produce it.”

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).