The draft statute prepared by the Naval General Staff in 1949 asked for four aircraft carriers of 20,000 tons to be available in two phases. At its meeting of 22 August 1949, the Supreme Council of the Navy was even more ambitious where they asked for a six aircraft carrier fleet. On 15 July 1952, the French Navy still wanted between two and five for the French Union (not available to the NATO). According to RCM 12, the final document of the Lisbon Conference of 1952, France should make available to NATO an aircraft carrier on D-day, two on day 30, three on day 180. However, by 1953, the Navy had to be satisfied with two aircraft carriers. The PA 54 "Clemenceau", budgeted in 1953, was delayed until November 1955, the PA 55 "Foch", budgeted for 1955, was delayed until February 1957. Between 1980 and 1981, she underwent a study to certify the platform before catapulting aircraft carrying missiles, bombs, AM-39 Exocet and tactical nuclear bombs. Both and underwent a modernization and refit, replacing 4 of their 8 100mm guns with 2 Crotale air-defense systems. In 1997, "Foch" also received 2 Sadral launchers (for 6 Mistral missiles each); those launchers were purchased by France in 1994.