My recommendation is to hit him hard in Normandy and see about landing only a couple infantry in Norway. Taking Norway loses him those IPCs plus the Scandinavian trade bonus, which will hurt his economy by at least a Panzer purchase per turn, and he can’t afford to split his attention so many ways. Just like he is trying with Russia, give him a death by a thousand little cuts. If you can convoy raid him (if you are playing with raids, that is), then you can knock him down even more. Of course, I may just be a bit overaggressive– I can’t see what all you can, but anything to stop the Scandinavian bonus is a good thing for beleaguered Russia.