Russia cannot even take Ukraine, Europe if the sent their military in would stop them cold and push them back, Poland on its own would probably do that.
China, we will see there as lots of military around them not as technological but plenty of manpower and terrain to hit them from.
USA is the current wildcard as Trump seems to think he can do anything, midterms are key as they control congress now which is meant to be a balance to him, if Democrats take control he is in for a world of pain