The Cold War was a period of geopolitical tension between the United States and the Soviet Union from the late 1940s to the early 1990s. Strategies during this time included containment, aimed at preventing the spread of communism, and deterrence, which involved building up military capabilities to discourage aggression. Both superpowers engaged in proxy wars, supporting opposing sides in conflicts around the world, such as in Korea and Vietnam. Additionally, the arms race led to the development of nuclear weapons, creating a balance of power known as Mutually Assured Destruction (MAD), which aimed to prevent direct conflict.