True, Id would say that the primary factor effecting the Soviet Union declaring war was the threat from Germany once that was gone it was game on.Stalin was never a fan of "keeping" non-aggression pacts he just used them to gain time Germany beat him to the punch in 41 and of course had as much intention of following that pact as the Soviets did.
Sorry to be so aggressive towards CaptainMattJ. post I know this is a speculative topic but one does have to consider actual conditions and he seems to have little knowledge of Japanese-Soviet relations in 30-40's and their military capabilities as well.
I have read extensively on WWII and related history particular about the Soviet Union and Japan in my 30 or so years so sometimes my stuffed brain gets a little excited I guess.
Edit:heck yeah check out my new digs!! I hope it does not last just one post
