>Getting boots on US soil would be even tougher.

Getting them there seems easy, its the keeping them there that seems like a logistical nightmare.

>You'd have to have a fleet of ships that would be detected as soon as they set sail, and then protect that fleet for the entire voyage, which would also be extremely difficult for any adversary.

Or make friends with one of your neighbors that the USA appears to be keen on pissing off constantly. I have never seen more negative sentiment about the USA from Canadians before, who now see the USA as a strategic threat instead of their mentally challenged neighbor.

And dont get me started on Mexico, they can probably be had for pennies.