We may yet see a scheme like this:
A long time ago, one of Reason magazine’s writers suggested that Israel could secure its borders against the more common sort of invaders and terrorists by making them radioactive, such that anyone who attempts an unauthorized entry would be fried as he did so. At the time there were practical problems that made such a project dubious of completion, but the fundamental idea — make the border automatically hostile to life — remains attractive.
Today it could be done rather easily, and at a modest cost compared to the complete militarization of the border. Indeed, it could be incorporated into President Trump’s proposed wall. Don’t bother climbing over or tunneling under it; either way you’ll get a lethal dose of neutrons. Anyone who did manage to cross would be easy to detect by his, ah, glowing personality.
Of course, if you’re a traditionalist, you may prefer the Hungarian approach.