Well, everyone's arrived at the party now!
Do you have any plans to advance into Siberia?
Actually I've placed the 1st Army on the Korean/Manchurian/Soviet border, but don't plan on moving them. If the Soviets annex Manchuria before the Puppets arrive to save them then that gives me the opportunity to annex it back and have contiguous Japanese territory from Korea to North China...if the Puppets arrive in time *and* save them, that works too
Mostly I don't plan on moving off the defensive line until one of those conditions has clearly developed, if the puppet forces get up there and hold the line it will also give me an idea about the relative value of the Soviet units...but if I see an excellent opportunity to cause some real manpower damage I plan on taking that.