The truth is those hijackers on 9/11 would not do crap wthout their cardboard cutting knives. Why allow those knives on the planes or any cutters. Without any weapons those people were just 4 people on the plane, easy to be overtaken by perhaps a dozen passengers.
It is still in my eyes the biggest flop of FBI and CIA and nothing more. You can kill millions but there will always be a dozen fanatics willing to commit terror acts.