The Cold War was a prolonged period of military competition and tension between the US and which nation?

The Cold War was primarily a period of military competition and tension between the United States and the Soviet Union. This rivalry, which lasted from the late 1940s until the early 1990s, encompassed political, ideological, and economic conflicts, as well as numerous proxy wars. The two superpowers sought to expand their influence globally, leading to a significant arms race and the eventual dissolution of the Soviet Union in 1991.