So the USSR not only was responsible for beating 80% of the Germans they took a big chunk out of the Japanese (especially their air-force) early on, greatly helping the USA before it even got into the war. Anyway I still think the Sakalin oil would prove more important to Japan than any territories it might lose in Manchuria (not to mention delaying PEarl Harbour and USA entry, perhaps then the selfish isolationist tactic of the USA would have dire consequences) which would have also stretched the Russian war machine even further. Personally I think since Russia lost its eastern Navy to the Japanese in the last war they would just sit and take it (the Sakalin incident) with mostly big words and border skirmishes and concentrate on the big threat, the Germans. But hey if the Russians try to fight in Manchuria then the second objective of helping the Germans in the West is accomplished too and those oil shortages would start hurting in a while. BTW, how big a percentage of the total oil of the USSR did Sakalin compose? Was the Caucasu much more important? Though perhaps with a collaborating effort the Japanese could take Sakalin and Germans could focus entirely on Caucasus and not taking out Moscow and knocking the door out to bring the house down sillyness. With so much oil starving the Russian war machine and people would be dealt a more important blow and Iraq would be right there for the taking too. I'm also sure Turkey could be convinced to join at this point seeing the obvious benefits and the balance of power in the region. I'm also assuming its short-sightedness in regards to USA economic might, just like the rest of the nations.