I should think that invasion from either side would be far fetched, since either side can easily maintain local air superiority (all they have to do is zoom in, waste the tankers, and zoom out, all the other planes won't have the range to cross the Atlantic, except for heavy bombers without escort).

the US does have the stealth trump card, which can theoretically fly in and blow away enemy airfields before they know what's happening. (can anyone give me reliable numbers on the number of B-2s we have?) Each B-2 can carry 16 JDAMs or JSOWs, which is bad news for anyone.