This is an adjunct to the socialism topic that seems to have been hijacked by amateur historians with all sorts of views on WWII and it's aftermath. To lead off I present a (I think) Russian quotation, with reference to why and how the war was won.
"the British provided the time, the Americans provided the money and the Russians provided the people."
The question to ask is not who won the war or why, as we will all have a (partisan) reason for our answers, but to ask what were the reasons for the subsequent divisions amongst the allies and consequently the course of the cold war.
US foreign policy shifted in 5 years from no intervention to, what seemed from the UK, total control. Why the shift? Especially considering the recent end to a major world conflict.
I am not going to post an opinion in the opening post, just wanting to see what the other posters see in this, with specific interest in the US perspective.