The Cold War was caused by those damnable glaciers. Thankfully, global warming is clear evidence of our victory! 
Seriously…
“Or maybe both sides were to blame fo their excessive paranoia.”
This is closer to the truth that what the majority of the posts here seem to indicate. To paint the Cold War (or almost any conflict, for that matter) as simply good vs. evil is the intellectual equivalent of Dick and Jane.
“See Americans good. See Soviets bad. Bad, Soviets, bad! See Soviets fall. Dance, Americans, dance! Good Americans.”
The Cold War is better viewed as a contest between two competing ideologies, neither side with a monopoly on virtue. Were actors on the Soviet side more brutal in practice? Certainly. Men like Stalin and Beria were not cute little puppies by any stretch of the imagination–they were murderous bastards who, in their own twisted and self-deceiving way, had convinced themselves that the good of the state (and their own personal skin) was more important than any individual. Or any million of individuals.
It is unlikely any of us will approve of heavy-handed Soviet methods. But this is not the entire issue at hand. We can not necessarily say that the Soviet Union was expansionist because of the nature of its system. Curtis LeMay (the infamous head of the US Strategic Air Command) was not alone in his desire to crush the communists with nuclear weapons while we held the ability to do so without risking a response in kind. Would we argue these decidedly expansionist notions were inherent to the American way of life? I think not. We had no need to resort to such drastic measures, and thankfully cooler heads prevailed.
Ironically, the main difference between the Soviet and American systems may have been a 140 year head-start. American subjugation of its native population in the years following democracy’s inception is eeriely similar to Soviet subjugation of its population, though of course the latter took on a different style–it was mechanized, organized inhumanity. Our brand of ideology had already completed its expansionist phase while that sort of “sword and civilization” philosophy wasn’t particularly frowned upon. By the time the Soviets got around to it, the barbarity of it was all too apparent to Western eyes. In the Communist mind, putting down the occasional democratic revolt in Prague in the 20th century was all for the greater good, not for evil–just as Americans of the 19th century would have viewed the destruction of the Apache… or just as the WW2 Allies would have viewed strategic bombing that had little regard for civilians.
If we argue that the Soviets of say, the 1950s, acted as agents of evil in Eastern Europe, it would be difficult to argue that America did not too do its share of evil, even if in the name of good, whether it be in Iran, Korea, Vietnam, or any number of lesser known interventions. As an American, it is all too easy to blame the Cold War on the obvious Soviet aggression because we want to be the good guys. To at least some degree we were good guys and the Soviets were brutal. But let’s not oversimplify, either.