It's sort of ridiculous that this conversation has degraded into debating who to blame for World War II and what was or was not excusable.
Listen, all those people are fucking dead!
Hirohito was the last surviving World War II leader; he died in 01989, 33 years ago, at which point the other leaders had all been dead for decades.
There's nobody left to blame or punish!
The youngest WWII soldiers were born around 01930, which is 91 years ago; there are very few of them left alive either.
I have the unpleasant feeling that some people are commenting on this thread because they support one or another of the belligerents in that bloody slaughter, as if it were a sportsball game, rather than because they are interested in what is true and what is false. How could you go about debugging a program if you had to argue with advocates of one subroutine or another, intentionally feeding you unreliable information so you'll blame a different subroutine for the bug? How could you go about analyzing a chemical reaction if you had to argue with people who were fans of one or another chemical compound, and tried to argue that their favorite compound would be produced from any reaction, whether or not the necessary elements were present? This is an excellent example of what I mean when I liken HN to the intellectual equivalent of the impoverished slums where I used to volunteer.
The relevant point to the factual question being discussed is that the European Resistance was, as you say, led by people who supported Stalin, and they had largely been put in charge of their various countries under the occupation of the United Nations. At the point that we're talking about, in 01945, the Molotov-Ribbentrop pact had been dead for four years, and Europe was full of the tales of noble sacrifices and terrible suffering the Russians had experienced in order to resist the Nazis. So Stalin could reasonably anticipate a lot more popular support and a lot less government resistance for setting up Communist governments in them, should he push his military advantage further, than Hitler ever had for setting up Nazi governments.