Not sure if this was already stated (haven't read through all the posts) but a recent show, maybe the passionate eye, interviewed many who said the US defense wasn't designed to fight an enemy coming from within the US. All air defenses etc point out, not in. Air traffic controllers had difficulty tracking them, so even with early notice much if it may have been futile to stop. I suspect there have been a number of military upgrades since then.
Edit: I can see Johnny U making the same point.
Reminds me of an old karate instructor I once had. He said something like, "even with all this fighting training there is still no defense for someone sneaking up behind you and hitting you over the head with a garbage can."
Edit: I can see Johnny U making the same point.
Reminds me of an old karate instructor I once had. He said something like, "even with all this fighting training there is still no defense for someone sneaking up behind you and hitting you over the head with a garbage can."