The conspiracy crowd point to the fact there was nothing left of the airliner that hit the Pentagon on 911, and insist that it was really a missile. This video shows a test of construction techniques used in nuclear plants, which are designed to survive a hit by a large aircraft. In this case, a F-4 fighter was used, The F-4, like all fighters, is more sturdily built than airliners. Yet this F-4 disintegrates when it hits the concrete. The same thing happened to the airliner that hit the Pentagon, which has been rebuilt with stronger materials.