The SALT II negotiations were opened at the end of 1972 and lasted seven years. A fundamental problem in these negotiations was the asymmetry between the strategic forces of the two countries, as the USSR had concentrated on missiles equipped with large warheads, while the United States had developed smaller missiles with greater precision. Questions were also raised about new technologies in development, definition questions and verification methods. Strategic Arms Limitation Talks (SALT), negotiations between the United States and the Soviet Union to limit the manufacture of strategic missiles capable of carrying nuclear weapons. The first agreements, known as SALT I and SALT II, were signed in 1972 and 1979 by the United States and the Union of Soviet Socialist Republics and aimed to limit the arms race of strategic (long-range or intercontinental) nuclear-armed ballistic missiles. For the first time proposed by U.S. President Lyndon B. Johnson in 1967, strategic arms limitation talks were agreed by the two superpowers in the summer of 1968, and in November 1969 comprehensive negotiations began. Nixon and Brezhnev seemed to be unlikely candidates for American and Soviet statesmen to sign a revolutionary arms limitation treaty. Both men had a reputation as hardened Cold War warriors.
Nevertheless, until 1972, the two heads of state and government sought to establish closer diplomatic relations between their respective nations. The Soviet Union was involved in an increasingly hostile war of words with Communist China; Border conflicts between the two nations had erupted in recent years. The United States sought help to free itself from the unpopular and costly war in Vietnam. Nixon, in particular, wanted to divert American public opinion from the fact that he had failed to end the conflict for nearly four years as president. The summit between Nixon and Brezhnev in May 1972 was a good time to follow the closer relations desired. The most important element of the summit was the salt agreements. Discussions on SALT have been going on for about two and a half years, but with little progress. However, during the meeting between Nixon and Brezhnev in May 1972, a monumental breakthrough was made. The SALT de accords signed on 27 May dealt with two important issues. First, they limited the number of anti-ballistic missile (ABM) sites to two.