War with Canada, though? Canada. I've genuinely never heard me or any other American on any political side have one negative thing to say about Canada, and we generally view them as our little brother no matter how frustrated and superior actual Canadians get about it.

The brits would be invading America's hat, it would be a war over the rule of the monarchy, and both sides being NATO members means NATO is not really a concern.

I don't think that would ever be a thing, but if it were a thing, I really wouldn't choose to be at war with anyone on US borders. Not even saber rattling. We're very paranoid, if that's changed at all it's gotten worse, and physically touching our borders will almost certainly draw aggro.

Plus, let's be honest, Canadians aren't brown enough to be ignored. We'd sell out Mexico faster than Canada simply because the cartels are too much trouble.