Why did the USSR try to create communist governments in eastern europd?

Answer 1

Imagine you're fighting the war as an ally of a nation which hates your political system. You have a strong suspicion that once you have finished off the Germans, your allies will turn on you. The further you can keep them from your borders, the less chance they will have of winning such a war. So you take over all the little countries between yourself and them; these are called buffer states. Now it's not possible for American troops to set up bases on the borders of the USSR. It worked, too. Without that strategy, WW3 would have happened.