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

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.

With proliferation becoming a “greater threat to US interests over the next five years,” intelligence analysts believed that the “disruptive aspect of the proliferation phenomenon will constitute the greater threat to the United States.” While the estimators saw “low potential” for terrorist acquisition of nuclear weapons, the likelihood of terrorist/extortionist hoaxes was on the upswing. Significant portions of the NIE are excised, especially the estimate of Israel’s nuclear arsenal and its impact in the Middle East. Nevertheless, much information remains on the countries of greatest concern: Iraq and Libya in the Near East, India and Pakistan in South Asia, Brazil and Argentina in Latin America, and the Republic of South Africa, as well as those of lesser concern: Iran, Egypt, Taiwan and the two Koreas.