The seats, and landing gear photographed within the rubble in the Pentagon show it was no missile. The Truth movement tries to cover up and deny the debris photos.
If I was going to shoot a missile at the pentagon which looked like a plane I would plant the evidence before hand, duhh
Except it's far to small to be the thing eye witnesses reported seeing crash into the Pentagon. Also it did not make the explosion a missile would make.
There wasn't an explosive detonation at the Pentagon though, only a crash and fire ball. There was no debris before the crash, only the moment after the crash.