>You'd think so, but Russia and Japan had signed a neutrality pact in 1941 and I assume that it was conveniant for both countries to abide by it for the majority of the war. Most books I've read basically accuse the USSR of out-and-out land-grabbing.

Then that would explain it. I wonder how the Germans felt about that since, in theory, the Japanese could have possibly drawn enough resources away from the Russian western front to have allowed the Germans to have overcome the Russians instead of eventually getting whacked by them?