And there's already a base they can use for "defense", it was really about defense. The difference is that if Russians come down that way now, the Brits and Scandinavian navies are there and keeping the Russians away from the US east coast too. If they take over Greenland, they'll be on their own and pretty fucked as EU has about 3 times as large navy as the US.
Conveniently forgetting that American actions are the reason Russia and China are hostile in the first place.