This was very important early in the Cold War. In fact, it did a great deal to start the conflict.
As World War II drew to a close, the Soviets perceived the West as a threat. Therefore, they wanted to have a buffer zone that they controlled in Eastern Europe. This would, they felt, protect them from invasion. The Western Allies perceived communism as a threat to their way of life. They saw the Soviet desire for a buffer zone as an expression of the communists’ desire to take over the world.
In this way, the perceptions and misperceptions by each side led them to distrust one another and the Cold War was under way.