The first part of this document is a letter from the FCO's Paul Lever to Bryan Cartledge, in which Lever details his thoughts on Prime Minister Begin's recent letter to Prime Minister Thatcher. The second part are speaking notes prepared for Thatcher, in preparation for her upcoming meeting with Begin (scheduled for May 23,1979, the day after Lever sent this letter.)

Memorandum with a briefing on both the Pakistani and Israeli nuclear positions and suggestions for a response to the letter from Menachem Begin.

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.

Just a few months into President Reagan’s first term his administration wanted to make its own mark on nonproliferation policy. The report suggests building “broader bilateral relationship[s]” and offering political and security incentives could persuade states considering developing nuclear weapons to cease these efforts.