Concerns about the credibility of US nuclear deterrence generated Supreme Allied Commander Europe (SACEUR) General Lauris Norstad’s proposal for a NATO-controlled medium-range ballistic missile (MRBM) force. This lengthy report represented INR’s assessment of “present and future European interest in national or multinational nuclear weapons capabilities,” including the MRBM proposal, and the extent to which an “enhancement of NATO's nuclear role” could “deter national or multinational European nuclear weapons programs.”

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

Sonnenfeldt summarizes various recent types of military cooperation between the United States and France. These include cooperation on contingency plans for dealing with Germany and US nuclear assistance to France. He suggests that it is time to define the "political philosophy underlying these disparate measures of cooperation."