Even if theoretically the terrorists could have hi-jacked 4 planes, and have been able to fly them to their selected targets, how did these 19 people get past the billion dollar air defence system of America? Where was NORAD the million dollar system that can pick out any planes flight number? And where was the fighter jets?
But this lack of defence can be explained without including the need of a conspiracy. It’s still not good for the American government, especially the secretary of defence.

