Détente and the outbreak of the Second Cold War

History · A Level: The end of the Cold War, 1975-1991 (exams to Nov 2026). The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.

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The idea

Détente was the relaxing of tension between the superpowers in the 1970s. It produced arms agreements, trade and, in 1975, the Helsinki Final Act, signed by 35 states.

It faded in the later 1970s. Many in the USA believed the USSR was using détente to gain ground: it backed forces in Angola and Ethiopia, deployed SS-20s and ignored human rights promises. Carter's criticism of Soviet human rights angered Moscow.

The Soviet invasion of Afghanistan in December 1979 ended détente. Carter imposed sanctions, and Reagan, president from 1981, raised defence spending and used hard language. This period is called the Second Cold War.

Rules to remember

August 1975 Helsinki Final Act: the West accepted the post-war borders in Europe; the East promised to respect human rights.
Dissident groups such as Charter 77 in Czechoslovakia later used the human rights promises against their governments.
December 1979: Soviet troops invaded Afghanistan to support its communist government.
US response: SALT II withdrawn from the Senate, grain embargo, boycott of the 1980 Moscow Olympics.
January 1980 Carter Doctrine: the USA would use force to defend the Persian Gulf.
March 1983: Reagan called the USSR an 'evil empire' and announced SDI.
September 1983: a Soviet fighter shot down Korean Air Lines flight 007. 1984: Soviet boycott of the Los Angeles Olympics.

Common mistake

Do not say the invasion of Afghanistan alone caused the end of détente. Détente was already weak by 1979. Afghanistan was the final blow, not the only cause.

Worked example

Why did the Helsinki Final Act turn out to help the West more than Soviet leaders expected?

Brezhnev valued the recognition of borders, which made Soviet gains of 1945 seem secure.
In return the USSR signed promises on human rights that it did not intend to keep.
Groups in the East and Western governments then quoted these promises to criticise communist rule.

Answer: The human rights section gave dissidents and the West a standard to hold communist governments to, which weakened those governments over time.

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