Later, under the leadership of Leonid Brezhnev, Gromyko played a key role in the establishment of détente, a new phase of Soviet-American relations characterized by a significant reduction of tensions which lasted until 1979. In furtherance of this new arrangement, he oversaw the signing of the Treaty on the Non-Proliferation of Nuclear Weapons on 1 July 1968, the ABM and SALT I treaties in 1972, and the Agreement on the Prevention of Nuclear War in 1973. During his twenty-eight years as Minister of Foreign Affairs Gromyko supported the policy of disarmament, stating in his "Memoirs" that "Disarmament is the ideal of Socialism".