Massive empires always collapse? Which is why I'm willing to bet the United States have a few decades left in them before they kick the bucket and the world is free.
Many leaders had pacts with Hitler before he turned against them, the allies did, Yugoslavia did, etc... The Soviet Union was just trying to protect its intersts, that is, until Hitler decided that Slavs were untermenschen (I'll need to brush up on my German but I think that's the term) and proceded to try and turn the Slavic world into Germany's breadbasket.
And for the record, for people here crying about the allies' crimes, and the bombing of Dresden (which I'm sorry, but I can't feel the slightest sadness, even though beauties were destroyed). Hitler's army flattened: Warsaw, Belgrade, Rotterdam. Bombed mercilessly: Moscow, St. Petersburg, parts of Prague, Budapest.
Then Hitler decided that one German life was worth 10 Serbian lives. So when 4 German soldiers were killed by hooligans while patrolling Serbian towns, Hitler ordered his men to kill 40 boys from a local high school where my mother grew up. She said even through her childhood, the mothers of the murdered kids would cry and lament.. Can you imagine, purposely picking high school boys and putting them out on a shooting range?
I say thank you Russia for having helped destroy Germany, and sorry Europe for having embraced Germany once again. I don't believe they can be trusted for... too long.