Final answer:
Ideological differences between the United States and the Soviet Union led to the Cold War, a long-standing conflict characterized by competition for supremacy in various aspects.
Step-by-step explanation:
Ideological differences between the United States and the Soviet Union led to the Cold War. The Cold War was a decades-long conflict between these two superpowers, characterized by the competition for ideological, social, economic, technological, and military supremacy. It involved proxy wars and an arms race, including the development of nuclear weapons. The United States aimed to contain the spread of communism, while the Soviet Union sought to expand its influence.