[quote=So Boerd]
You way overestimate China and Japan. The Russian Far East is the finest territory for guerilla operations in the whole world. Invading and defeating Russia from the east is impossible.
[/quote]

Basically this. I don't think that China or Japan can do anything else aside from having taken Vladivostok. I mean, are they going to force march through Siberia? They'd basically kill their soldiers so they can say they have control of basically nothing.