Détente (English spelling) French

It refers to the easing of tensions in international relations, but in the history of international politics it refers to the reconciliation between the United States and the Soviet Union in the 1970s and the resulting realization of East-West cooperation in Europe. With the exception of the period around the Geneva Summit of the Four Great Powers in 1955, US-Soviet relations after World War II remained in a state of tension due to the missile race in the late 1950s, the shooting down of a U-2 jet in 1960, and the Cuban Missile Crisis in 1962. However, around this time, France and China began to rebel against the US-Soviet bipolar dominance, and the US became bogged down in the Vietnam War, while the Soviet Union also faced the Sino-Soviet conflict, causing the US and Soviet dominance within the two major camps to crumble. As a result, the United States and the Soviet Union rapidly moved toward reconciliation following the signing of the Partial Nuclear Test Ban Treaty in 1963, and an unexpected cooperative relationship developed in the form of the Nuclear Non-Proliferation Treaty in 1968, the start of the U.S.-Soviet Strategic Arms Reduction Talks (SALT) in 1970, U.S. President Nixon's visit to the Soviet Union and the signing of the SALT-I agreement in 1972, and Soviet General Secretary Brezhnev's visit to the United States and the signing of the Agreement to Prevent Nuclear War in 1973.

In response to these circumstances, a detente also developed in Europe, with the conclusion of a non-use of arms treaty between the Soviet Union and West Germany and a normalization treaty between Poland and West Germany in 1970, and the Treaty on Basic Relations between East and West Germany, which had been in conflict since the end of the war, being signed in 1972, and both countries achieving simultaneous membership in the United Nations in 1973. Thus, the detente between the United States and the Soviet Union and the reconciliation between Eastern and Western Europe culminated in the holding of the Conference on Security and Cooperation in Europe in Helsinki in 1975 and the signing of the second SALT Agreement between the United States and the Soviet Union in 1979. However, relations between the United States and the Soviet Union deteriorated again in the 1980s (the second Cold War), putting an end to the détente of the 1970s.

[Shunichi Fujimura]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

国際関係における緊張緩和のことをいうが、国際政治史のうえでは1970年代の米ソ（アメリカとソ連）の和解と、それに伴うヨーロッパでの東西協調の実現のことをさす。第二次世界大戦後の米ソ関係は1955年のジュネーブ四大国首脳会談前後を例外として、1950年代後半のミサイル競争、1960年のU‐2型機撃墜事件、1962年のキューバ危機と緊張状態が続いた。しかしこのころからフランス、中国が米ソ二極支配に反発、加えてアメリカはベトナム戦争の泥沼化で、またソ連も中ソ対立によって、それまでの二大陣営内の米ソの優位が崩れた。このため米ソは1963年の部分的核実験停止条約の調印を機に急速に和解に向かい、1968年の核不拡散条約、1970年の米ソ戦略兵器削減交渉（SALT）の開始、1972年のニクソン米大統領の訪ソとSALT‐Ⅰ協定の調印、1973年のブレジネフ・ソ連書記長の訪米と核戦争防止協定の調印という形で、予期せぬ協調関係が展開した。

　こうした情勢を受けてヨーロッパにも緊張緩和が醸成され、1970年にソ連・西ドイツ間の武力不行使条約とポーランド・西ドイツ間の国交正常化条約が成立、また戦後対立が続いていた東西ドイツ間にも1972年に国家関係基本条約が調印され、両国は1973年国連同時加盟を実現した。こうして米ソの緊張緩和と東西ヨーロッパの和解は1975年のヘルシンキにおける全欧安保協力会議の開催と1979年の米ソ第二次SALT協定の調印で最高潮に達した。しかし1980年代に入るとふたたび米ソの関係は悪化し（第二次冷戦）、1970年代のデタントに終止符が打たれた。

［藤村瞬一］

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