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

Information on KGB counter-intelligence surveillance of Soviet tourists vacationing in other socialist countries who had contact with foreigners. The document states that Western intelligence services organized “friendship meetings” through tourist firms to meet Soviet citizens, gauge their loyalty to the USSR, and obtain political, economic, and military intelligence. KGB counter-intelligence paid particular attention to Soviet citizens who were absent from their groups, took side trips to different cities or regions, made telephone calls to foreigners, or engaged in “ideologically harmful” conversations in the presence of foreigners. Mirokhin regrets that the KGB underestimated the strengths and methodology of Western intelligence services. He concludes that the KGB should have adopted some of the same methods, and targeted Western tourists visiting socialist countries.