It seems like most agree that an invasion and occupation of the United States by any power (european or otherwise) is nigh impossible post-1900. But what about the opposite?
That's it, could a very expansionist and agressive north american state (be it the United States or some ahistorical alternative), contained within the western hemisphere and with no clear allies anywhere else, be able to invade and/or occupy a foreign power based across the Atlantic?
The 'no clear allies' anywhere else part is the kicker. The normal way to do this would be to have some client states and/or allies that you use as bases. Divide et impera.