It is a popular misconception, perpetuated by repetition, that Sept. 11 was a direct result of the failure of airport security.
Unless there is something we have not been told, none of the weapons used were prohibited items either by US or European standards. (They are now). It is just that the terrorists chose to make the US their target. Most were living or had lived for considerable periods in Hamburg. Had they decided instead to pick a German, UK or any other airline (LY excepted) and targets in Europe, can anyone state categorically that the outcome would not have been the same ?
In fact, the US had the mechanisms to be more secure than Europe - the CAPPS and the FBI watch list. That these apparently failed miserably is an indictment of the overall intelligence system not airport security. Which makes the current concentration on this particular aspect all the more questionable. IMO of course.