I have been thinking about this post from The Big Picture all day. I often write that I am not worried about the U.S. losing manufacturing or other low skill jobs because long-term there will be a shift to higher paying jobs. Well, part of that expected job growth is in scientific areas, particularly research and development. If we discourage foreign scientists and graduate students from living here due to security concerns, we may pay a hefty economic price in the long-term. That is, unless American students are willing to pick up the slack. Coming from an engineering background, I can tell you that a significant number of engineering students are not U.S. citizens, and I don't see that changing soon. Here is the excellent point Barry makes at the end of his post.
We are more than importers of oil and foreign made products; We are the world's largest consumers of intellectual firepower. Strategically, if the 9/11 attacks succeed even in the smallest way in stemming the tide of brainpower travelling to the U.S., they will have managed to cause far more economic damage — over the long term — than the physical destruction they wrought on that terrible day in NYC.
It is an extremely bad idea to put obstacles to the "brain supply chain" . . .