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

The most recent CREST release included this analysis of “The Dynamics of Nuclear Proliferation: Balance of Incentives and Constraints.” The analyst sought to explain why “no additional overt proliferation of nuclear weapons has actually occurred” since the Chinese nuclear test, India had not weaponized while Israel and South Africa had not “taken any action to signal overt possession of nuclear weapons.”

This study begins, as the National Security Council requested, by assuming that the September 22, 1979 Vela event was a nuclear detonation. It discusses the possibility that the detonation could have occurred due to an accident, and noted the Defense Intelligence Agency’s suggestion that the Soviet Union might have had reasons to conduct a covert test in violation of its treaty commitments. But most of the study is concerned with other possibilities to explain the incident – a secret test by South Africa or Israel, or India, or Pakistan, or a secret joint test by South Africa and Israel. The 2004 version, in some instances, contains more information through page 10 than the 2013 version.

This study begins, as the National Security Council requested, by assuming that the September 22, 1979 Vela event was a nuclear detonation. It discusses the possibility that the detonation could have occurred due to an accident, and noted the Defense Intelligence Agency’s suggestion that the Soviet Union might have had reasons to conduct a covert test in violation of its treaty commitments. But most of the study is concerned with other possibilities to explain the incident – a secret test by South Africa or Israel, or India, or Pakistan, or a secret joint test by South Africa and Israel. The 2013 release (which is currently under appeal) includes some information from a “Secret Test by Others” (Pakistan, India) and the map on page 12 that had not been released before.

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.

This estimate updated an estimate (NIE-4-2-64) published in 1964 of the nuclear proliferation problem. That estimate, like this one, overestimated the likelihood of an Indian bomb, while somewhat underestimating Israel’s program. This assessment followed the same pattern—predicting India would produce a weapon within a “few years” and also putting Israel in the “might” category, although treating it as a “serious contender” nonetheless. Also following a short discussion of the “snowball effect” (later known as “proliferation cascades” or “chains”) suggesting that the United Arab Republic (Egypt-Syria) and Pakistan were likely to take the nuclear option should India or Israel go nuclear.

This NIE comes to the general conclusions that “there will not be a widespread proliferation of nuclear weapons over the next 10 years” and discusses programs in various countries (Israel, China, Sweden, India, West Germany, Japan, etc.) This copy includes newly declassified references to the Israeli nuclear weapons program, including the conclusion that “the Israelis, unless deterred by outside pressure, will attempt to produce a nuclear weapon some time in the next several years.”