The thing to remember about walls is that they not only wall others out, they also wall us in. Just ask the inhabitants of what was once "East Berlin."
Hey wall builders, be careful what you wish for.
The New York Crank
No, not the Army. That'll just result in even more war crimes and brutalities. Round them up, at gunpoint if need be, and "escort" them to reservations somewhere out in the hinterlands. Preferably Antarctica, or the moons of Neptune.