That doesn't justify letting bin Laden and Saddam Hussein's men into this country and giving them total access to everything to carry out their plans.
Terrorists don't need to visit the US to carry out an attack on American assets or citizens. Witness the Nairobi embassy, or the Cole. If you're serious about this idea of deporting all foreigners as a security measure, you'd also have to ban overseas travel by Americans. And what all this would do to American exports doesn't bear thinking about. How long do you think the boss of Dubai Chevrolet would keep buying cars, if he wasn't able to visit his supplier? Think it through, for crying out loud.......