Or for that matter (to be non-partisan) [link|http://www.dailypast.com/middle-east/us-marines-beirut.shtml|Beirut, Lebanon] in 1983?

Kill a few Americans, show some gore on TV, and they turn tail and run.

But, apparently bin Laden thinking that attacking the US at home as being worthwhile was a stretch. Still, for $100K in expenses to cause hundreds of billions in damage was hard to resist.