Wouldn't an expert Marine sniper been cheaper and more effective?
Yes, but some people get all jittery when you mention guns! Probably because it would actually prove to be an effective deterrent.
"Wouldn't an expert Marine sniper been cheaper and more effective?"
IIRC a few years ago some Marines were deployed on the border. Some fourteen year old US citizen got shot dead by said Marines while he was tending sheep and plinking with a .22. The border must be sealed that is for certain. I personally favor a wall one kilometer inside the border with a dead zone extending to the actual border.