Why did the soviet union want to have a buffer of countries between it and western Europe?

The Soviet Union sought a buffer of countries between itself and Western Europe to enhance its security and protect against potential invasions, drawing lessons from historical conflicts, such as World War II. By establishing control over Eastern European nations, the USSR aimed to create a protective zone that could serve as a first line of defense. Additionally, this buffer allowed the Soviets to exert influence and promote communist ideology in the region, reinforcing their geopolitical power during the Cold War.