The Cold War (Russian: холо́дная война́, kholodnaya voĭna) was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States and its NATO allies. Both sides possessed nuclear weapons, and because their use would probably guarantee their mutual assured destruction the chief military forces never engaged in a major battle with each other. The nuclear deterrent kept the war 'cold.' The conflict was expressed through military coalitions, strategic conventional force deployments, extensive aid to states deemed vulnerable, proxy wars, espionage, propaganda, conventional and nuclear arms races, appeals to neutral nations, rivalry at sports events, and technological competitions such as the Space Race. The antagonistic behaviour that both sides displayed towards their enemy resulted in many crises which risked mutual annihilation in a nuclear exchange. To alleviate thie risk of nuclear war exacerbated by accident or mistake, both sides sought détente to relieve political tensions and deter direct military attack.