The phrase "cold war" was introduced in its modern geopolitical sense by the British writer George Orwell in his essay "You and the Atom Bomb," published on October 19, 1945.¹⁰¹¹ Orwell foresaw a world dominated by two or three monstrous super-states possessing nuclear weapons, locked in a permanent "peace that is no peace" in which none could be conquered. The term entered political discourse on April 16, 1947, when American financier and presidential adviser Bernard Baruch, delivering a speech written by journalist Herbert Bayard Swope in South Carolina, declared that the United States was "in the midst of a cold war". Later that year, political commentator Walter Lippmann popularized the phrase through a syndicated newspaper series and book titled The Cold War: A Study in U.S. Foreign Policy.

Although the United States and the Soviet Union fought as allies during the Second World War, deep ideological mistrust predated the conflict, stretching back to the 1917 Bolshevik Revolution.¹² As the war in Europe neared its end, Allied leaders met at the Yalta Conference in February 1945 and the Potsdam Conference in July and August 1945 to determine the postwar settlement, particularly the administration of defeated Germany and the status of liberated Eastern Europe.¹³¹⁴ Soviet leader Joseph Stalin sought a buffer zone of friendly states along the western border of the Soviet Union to guard against future invasions, installing communist-dominated governments in Poland, Hungary, Romania, Bulgaria, and Albania.¹⁵¹⁶ U.S. President Harry S. Truman and British leaders viewed these actions as violations of wartime agreements guaranteeing free elections.

In February 1946, American diplomat George F. Kennan sent his "Long Telegram" from Moscow, arguing that the Soviet regime was inherently expansionist and had to be firmly contained by the West.¹⁷ Less than two weeks later, on March 5, 1946, former British Prime Minister Winston Churchill delivered a speech in Fulton, Missouri, stating that an "iron curtain" had descended across the European continent. When the United Kingdom informed Washington in February 1947 that it could no longer financially support the Greek government in its civil war against communist insurgents or aid Turkey against Soviet pressure, Truman addressed Congress on March 12, 1947. The resulting Truman Doctrine pledged American economic and military assistance to free nations resisting subjugation, formally inaugurating the policy of containment.

To prevent economic collapse in postwar Europe from fueling communist electoral gains, U.S. Secretary of State George C. Marshall proposed the European Recovery Program in June 1947.¹⁸ Known as the Marshall Plan, the initiative provided roughly 13 billion dollars in economic assistance to Western European nations over the next several years. Although offered to Eastern European states as well, Stalin forbade Soviet satellites from participating, viewing the program as an instrument of American economic imperialism. In February 1948, a communist coup d'état in Czechoslovakia eliminated the last non-communist government in the Soviet sphere.¹⁹

Germany became the focal point of the European division. After the Western Allies moved to introduce a new currency into their occupation zones to stabilize the economy, the Soviet Union imposed the Berlin Blockade in June 1948, cutting off all rail, road, and canal access to the Western-held sectors of Berlin, which lay deep inside the Soviet occupation zone.²⁰ Truman responded with the Berlin Airlift, during which American and allied aircraft flew food, fuel, and supplies into the city until the Soviets lifted the blockade in May 1949. Later that year, the Western zones were formally constituted as the Federal Republic of Germany (West Germany), and the Soviet zone became the German Democratic Republic (East Germany).

Military alliances soon institutionalized the partition of Europe. In April 1949, the United States, Canada, and ten Western European countries signed the North Atlantic Treaty, establishing the North Atlantic Treaty Organization (NATO) on the principle that an armed attack against one member would be considered an attack against all. Following the admission of West Germany to NATO in 1955, the Soviet Union and seven Eastern European satellite states—Albania, Bulgaria, Czechoslovakia, East Germany, Hungary, Poland, and Romania—established a counter-alliance, the Warsaw Pact.

The geopolitical balance shifted abruptly in late 1949. In August, the Soviet Union detonated its first atomic bomb, ending the American nuclear monopoly years earlier than Western intelligence had anticipated. In October, Chinese Communist forces under Mao Zedong defeated the Nationalist government of Chiang Kai-shek in the Chinese Civil War, proclaiming the People's Republic of China and signing a treaty of alliance with Moscow. In June 1950, North Korean troops backed by the Soviet Union and China invaded South Korea, triggering the Korean War. A United Nations coalition led by the United States intervened to defend the South, while Chinese forces entered the war as UN troops approached the Chinese border. The conflict ended in an armistice in July 1953, leaving the Korean peninsula divided near the 38th parallel and prompting a massive expansion of American defense spending and global military commitments.

Following the death of Joseph Stalin in March 1953, Nikita Khrushchev emerged as the leader of the Soviet Union.²¹ At the 20th Congress of the Communist Party in February 1956, Khrushchev denounced Stalin's purges and personality cult, initiating a policy of de-Stalinization and advocating "peaceful coexistence" with the West. The speech sparked upheaval in Eastern Europe; when reformist leader Imre Nagy attempted to withdraw Hungary from the Warsaw Pact during the Hungarian Revolution of October and November 1956, Soviet troops invaded Budapest and crushed the uprising. Ideological disagreements over de-Stalinization and relations with the West also fractured the communist bloc, leading to the Sino-Soviet split by the early 1960s, which turned China and the Soviet Union into rivals within the international communist movement.

By the late 1960s, the economic burden of the arms race, the Vietnam War, and internal bloc tensions prompted both superpowers to seek a relaxation of tensions, known as détente. In August 1968, Soviet and Warsaw Pact forces invaded Czechoslovakia to crush the "Prague Spring" reforms of Alexander Dubček, after which Soviet General Secretary Leonid Brezhnev proclaimed the Brezhnev Doctrine, asserting the right of the Soviet Union to intervene wherever socialist rule was threatened in the Eastern Bloc.³⁴ Despite this crackdown, diplomatic channels opened in Europe as West German Chancellor Willy Brandt pursued Ostpolitik, normalizing relations with East Germany, Poland, and the Soviet Union.³⁵

U.S. President Richard Nixon and his national security adviser Henry Kissinger leveraged the Sino-Soviet split by visiting Beijing in February 1972 to initiate the normalization of relations with the People's Republic of China. Three months later, in May 1972, Nixon met Brezhnev in Moscow to sign the first Strategic Arms Limitation Talks agreement (SALT I) and the Anti-Ballistic Missile (ABM) Treaty, which placed initial caps on strategic ballistic missile launchers and defensive interceptor systems. In July 1975, a joint American-Soviet spaceflight, the Apollo-Soyuz Test Project, symbolized scientific cooperation. The following month, thirty-five nations signed the Helsinki Accords, in which the West recognized the postwar borders of Central and Eastern Europe in exchange for Soviet commitments to respect human rights and fundamental freedoms—provisions that subsequently emboldened dissident movements such as Charter 77 in Czechoslovakia.³⁶³⁷

Détente unraveled in the late 1970s amid ongoing proxy struggles in Africa and Central America and disagreements over human rights.³⁸ Although U.S. President Jimmy Carter and Brezhnev signed the SALT II treaty in Vienna in June 1979, the Soviet Union invaded Afghanistan in December 1979 to prop up a faltering communist government against mujahideen insurgents. Carter withdrew SALT II from Senate ratification, imposed grain and technology embargoes on Moscow, organized a boycott of the 1980 Summer Olympics in Moscow, and authorized covert financial and military aid to the Afghan mujahideen.

The period of heightened hostility from 1979 to 1985 is often termed the "Second Cold War".³⁹ Taking office in 1981, U.S. President Ronald Reagan abandoned détente, increased American military spending, and denounced the Soviet Union in March 1983 as an "evil empire". Two weeks later, on March 23, 1983, Reagan announced the Strategic Defense Initiative (SDI), nicknamed "Star Wars," a research program aimed at creating a space-based missile defense shield.⁴⁰ Soviet leadership under Yuri Andropov viewed SDI and the concurrent NATO deployment of Pershing II intermediate-range missiles in West Germany as preparations for a preemptive nuclear strike.⁴¹ In November 1983, during the routine NATO command-post exercise Able Archer 83, Soviet intelligence briefly feared that the simulated nuclear countdown was a cover for an actual attack, placing Warsaw Pact air units on heightened alert until the exercise concluded.

When Mikhail Gorbachev became General Secretary of the Communist Party of the Soviet Union in March 1985, he inherited an economy crippled by structural inefficiency, falling oil revenues, technological lag behind the West, and the costly war in Afghanistan. To revitalize the socialist system, Gorbachev introduced two major domestic policies: perestroika (economic restructuring), which decentralized limited aspects of economic planning, and glasnost (political openness), which relaxed state censorship, permitted open debate on Soviet history and governance, and released political dissidents.

Recognizing that domestic reform required a reduction in military expenditures, Gorbachev pursued summit diplomacy with Reagan.⁴² Meetings in Geneva (1985) and Reykjavik (1986) led to the signing of the Intermediate-Range Nuclear Forces (INF) Treaty in Washington in December 1987, which eliminated an entire class of land-based nuclear and conventional missiles with ranges between 500 and 5,500 kilometers. In 1988, Gorbachev began withdrawing Soviet troops from Afghanistan—a process completed in February 1989—and announced at the United Nations significant unilateral reductions in Soviet conventional forces. Crucially, he repudiated the Brezhnev Doctrine, informing Eastern European leaders that Moscow would no longer use military force to keep communist governments in power.

Once the threat of Soviet intervention was removed, popular opposition swept across the Eastern Bloc during the Revolutions of 1989. In Poland, the independent trade union movement Solidarity negotiated semi-free elections in June 1989 and formed a non-communist coalition government. Hungary opened its border with Austria, allowing thousands of East Germans to flee West. Following weeks of mass protests in East German cities, East German authorities opened the crossing points of the Berlin Wall on the night of November 9, 1989, and citizens began dismantling the barrier.⁴³ Within weeks, the "Velvet Revolution" ended communist rule in Czechoslovakia, Bulgaria's leadership stepped down, and a violent uprising overthrew dictator Nicolae Ceaușescu in Romania. On December 2 and 3, 1989, Gorbachev and U.S. President George H. W. Bush met at the Malta Summit and declared an end to the ideological hostility between their nations; in October 1990, East and West Germany formally reunified.⁴⁴

Inside the Soviet Union, glasnost unleashed nationalist movements across the fifteen constituent republics, beginning in the Baltic states of Lithuania, Latvia, and Estonia, while economic disruptions worsened consumer shortages. In July 1991, the Warsaw Pact was formally dissolved, and Bush and Gorbachev signed the Strategic Arms Reduction Treaty (START I) to mandate deep cuts in deployed strategic nuclear warheads. In August 1991, Communist Party hardliners attempted a coup d'état against Gorbachev in Moscow to prevent the signing of a new union treaty decentralizing power to the republics. The coup collapsed after three days due to public resistance led by Russian President Boris Yeltsin, fatally undermining the authority of the Communist Party and the central Soviet government. One by one, the Soviet republics declared independence. Gorbachev resigned on December 25, 1991, and the Supreme Soviet formally dissolved the Soviet Union the following day, December 26, 1991, bringing the Cold War to a close.

Since the late 1940s, historians and political scientists have debated the origins of the Cold War, responsibility for its escalation, and the reasons for its conclusion.⁴⁵ In Western scholarship, three primary schools of interpretation emerged during the conflict. The "orthodox" or traditional school, prominent in the 1940s and 1950s and represented by scholars and policymakers such as Herbert Feis, Thomas A. Bailey, and George F. Kennan, attributed the breakdown of postwar peace to Joseph Stalin's ideological commitment to communist expansion and the subjugation of Eastern Europe, viewing American policies like the Truman Doctrine and Marshall Plan as necessary defensive responses.⁴⁶

During the 1960s and early 1970s, amid domestic criticism of the Vietnam War, the "revisionist" school challenged this consensus.⁴⁷ Historians including William Appleman Williams, Walter LaFeber, Gabriel Kolko, and Gar Alperovitz argued that the United States bore substantial responsibility for the conflict. Revisionists contended that after 1945 the Soviet Union was economically devastated and focused primarily on regional security, whereas American policymakers pursued an aggressive "open door" economic strategy aimed at integrating global markets under capitalist terms and used atomic diplomacy to intimidate Moscow.

In the 1970s and 1980s, a "post-revisionist" synthesis emerged, led by historians such as John Lewis Gaddis, Melvyn P. Leffler, Ernest R. May, and Marc Trachtenberg.⁴⁸⁴⁹ Drawing on newly declassified Western government documents, post-revisionists moved beyond assigning unilateral blame, arguing instead that the Cold War resulted from mutual misperceptions, security dilemmas, and competing geopolitical interests in the power vacuum left by the Second World War. Following the dissolution of the Soviet Union in 1991, the partial opening of Soviet, Chinese, and Eastern European archives enabled a new wave of scholarship—exemplified by historians such as Odd Arne Westad—that emphasized the ideological beliefs of Kremlin and Third World leaders and reframed the Cold War as a global struggle that reshaped postcolonial societies across Asia, Africa, and Latin America.

The Cold War left a lasting imprint on international politics, military infrastructure, and global culture. It left the United States as the world's sole superpower in the immediate post-1991 era, preserved institutional architectures such as NATO, and spurred technological innovations—including satellite communications, microelectronics, and the early internet—that originated in defense research. At the same time, Cold War interventions left enduring instability, unexploded ordnance, and authoritarian legacies in several developing countries, while the United States and the Russian Federation retained thousands of nuclear warheads as the principal inheritors of the superpower arms race.