Yeah so what’s going to happen with the Soviet’s and Japan can they fight does something need to happen?
Like calvin said, the two powers are best off ignoring each other for most of the game. If the fight goes badly for the Soviets, the Japanese would probably invade them. If the scales tip in favor of the Allies, the Soviets are more likely than not going to attack Japan.
As I said, the USSR can’t attack any Axis power for a few turns, which means if Japan foolishly attacks them, they’re going to regret it (unless they divert a huge chunk of their air force to assist, in which case that’s good–-less Japanese air power against the Chinese and Commonwealth forces.