The US and the USSR were allies during WW2 and as such we didn't really have a right to claim control of all of Europe. The US did everything it could short of war with the Stalinist government to get better treatment of Eastern Europe. It was a constant pissing match for either democracy or communism. Eventually we prevailed but, yes, it took a long time without waging war.
If I may bring up another WW2 example where the US did a great thing, Japan who attacked us directly and was conquered by us had to submit to our post-war dictates about how the country was to be run. Those in power in Japan were terrified of what we would impose but Douglas MacArthur with a committee of military officials with law degrees drafted a constitution and set up a system that is still in place and working well. The Japanese expected to be punished ruthlessly after the war but instead MacArthur is considered a hero in Japan...how often does that happen?
The big difference between that and the US interventions throughout the world today is that our wars are now run by politicians trying to get votes and since we are just trying to keep or put a friendly government in power we don't have any real say in how the government eventually forms. What we end up with is a fractured, chaotic and weak government that isn't particularly popular with the people or neighboring countries.
The frustrating part is that if we do something...we look like a bully...if we don't then we are still vilified for standing by and letting bad things happen. Personally...I think we should just pull back and be isolationist. Let the rest of the world sort out their problems on their own.