Poland also did the exact same thing as the USSR did when it allied with Nazi Germany to annex part of Czechoslovakia. I don't deny that Stalin was an opportunist but nonetheless, despite its failures it was the USSR which did the lion's share of warfare against the Nazis and ended the holocaust. As for not taking part against Japan, they did invade Manchuria and would have turned their attention on the rest of Japan had they not surrendered to the USA (indeed the USSR entering the war against them was the biggest reason why they surrendered).

[–] [email protected] 1 points 2 years ago

(indeed the USSR entering the war against them was the biggest reason why they surrendered).

No, it wasn't. This is straight-up Soviet propaganda.