I said that I suspected our military of perpetrating an Operation Northwoods type of false flag attack upon the American people for their own nefarious reasons. Perhaps the strongest argument against my suspicions is the fact that the Pentagon itself was one of the targets. Why would our military choose to strike their own headquarters, risking their own critical infrastructure and the lives of thousands of people vital to the military's operation? It sounds too implausible to be taken seriously. However, when we take a closer look at the facts, it turns out that they fit in rather well with the Operation Northwoods hypothesis.
The first relevant fact is where the Pentagon was hit. As Jim Hoffman informs us, the plane hit the one part of the Pentagon where renovation was just being completed to reinforce the building against a terrorist attack. As a consequence, instead of thousands of people being killed, there were only 123 fatalities.
The second relevant fact is that Hani Hanjour, the hijacker who flew Flight 77 into the Pentagon was unqualified to make such a technically complex flight maneuver.
The third relevant fact is that the technology existed that made it possible to hijack the hijackers. Aidan Monaghan, in his paper, "Plausibility of 9/11 Aircraft Attacks Generated by GPS-Guided Aircraft Autopilot Systems", explains how this could have been done.
So it is possible that our military "hijacked" Flight 77 and flew it into the only part of the Pentagon that was relatively empty and just lately reinforced to withstand such an attack.
So why would the Pentagon attack the Pentagon? Because our military knew that it was safe and that it would deflect suspicion away from our military.