Space Elevators *Can* Fall (Score 1)

The basic idea isn't to attack the base, but to attack the top. Without the counter-weight in geosynchronous orbit, the effect of the Earth's rotation and gravity would start dragging the ribbon downward. The process would probably be irreversable after an hour or two. At that point, you have several tens of thousands of miles of material entering the Earth's atmosphere and a fairly spectacular rate of speed. Even with very low weight, the kinetic energy would be devestating.

Now, obviously the top of these things is much harder to attack than the base, being in outer space, but there are plenty of launch vehicles powerful enough to send a fairly large bomb or small nuke on a one way trip to the top.

That being said, I still think space elevators are a better, safer, cleaner bet than rocket propulsion if we're serious about building our space infrastructure.