Originally Posted by Joe Obenberger

Only rarely and in sharply limited few circumstances does the constitution afford rights to non-US-Nationals outside the US. That general principal is why Guantanamo Bay was chosen for internment. But US courts became cynical about such a pat answer.

Protection of US territory and banning immigration from places and persons associated with seriosly elevated risk of danger does not appeal only to the uneducated. It is probably most prudent under present circumstances to halt the immigation of persons wha can't affirmatively establish that they amount to a nondanger, requiring visas for all travelers. But that's not really practical because nations will retaliate and require the same of US visitors. Perhaps the best that can be done is to temporarily ban visits from countries associated with high risk until a quite probing visa application and investigation protocol can be designed and tested.