I, for one, would stand there with a shotgun aimed at illegals' gut, telling them, "Turn your ass right around and go back!"
If you did that you would be in more trouble than you can possibly imagine. Illegals, smugglers, and the Mexican Military are protected species here on the border. That is odd to me because US Citizens, especially the Border Patrol and LE officers are the most endangered species here, yet our government does not choose to protect them.