This lengthy report was State Department Bureau of Intelligence and Research's contribution to the first National Intelligence Estimate on the nuclear proliferation, NIE 100-6-57. Written at a time when the United States, the Soviet Union, and the United Kingdom were the only nuclear weapons states, the “Fourth Country” problem referred to the probability that some unspecified country, whether France or China, was likely to be the next nuclear weapons state. Enclosed with letter from Helmut Sonnenfeldt, Division of Research for USSR and Western Europe, to Roger Mateson, 4 June 1957, Secret

This estimate updates the 1974 predictions, and analyzes the “earliest dates of the technical feasibility of possession of a nuclear device” of the Republic of China, Pakistan, South Africa, The Republic of Korea, Argentina and Brazil, among others.

With the term “weapons of mass destruction” having not yet fully come into general usage, this NIE used the term “special weapons” to describe nuclear, biological, and chemical weapons (formerly the term “special weapons” was sometimes used to describe nuclear weapons only). With numerous excisions, including the names of some countries in the sections on “East Asia and the Pacific” and “Central America,” this wide-ranging estimate provides broad-brushed, sometimes superficial, pictures of the situations in numerous countries along with coverage of international controls to halt sensitive technology exports to suspect countries.

According to the 1985 report, the Argentines “have achieved at least a proof of principle of uranium enrichment via gaseous diffusion.” In other words, they had a workable system. Nevertheless, the enrichment plant would not be “fully operational until 1987-1988.” While the assessment of Argentine interest in nuclear weapons did not change, CIA analysts asserted that “Argentina continues to develop the necessary facilities and capabilities that could support a nuclear weapons development effort.”