2) Why are they stupid? We have about a million visitors per year from the Middle East. Another 10 million from Asia and 500,000 from Africa, and about (edit) 80 million foreign visitors per year total. Unless we've identified a person as a threat they can travel here easily enough because we're a free country that is lenient on travel to and from here for all kinds of good reasons. And the ALERT!! said this twitter traffic was coming from around the world, and so the sympathizers could be any of those 80 million per year flying here.
I would expect that any serious terrorist threat to the U.S. would be well financed and well planned, and I expect that they can find individuals not on the U.S. radar easily enough.
Last edited by JasperL; 09-11-14 at 12:09 PM.