I suspect our proximity to the border would make it easier for terrorist.
Trouble is that our neighbors to the south don’t speak Arabic or tolerate their ilk. Unless he’s able to keep his mouth shut and fly way below the hispanic radar, a muslim terrorist is going to stick out like a sore thumb in Mexico.
Canada? Now that’s a different matter. It would be easy for the nefarious to assimilate in that country and then pass over the border.
bttt