I find a little changing in the second Edition:
Page 39 Pacific Rulebook 2ed:
“If the Soviet Union attacks Korea or any Japan-controlled territory bordering these Mongolian territories while Mongolia is still a strict neutral, Mongolia will remain neutral and not ally itself with the Soviet Union.”
So attacking Korea with Soviet Union breaks in second Edition now the Soviet-Japanese Non-agression-Pact. Thats a difference to the first Edition. Its a decision from the developer to strength the Axis (here Japan).
Any comments?! New tactics now? Lower risk for Japan, that the russians attack Manchuria or Korea?