The Cold War was a period of geopolitical tension between the United States and the Soviet Union and their respective allies, lasting from approximately 1947 to 1991. It was characterized by ideological competition between liberal democratic capitalism and Marxist-Leninist communism, an arms race including nuclear weapons, competition for influence in developing nations, and a series of proxy conflicts - but no direct large-scale military engagement between the two superpowers. The term “cold” distinguishes it from a “hot” war involving open armed conflict between the principal parties. The conventional start date is 1947, though some historians place the origin as early as 1945; the conventional end date is the dissolution of the Soviet Union on 26 December 1991, though others mark it at the fall of the Berlin Wall on 9 November 1989. For a detailed account of events, see Cold War - History.

The Cold War emerged from the aftermath of World War II, during which the United States and Soviet Union had been allied against Nazi Germany. As the war ended, fundamental disagreements over the postwar order - including the political status of Eastern Europe, the division of Germany, and nuclear weapons - produced a rapid deterioration in relations. The United States announced the Truman Doctrine in 1947, committing to containing Soviet expansion, while the Soviet Union consolidated control over Eastern Europe through satellite states. The two blocs divided much of the world into competing spheres of influence.

Arms race: Both superpowers developed and stockpiled nuclear weapons on a scale capable of mutual assured destruction (MAD). The arms race extended to conventional forces, delivery systems, and eventually space technology.

Proxy conflicts: Direct confrontation was avoided, but both powers supported opposing sides in conflicts across Korea, Vietnam, Angola, Afghanistan, Latin America, and elsewhere. These wars produced substantial casualties and long-term regional instability.

Ideological competition: Each side promoted its political and economic system as a model for developing nations. This competition operated through diplomacy, foreign aid, propaganda, covert action, and cultural exchange programs.

Alliance structures: The United States led the NATO alliance in Western Europe; the Soviet Union led the Warsaw Pact in Eastern Europe. Non-aligned nations, organized in part through the Non-Aligned Movement, attempted to avoid incorporation into either bloc.

Détente and escalation cycles: The Cold War passed through phases of heightened tension - the Berlin Crises, the Korean War, the Cuban Missile Crisis of 1962 - and phases of reduced tension, including the détente period of the 1970s under Nixon and Brezhnev.

The Cold War ended with the collapse of communist governments across Eastern Europe in 1989 and the dissolution of the Soviet Union in 1991. The causes of this collapse are themselves a subject of historical debate. Contributing factors identified by various analysts include internal economic stagnation in the Soviet system, the costs of the Afghan war, nationalist movements within Soviet republics, the reform programs of Mikhail Gorbachev (glasnost and perestroika), and sustained Western pressure including the military buildup of the Reagan administration. How much weight to assign each factor is contested. See Cold War - End Debate.

There is broad scholarly consensus on the basic factual sequence of events. Interpretive questions - including which party bears greater responsibility for the conflict's origins, whether it was inevitable, and what caused its end - remain actively debated among historians. See Cold War - Historiography Consensus.

Orthodox (Western): The Cold War was primarily a response to Soviet expansionism and the inherent aggressiveness of Marxist-Leninist ideology. Western policy, including containment, NATO, and eventual military buildup, successfully defended liberal democracy and ultimately produced Soviet collapse. See Cold War - Orthodox Viewpoint.

Soviet and Marxist-Leninist: The Cold War was driven by capitalist encirclement - Western hostility toward the world's first socialist state, fear of communist example, and American imperial ambition. Soviet policy was fundamentally defensive. See Cold War - Soviet/Marxist-Leninist Viewpoint.

Revisionist: American economic interests, ideological rigidity, and foreign policy decisions - including the Truman Doctrine and early atomic diplomacy - bear substantial responsibility for initiating and sustaining the conflict. Associated with historians including Gar Alperovitz and William Appleman Williams. See Cold War - Revisionist Viewpoint.

Post-revisionist: Neither superpower was solely responsible; both pursued national interests in a context of genuine mutual misperception and structural incentives toward rivalry. Associated with historians including John Lewis Gaddis. See Cold War - Post-Revisionist Viewpoint.

Third World and Non-Aligned: The Cold War, as experienced outside the two blocs, was a period of superpower interference, proxy warfare, and constrained sovereignty. Non-aligned nations attempted to navigate between the blocs while pursuing their own development. See Cold War - Non-Aligned Viewpoint.

• Cold War - History
• Cold War - Debate
• Cold War - End Debate
• Cold War - Historiography Consensus
• Containment
• Nuclear Deterrence
• Proxy War
• Non-Aligned Movement
• Détente
• Soviet Union
• Truman Doctrine
• Marshall Plan

1. Gaddis, John Lewis. The Cold War: A New History. Penguin Press, 2005.
2. Leffler, Melvyn P. A Preponderance of Power: National Security, the Truman Administration, and the Cold War. Stanford University Press, 1992.
3. Westad, Odd Arne. The Global Cold War: Third World Interventions and the Making of Our Times. Cambridge University Press, 2005.
4. Alperovitz, Gar. Atomic Diplomacy: Hiroshima and Potsdam. Simon & Schuster, 1965.
5. Williams, William Appleman. The Tragedy of American Diplomacy. World Publishing, 1959.
6. Service, Robert. Comrades: A History of World Communism. Harvard University Press, 2007.
7. Zubok, Vladislav M. A Failed Empire: The Soviet Union in the Cold War from Stalin to Gorbachev. University of North Carolina Press, 2007.