The Cold War

The United States and the Soviet Union fought together against Nazi Germany, but they had very different systems: a capitalist democracy and a one-party communist state. As the war ended, the Soviets installed communist governments across Eastern Europe, and Western leaders came to see Soviet expansion as a threat.

In 1946 Winston Churchill said an iron curtain had descended across Europe. In 1947 President Truman announced that the United States would support countries resisting communist pressure, a policy known as containment, and the Marshall Plan offered large-scale aid to rebuild Western Europe.

Germany was split into a Western-aligned Federal Republic and a communist German Democratic Republic. When the Soviets blockaded West Berlin in 1948, the Western allies supplied the city by air for almost a year. The North Atlantic Treaty Organization was founded in 1949, and the Soviet-led Warsaw Pact followed in 1955.

In 1961 East Germany built the Berlin Wall to stop its citizens escaping to the West. It became the most recognisable symbol of the division of Europe.

The Soviet Union tested its first atomic bomb in 1949, ending the American monopoly. Both sides then developed hydrogen bombs and missiles able to strike each other's cities within minutes. The result was a doctrine often called mutually assured destruction: neither side could attack without being destroyed itself.

The closest call came in October 1962, when the United States discovered Soviet nuclear missiles in Cuba. After thirteen days of tension, the Soviets agreed to remove them, and the United States promised not to invade Cuba and privately agreed to withdraw its missiles from Turkey. A direct hotline between Washington and Moscow was set up afterward.

• Korean War, 1950 to 1953: North Korea, backed by China and the Soviet Union, fought South Korea and a US-led United Nations force; it ended in an armistice, not a peace treaty.
• Vietnam War: the United States fought to prevent a communist takeover of South Vietnam and withdrew in 1973; Saigon fell in 1975.
• Soviet-Afghan War, 1979 to 1989: Soviet forces fought Afghan resistance groups supported by the United States, Pakistan and others.
• Many conflicts in Africa, Latin America and Asia were shaped by superpower support for rival sides.

Competition extended into science and prestige. The Soviet Union launched Sputnik, the first artificial satellite, in 1957, and Yuri Gagarin became the first human in space in 1961. The United States answered with the Apollo programme, landing astronauts on the Moon in July 1969.

In the 1970s the superpowers pursued détente, an easing of tension, signing agreements to limit nuclear arms. Tension returned after the Soviet invasion of Afghanistan and during the early 1980s.

Mikhail Gorbachev became Soviet leader in 1985 and introduced glasnost, greater openness, and perestroika, economic restructuring. He reached arms control agreements with President Reagan and declined to use force to keep Eastern European regimes in power.

In 1989 communist governments fell across Eastern Europe, and on 9 November crowds began tearing down the Berlin Wall. Germany reunified in 1990. After a failed coup in August 1991, Soviet republics declared independence, and the Soviet Union was dissolved in December 1991, ending the Cold War.