In the context of the Cold War, the lessening of tensions between the East and West, along with domestic reform in the Soviet Union, worked together to achieve the end of communism in Eastern Europe and eventually the Soviet Union altogether.
The term is most often used in reference to a period of general easing of the geo-political tensions between the Soviet Union and the United States; it was the distinct lessening of the Cold War. It began in 1969, as a core element of the foreign policy of U.S. president Richard Nixon, in an effort to avoid the collision of nuclear risks. The Nixon administration promoted greater dialogue with the Soviet government, including regular summit meetings and negotiations over arms control and other bilateral agreements. Détente was known in Russian as разрядка ("razryadka", loosely meaning "relaxation of tension").
The period was characterized by the signing of treaties such as SALT I and the Helsinki Accords. Another treaty, START II, was discussed but never ratified by the United States. There is still ongoing debate amongst historians as to how successful the détente period was in achieving peace.
After the Cuban Missile Crisis of 1962, the two superpowers agreed to install a direct hotline between Washington D.C. and Moscow (the so-called red telephone), enabling leaders of both countries to quickly interact with each other in a time of urgency, and reduce the chances that future crises could escalate into an all-out war. The U.S./U.S.S.R. détente was presented as an applied extension of that thinking. The SALT II pact of the late 1970s continued the work of the SALT I talks, ensuring further reduction in arms by the Soviets and by the U.S. The Helsinki Accords, in which the Soviets promised to grant free elections in Europe, has been called a major concession to ensure peace by the Soviets.
Détente ended after the Soviet intervention in Afghanistan, which led to the United States boycott of the 1980 Olympics in Moscow. Ronald Reagan's election as president in 1980, based in large part on an anti-détente campaign, marked the close of détente and a return to Cold War tensions. In his first press conference, President Reagan said "Détente's been a one-way street that the Soviet Union has used to pursue its aims."