We need a double wall. The interstitial space should be landmined to high hell, and have automatic targeting 50 al machine guns to take out any living critter who illegally enters the space.
A moat with alligators would be nice also!!!!!
Wall is needed but, more than that—it must be manned or Mexico will just use a big ladder and get over it. I believe it should be a wall and a chain of forts. It should be manned by a new Unit of the Military—The Border Guard. Like the coast guard but on land. Should have armored cars, planes (Warthogs?) helocopters, cannons, and gunboats. All fix to battle the Cartels. Other nations have such armed forces—we should as well.