The Cuban Missile Crisis of 1962 pushed the world to the brink of all-out nuclear war. Another step, and the world would have been destroyed. The US and the Soviet Union made the crisis an opportunity to begin reducing tensions. The Partial Nuclear Test Ban Treaty of 1963 and the installation of a "hotline" between the US and the Soviet Union were the starting points of this reduction.
On the other hand, the race to develop strategic weapons continued unabated. The US beefed up not only its strategic but its conventional weapon force. The Soviet Union worked on development and production of ICBMs and nuclear submarines.
Later, massive US spending on the Vietnam War, the Soviet Union's chronic economic stagnation and achievement of military parity with the US, intensification of the China-Soviet conflict, and rapprochement between the US and China moved the two countries towards signing the Nuclear Weapons Proliferation Prevention Treaty in 1968. Many disarmament treaties were subsequently signed, but none curbed the nuclear race in a substantial way. These treaties included the Treaty to Limit Antiballistic Missiles (ABM), the First Strategic Arms Limitation Treaty (SALT1), and the Treaty to Prevent War Between the US and the Soviet Union.
However, the danger of an outbreak of nuclear war between the two countries was heightened by the Soviet Union's military intervention in Afghanistan, deployment of US and Soviet theater nuclear missiles, and deployment of US cruise missiles in Europe. In 1981, the US and the Soviet Union began negotiations on reducing their intermediate nuclear forces in Europe (INF), and in 1982 the Strategic Arms Reduction Talks (START) began. These talks made no real progress.
In 1985 Mikhail Gorbachev became the Secretary of the Communist Party in the Soviet Union. When his "perestroika" became Soviet policy, the Soviet Union and the US renewed disarmament negotiations, and in 1987 the INF Treaty eliminated intermediate and short-range missiles. The missiles covered under the treaty represented only a small percentage of the total nuclear weapons in existence, but as the first treaty to actually reduce nuclear weapons, it was a watershed event.
Even at the Warsaw Pact Summit Conference, Gorbachev expressed respect for the independence and rights of various nations and recognized anew the principle of national sovereignty. Communist states began to break up in the Soviet Union and various other Eastern Europe countries. In 1989, the Berlin Wall, an important symbol of the East-West stand-off, came down.
Against this historical background, in 1989 President Bush and Secretary Gorbachev held a US-Soviet summit, at which they proclaimed that the Cold War, which had controlled world politics since the end of the Second World War, was over. At the same time they recognized that US-Soviet relations were moving into a new stage. The next year, 1990, the 22 countries of the North Atlantic Treaty Organization (NATO), and the Warsaw Pact also declared the Cold War over. From around 1991, democratization in Eastern Europe, the dissolution of the Soviet Union, and the unification of East and West Germany all contributed to the continuing disintegration of communist systems; the Cold War structure had truly collapsed.