56 years ago today, November 17, 1969 (October 8, 1969 in the lunar calendar), the United States and the Soviet Union began the first phase of strategic arms negotiations. The first phase of negotiations was from November 17, 1969 to May 27, 1972. Representatives of both sides held 123 plenary meetings. After fierce bargaining, they finally signed an interim agreement on certain measures to limit offensive strategic weapons. The interim agreement lasted for five years and froze the land-based intercontinental missiles of both sides at the level of July 1, 1972, that is, 1618 for the Soviet Union and 1054 for the United States; Freeze the submarine-launched missiles and missile nuclear submarines of both sides at the level of actual and under construction on May 26, 1972, that is, 950 and 62 in the Soviet Union, and 710 and 44 in the United States; No restrictions are imposed on the strategic bombers of both sides. This is to freeze the development of the quantity of their offensive strategic weapons while both sides have a "sufficient sense" of the quantity of their offensive strategic weapons and turn the nuclear arms race into a direction dominated by improving quality. For the Soviet Union, the interim agreement allowed it to maintain its advantage over the United States in terms of quantity of offensive strategic weapons in order to concentrate its efforts to catch up with the United States in terms of quality. For the United States, since it had effectively stopped increasing the number of its offensive strategic weapons at that time, it was clearly in the interest of the Interim Agreement to limit the growth of the Soviet Union's offensive strategic weapons, especially the giant SS-9 missile. The qualitative advantage of U.S. weapons at the time was enough to offset the Soviet Union's quantitative advantage. The interim agreement did not touch a single hair on both sides 'nuclear arsenals, but only set a rule for the subsequent nuclear race. In addition, in view of the fact that both the United States and the Soviet Union felt that anti-missile defense systems were expensive and their effectiveness was questionable at that time, and neither side was prepared to develop them in large quantities, they reached the Treaty on the Limitation of Anti-Missile Defense Systems, in which both sides maintained two anti-missile defense systems. From November 21, 1972, the United States and the Soviet Union began the second phase of negotiations in Geneva. The negotiations lasted for seven years and held about 300 plenary meetings. Finally, on June 18, 1979, Carter and Brezhnev signed the Second Strategic Arms Reduction Treaty in Vienna. The treaty was valid until 1985 and determined that the total limit of strategic weapons of both parties was 2250, of which the limit for split-guided multiple warhead delivery vehicles was 1320. Like the interim agreement, the treaty is still limited to quantity and without quality, and the quota for split-guided multi-warhead missiles is higher than the number currently available by both parties at the time, leaving room for further increases in quantity. Some U.S. military strategy experts pointed out that the treaty is unfavorable to the United States: it allows the Soviet Union to deploy 308 heavy missiles, whose destructive power exceeds the total destructive power of the United States 'existing intercontinental missiles; The Soviet Union's backfire bombers are not counted as strategic weapons and are not included in the total quota, while the United States 'airborne cruise missiles are restricted as split-guided multi-warhead strategic weapons; the total number of strategic weapons and the quota for split-guided multi-warhead missiles are on the high side, which will help the Soviet Union leverage its advantages of large number and high throw weight of intercontinental missiles, and meet the Soviet Union's need to accelerate the deployment of split-guided multi-warhead missiles. According to the U.S. Constitution, treaties require two-thirds approval by the Senate before they can enter into force. Due to insufficient support votes, Congress postponed debate and vote on the treaty during the Carter administration. After taking office, Reagan believed that the treaty had "fatal shortcomings" and opposed congressional approval. At the same time, strategic arms negotiations stalled due to tensions between the United States and the Soviet Union.