Number 1: These things are under development in the U.S. and I don't think they are drifting around in the black market. Also, last one I saw that could shoot down a plane needed a 747 to haul it around, so I don't think any terrorists are sneaking around with one hidden in their shorts.

In a related note, a special on Discovery Channel on Saturday showed future laser weapons that could be hauled around on a big Chinook helicopter, with a range of over ten miles and pinpoint precision. Such weapons make antiterrorism actions almost magical. The animation demo showed this copter standing off at some distance from a terrorist-occupied house, and then cutting the phone lines and flattening the vehicle tires in the front yard with this laser. Before, only Superman could pull stuff like this.

I don't know how far from actual development such weapons are.