Nonproliferation talks entered their decisive phase after the submission of a joint U.S.-Soviet draft to the ENDC on February 21, 1967. One week later, High-Commissioner of the French Commissariat à l’énergie atomique, Francis Perrin, assessed France’s options. It was not “by accident,” he noted, the original five UN Security Council permanent members—the United States, the United Kingdom, France, the Soviet Union, and China—were in line for nuclear-club membership: “…they are the same profound reasons, of a geographical, demographic or other nature, which led to the choice [in 1945] … of the countries with special responsibilities in the maintenance of world peace.” After noting how advances in “India, Israel, Japan, Sweden, and also West Germany” portended the further spread of nuclear weapons—and acknowledging France had itself sought help with its weapon program—Perrin pondered whether proliferation might hasten nuclear disarmament by convincing the superpowers of its merits. In the end, however, fear of a “large and hostile” nuclear-armed PRC made him pessimistic. While he did not advise signing the NPT, it would be “very important” for France to affirm publicly, if unilaterally, “its constant policy since 1958 … not to cede any atomic weapon or any atomic explosive device to a country which does not possess it, and not to help any such country to manufacture them.” He dismissed internal opposition toward the NPT as defensive—"an a posteriori justification of the French decision to constitute an atomic armament." More significant was the likelihood West Germany would gain its own atomic arsenal, jeopardizing France’s “dominant political position among the Europe of the Six” members of the European Communities and reviving Cold War tensions in Europe. He finished with an eye-opening analysis of how the Kosygin proposal for nuclear-weapon states to extend negative security guarantees to non-nuclear-weapon states’ signatory to the NPT would not impede the use of French nuclear armaments against a West German blitzkrieg backed by the United States.

The French decision to join EURATOM was conditioned on the regional agency not impinging on national nuclear programs. As early as 1955, French Prime Minister Guy Mollet had instructed French negotiators that “Euratom will not be an obstacle toward the possible decision of France … to build nuclear weapons.”  While EURATOM’s jurisdiction would be limited to negotiating purchases of fissile materials, promoting trade with the United States and the United Kingdom, and exchanging reactors designs and civilian technology among members of the Atlantic community, Couve de Murville credited EURATOM with a fringe benefit: monitoring West Germany. In this spring 1960 letter to Prime Minister Michel Debré about revising the treaty, he warned against the removal of EURATOM controls over raw uranium and thorium or enriched uranium. Their removal, he cautioned, would create a dilemma: “either abandon the idea that German’s renunciation of atomic armaments could be enforced or support the enforcement of equivalent controls under the West European Union, which … would interfere in the direction of our programs and the development of our nuclear weapons.”

This Foreign Ministry analysis was written for French Foreign Minister Maurice Couve de Murville. It spells out the obstacles facing an independent deterrent two weeks after France’s first nuclear test on February 13, 1960. The author cautions that a “minor deterrent” of a few dozen 100-kilton atom bombs loaded on vulnerable, short-range Mirage IV A fighter-bombers would cost hundreds of billions of francs. Intermediate-range ballistic missiles with which to threaten Moscow would require an additional 8-10 years and a further cost of 500 billion francs (around $100 billion in 1960). In order to match the superpowers’ thermonuclear level, that figure could rise as a high as “several trillion” over more than a decade, during which time the United States and the Soviet Union might well leapfrog the French force de dissuasion.