What was the Cold War? The US-Soviet rivalry explained

The Cold War was the long rivalry between the United States and its allies and the Soviet Union and its allies, from roughly 1947 to 1991. It was "cold" because the two superpowers never fought each other directly. Instead they competed through an arms race, nuclear threats, wars fought by and through other countries, spying, propaganda and a race into space. It ended when the Soviet Union broke apart in December 1991.

In short

• The Cold War set two systems against each other: American-led capitalist democracies and Soviet-led communist one-party states.
• Nuclear weapons kept it cold between the superpowers, because a direct war could destroy both, but it was hot in places like Korea, Vietnam and Afghanistan.
• It ended without a war, as reform inside the Soviet Union, the revolutions of 1989 in Eastern Europe and the Soviet collapse in 1991 brought the rivalry to a close.

How did the Cold War start?

The United States and the Soviet Union were allies against Nazi Germany in World War II, but they had little in common beyond the enemy. The US was a capitalist democracy. The Soviet Union was a communist state run by one party under Joseph Stalin, which had lost something like 27 million people in the war and wanted friendly governments on its western border so it could never be invaded again. As Soviet forces stayed in Eastern Europe after 1945 and communist governments were installed in Poland, Hungary, Romania, Bulgaria and Czechoslovakia, Western leaders came to see expansion where Stalin saw security.

In March 1946, Winston Churchill told an audience in Fulton, Missouri, that "an iron curtain has descended across the continent". In 1947 the American diplomat George Kennan argued, in an anonymous article in Foreign Affairs, for a "long-term, patient but firm and vigilant containment of Russian expansive tendencies", in the words the US State Department's historians quote. Containment, stopping communism from spreading rather than rolling it back, became the core of US policy for four decades. That year President Harry Truman asked Congress for aid to Greece and Turkey and promised to support "free peoples" against outside pressure, a pledge known as the Truman Doctrine. The Marshall Plan followed, pouring American money into rebuilding Western Europe.

Who was on each side?

The world split into two blocs, with a large group of countries that tried to stay out of both.

	The Western bloc	The Eastern bloc
Leader	United States	Soviet Union
Military alliance	[[what-is-nato	NATO]], founded in 1949
Political system	Multi-party elections, in most members	One communist party in power
Economy	Mostly market economies	State ownership and central planning
Main allies	Western Europe, Canada, Japan, Australia	Eastern Europe; China until the Sino-Soviet split around 1960; Cuba from 1960
Divided country	West Germany	East Germany

Neither side was a single block in practice. France left NATO's military command in 1966, and communist China broke with the Soviet Union and later moved closer to the US in the 1970s. Many newly independent countries, led by India, Indonesia, Egypt and Yugoslavia, formed the Non-Aligned Movement to keep out of both camps.

Why did it never become a direct war?

The short answer is nuclear weapons. The US had used the atomic bomb on Japan in 1945, and the Soviet Union tested its first one in August 1949. Each side then built thousands more and the missiles and bombers to deliver them. By 1986 there were more than 60,000 nuclear warheads in the world, according to Our World in Data, and almost all of them were American or Soviet. Each side could destroy the other even after being attacked first, a condition known as mutually assured destruction, or MAD. That made a direct war look like suicide, and both sides took care to avoid one.

The closest they came was the Cuban Missile Crisis. On 14 October 1962, an American U-2 spy plane photographed Soviet nuclear missile sites being built in Cuba, 90 miles from Florida. President John F. Kennedy ordered a naval "quarantine" of the island on 22 October, and for a week the world waited. On 28 October, Soviet leader Nikita Khrushchev agreed to remove the missiles in return for a US pledge not to invade Cuba and, in secret, the removal of US missiles from Turkey, as the State Department's account records. Shaken, the two governments set up a direct "hotline" in 1963 and that year signed the Limited Test Ban Treaty, which banned nuclear tests in the atmosphere, in space and under water.

Where was the Cold War fought?

If the superpowers didn't fight each other, they fought through others. In these proxy wars, one or both of them armed, funded or sent troops to help one side of a local conflict.

• Korea, 1950–1953: communist North Korea, backed by the Soviets and joined by Chinese troops, invaded the South; a US-led United Nations force fought back, and the war ended in an armistice near the original border.
• Vietnam, 1955–1975: the US sent more than half a million troops at its peak to stop the communist North from taking the South, and withdrew; the Vietnam War ended with the North's victory in 1975.
• Afghanistan, 1979–1989: the Soviet Union invaded to prop up a communist government, and the US and others armed the Afghan resistance; Soviet troops left after ten years.
• Elsewhere: civil wars in Angola, Mozambique, Nicaragua and El Salvador; coups backed or encouraged by the US in Iran in 1953, Guatemala in 1954 and Chile in 1973; Soviet invasions that crushed reform in Hungary in 1956 and Czechoslovakia in 1968; and repeated crises over divided Berlin.

Millions died in these wars, most of them people of the countries where the fighting took place.

What was the space race?

The rivalry also played out in science, sport and culture, where each side tried to show its system worked better. The most famous contest was in space. The Soviet Union launched Sputnik, the first artificial satellite, on 4 October 1957, and the American shock led to the founding of NASA and new spending on science education. The Soviets also put the first person in orbit, Yuri Gagarin, on 12 April 1961. The United States answered with the Apollo program, which landed Neil Armstrong and Buzz Aldrin on the Moon in July 1969. The same rockets that carried satellites could carry nuclear warheads, so the space race was never only about exploration.

How did the Cold War end?

Tension eased and returned in waves. The 1970s brought détente, a relaxing of tension, with arms control treaties such as SALT I in 1972. The Soviet invasion of Afghanistan in 1979 and a new US arms buildup in the early 1980s chilled things again.

The end came from inside the Soviet bloc. Mikhail Gorbachev, who took power in 1985, tried to rescue a stagnant economy with reforms known as glasnost, or openness, and perestroika, or restructuring, and signed the 1987 treaty eliminating a whole class of medium-range nuclear missiles. Crucially, he chose not to send tanks when Eastern Europeans rose up in 1989. The Berlin Wall fell on 9 November 1989, communist governments across Eastern Europe were overthrown within months, and Germany reunified in October 1990. After a failed hard-line coup against Gorbachev in August 1991, most of the Soviet republics that had not already done so declared independence. Gorbachev resigned on 25 December 1991, and the Soviet flag was lowered over the Kremlin for the last time, as the State Department's history recounts.

Still argued

Historians still argue about who was to blame for the Cold War and why it ended. The early "orthodox" view held that Soviet expansion forced the West to respond. "Revisionist" historians in the 1960s and 1970s argued that American economic interests and atomic power pushed the Soviets into defensive hostility. "Post-revisionists" such as John Lewis Gaddis blended the two, and after Soviet archives opened in the 1990s, many put more weight on Stalin's own choices. On the ending, some credit Western pressure and the 1980s arms buildup, others Gorbachev's decisions and the Soviet economy's own failures; most see a mix.

The Cold War shaped the world that followed it, from NATO's membership to the nuclear arsenals that still exist, and it is one of the clearest cases of how history is argued over long after the events.

Check yourself

• Why did nuclear weapons make a direct war between the superpowers less likely, rather than more?
• What was containment, and how did the Truman Doctrine and the Marshall Plan put it into practice?
• What changed inside the Soviet bloc in the late 1980s that let the Cold War end without a war?

Sources

• Kennan and Containment, 1947 — Office of the Historian, US Department of State
• The Truman Doctrine, 1947 — Office of the Historian, US Department of State
• The Cuban Missile Crisis, October 1962 — Office of the Historian, US Department of State
• The Collapse of the Soviet Union — Office of the Historian, US Department of State
• Nuclear Weapons — Our World in Data
• A short history of NATO — NATO