@wittmann:
I do not think it matters. Just because you DOW, doesn’t mean you have to invade.
Many Russians will DOW first, as they can then move into Western China with Mech units to help out.
If the Russian players moves all 18 INf into Amur and has not DOW you first, I think you have to do so and ATTACK!
The bigger reason for Russia to DOW Japan on Turn 1 is so if Japan DOW’s the Allies, Allied units can move into Russia in the East.