@Baron:
Another 4th point to make things bitter for Japan:
Geographic limitations to Asia (only east of Urals) for Japanese,
but close Trans-Siberians Railroad (for Soviet) toward east if Novosiburk is captured  (Timguska on G40),
+6 NAP bonus for both,
activation of Pro-Soviet Mongolians if Japan breaks NAP. (GHG idea)
I love the 6 IPC NAP idea in your former post. Unfortunately, it is moving far away from Der Kunstlers opening post, so maybe you should start a new thread based on that idea. But if K. dont mind, we can continue here.
I dont utterly love the geographical limitation idea, since it is not in the spirit of A&A, and it is not how the real world function either. If a Russian person can go to Timgusta, then so can a Japanese person, unless there is a wizard with magic power living there who autokill all Japanese persons that enter that place. But then it would not be A&A anymore.
A more rational suggestion would be to make Yakut SSR into a semi impassable territory, since the terrain at that place, the Lake Baikal surrounded by high mountains, is very hard to move through. It would be kind of like the Pripjat Marshes. The terrain in Yakut is in military term, an easy defended bottleneck with natural flank protection. I would say, you can only non combat move into Yakut, and that is probably correct in real life too. Or, you can only combat move into Yakut if it is defenseless and vacated, like total empty.
I also like the activation of Pro Sovjet Mongolians if Japan breaks the NAP.
If we also say that the border between China and Russia is impassable, as it is in real life too because of the Hindu Kush mountain range, which basically is the Himalayas continuing north, dividing China and Europe in a natural way. Then, the only way for Japan to Tank Crush into Moscow, is to go through Mongolia. I love this. This is exactly the problems Japan would face in the real war, if they wanted to go to Moscow. It was not impossible, but very difficult, costly and time consuming. Now Japan will stay out off Moscow, but not because of some non aggression treaty rule, that politicians and national leaders from any places would break at first opportunity anyway, but because it is too difficult in practice. It is doable, but only if you commit everything.