The primary rivalry during the Cold War era was between the United States and the Soviet Union. This ideological, political, and military conflict spanned from the end of World War II in the late 1940s until the early 1990s, characterized by the struggle between capitalism and communism. Key events included the arms race, nuclear threats, proxy wars, and significant crises like the Cuban Missile Crisis. Both superpowers sought to expand their influence globally while avoiding direct military confrontation, resulting in a complex web of alliances and tensions, as well as significant cultural, technological, and espionage developments.