The problem of the hit on the Pentagon can be much simplified by asking
'what could possibly create the damage done?' The answer, oddly enough, is
nothing. Nothing known, that is. Or rather, nothing that is commonly known.
The entirety of 9/11 was a magic trick designed to fool the masses, not the
few very preceptive observers.

It was designed to create a groundswell of public emotion so that the Wars of Crude Oil
Acquisition could commence. The original entry hole into the Pentagon was small,
certainly not caused by a 757. Not only that, the entry hole then continued in
an absolutely straight line through five more reinforced exterior walls of the
Pentagon. Thus, it is totally useless to talk any further about the 757.

So what could it have been? The Frenchman, Thierry Massan, got it right nearly
immediately. It was a shaped charge, massive in size. How was it delivered? By a
cruise missile. It was the latest of Rumsfeld's deadly creations... So what
happened to the 757? Taken to some nearby military field, the passengers
murdered, DNA samples taken from each of them latter to be salted in the
Pentagon, there to be "discovered"...

Let there be no mistake, the gents who planned and executed 9/11 were not amateurs,
 nor were they at all squeamish about bloodshed and killing...   Henri the Celt.