Originally Posted by
SPN Lifer
I am not trying to be argumentative, but whose fault was it, or what was the proximate cause, of the 9/11 hijackers being able to smuggle their blade cutters and whatever else they used for their plot?
There was no "smuggling" involved. The blades were permitted by regulation to be allowed to be taken onboard, they were not prohibited. They could have been openly dropped into a tray that went though a scanner and nothing would have happened. Unfortunately it is common in media articles to incorrectly/falsely state that the items were "smuggled" aboard, thus perpetuating the lie.
Sure there are other aspects that can be legitimately considered as contributing causes, such as non-hardened cockpit doors, a policy to cooperate with hijackers, etc., but a failure of airport security screening was NOT one of them.