Why did great tension exist between the USA and USSR after WWII?

The USSR aspired to conquer most of Europe, the Middle East, and the Far East, including Korea, and thought that the world should become entirely communist.

The US feared the USSR's territorial ambitions and felt that the world should become fully democratic with a capitalist economy.

The rival territorial ambitions brought these ideological differences to a boiling point, and these opposing worldviews guaranteed tension between the USSR and the US.

The Truman Doctrine and Marshall Plan attempted to contain communism and oppose the territorial ambitions of the USSR. Warfare between client states in the Middle East and Korea was a result of the tensions. The USSR installed puppet governments throughout their areas of control in Eastern Europe.

Tension between the USSR and the US led to the cold war and MAD Mutually Assured Destruction.

Great tension existed between the USA and the USSR after World War II primarily due to ideological differences, territorial ambitions, and the desire for global influence. The USA, advocating for capitalism and democracy, viewed the spread of communism as a threat to its interests and the stability of the world order. On the other hand, the USSR aimed to expand its sphere of influence and promote communism worldwide, leading to conflicting ideologies and competition for dominance. Additionally, territorial disputes, such as those in Eastern Europe and the division of Germany, further heightened tensions between the two superpowers. The development of nuclear weapons by both countries also contributed to the rivalry, as it created a precarious balance of power known as the "Cold War." Overall, the combination of ideological, territorial, and military factors fueled the tense relationship between the USA and the USSR after World War II.