Answer:
The ideological conflict between the democratic West and Communist Soviet Union.
Step-by-step explanation:
The relations between the Soviet Union and the United States of America went into breakdown mode because of the ideological conflict both nations had. The ideological conflict was the major reason why the cold war era began and both countries became enemies of each other.
After the end of world war, II USA and the soviet union became the two superpowers in this world, Initially, both nations maintained friendly and helpful relations with each other, The reason being both the nations were fighting a common enemy during World War II was Nazi Germany. But after the end of the war, the responsibility to set up a democratic government in Europe was equally divided between both Nations.
The Western European countries were given to the US while the eastern european countries were given to the Soviet Union, both the superpowers, set up governments that were favorable to their ideology only, and this led to the ideological division of both nations.