May 13, 1959
Department of State Bureau of Intelligence and Research, Intelligence Information Brief No. 139, 'Disarmament Negotiations: The Fourth Power Problem: France'
According to intelligence reports, the French were trying to acquire from US firms the diagnostic technology needed to measure a nuclear explosion. INR did not believe that France had identified a specific test site and noted that France was under pressure to hold a test somewhere other than North Africa; nevertheless it went ahead with one in Algeria in early 1960.
May 22, 1963
Research Memorandum RFE-40 from Thomas L. Hughes to the Acting Secretary, 'A French Nuclear Testing Site in the Pacific? – Plans and Repercussions'
France’s staging of atmospheric and underground tests in Algeria became increasingly untenable when neighboring African countries protested and even temporarily broke diplomatic relations with Paris. Once Algeria became independent in 1962, French authorities made plans to develop a test site in Polynesia.