Jopa you're not answering the question.
Indeed I am. I was asked by Yakman, that how so the Allied pre-WWII politics enabled the USSR to become a superpower? My answer to this question is, that leaving Poland alone and not respecting the agreement signed, the Allies gave the others - for Germany and the Soviet Union - a free hand opportunity in this matter. The Allies again closed their eyes while the Soviet Union practiced expansionism considering Finland and the Baltic States.
During the end-game of the WWII, the Allies had two opportunities - in Tehran and in Yalta - to influence the creation of the post-war Europe. Again Roosevelt and Churchill did care a very little about the Eastern Europe, they allowed Stalin to spread communism and the creation of the satellite states for the USSR. After the WWII, Stalin was at the top of the tree, mastering Eastern Europe and partly Scandinavia - Finlandization is used to describe a process by which a powerful country obliges the minor to adapt foreign policy rules.