Why was the relationship between the US and the USSR strained?

The relationship between the US and the USSR was strained primarily due to ideological differences, with the US promoting capitalism and democracy while the USSR advocated for communism and a one-party state. Additionally, events such as the arms race, the Cuban Missile Crisis, and various proxy wars intensified tensions. Mutual distrust and competing global influences during the Cold War further exacerbated the situation, leading to a prolonged period of hostility and rivalry.