The Cold War, which lasted from the end of World War II until the early 1990s, was primarily driven by ideological, political, and strategic differences between the United States and the Soviet Union. Several key factors contributed to the onset and persistence of the Cold War:

1. **Ideological Conflict:** The Cold War was fundamentally a clash between capitalism, as represented by the United States, and communism, as represented by the Soviet Union. The U.S. championed a capitalist democracy with market economies and individual freedoms, while the USSR promoted a communist ideology with state-controlled economies and a single-party political system.

2. **Power Vacuum After WWII:** The end of World War II left a power vacuum in Europe and other parts of the world. Both superpowers emerged from the war as dominant military and political forces, but with conflicting visions for the post-war order. The Soviet Union sought to expand its influence over Eastern Europe and promote communist governments, while the U.S. aimed to prevent this expansion and promote democratic governance and free-market economies.

3. **Nuclear Arms Race:** The development and stockpiling of nuclear weapons by both superpowers created a precarious balance of power known as mutually assured destruction (MAD). The fear of nuclear war and the desire to maintain strategic superiority fueled intense competition and espionage.

4. **Economic and Military Competition:** The U.S. and the Soviet Union engaged in a global competition for influence, including in regions like Asia, Latin America, and Africa. This competition often manifested through proxy wars, economic aid programs, and military alliances, such as NATO and the Warsaw Pact.

5. **Mutual Distrust and Misunderstandings:** Both superpowers had deep-seated distrust of each other’s intentions. The U.S. feared the spread of communism and totalitarianism, while the Soviet Union viewed Western efforts as attempts to undermine its security and socialist system.

Overall, the Cold War was characterized by a complex interplay of ideological conflict, strategic competition, and mutual suspicion, which defined international relations for nearly half a century.