You might consult Krieg on that one, he has stated in the past, that if you are at war with an axis, you are not “neutral”. I know the US, if at war with Japan, can land in UK,Anzac and Dutch territories even if UK and Anzac have not declared war…The same should hold true of USSR. I had asked him what would happen if Japan attacked my US navy, and my carrier planes needed to land, they were able to land on UK/Anzac/Dutch holdings since I was at war and they were at war with Germany. Hope that helps…The true question is, will USSR still be neutral. I think we can look to examples with China, it has been said they could land in Burma, with the UK neutral and Japan would have to DOW UK in order to attack it. If that logic holds, Japan would have to DOW USSR to attack US units in their territories…Very confusing at times. Hope that helps.