Not necessarily. Being able to imagine the deliberate crashing of airliners by terrorists (like Tom Clancy in Debt of Honor) is not at all the same thing as being able to prevent it in a free country of 300 million people. Just like there's nothing to stop somebody from stealing a gasoline tanker truck and ramming it into an elementary school.
Life is not a comic book. You can't stop every bad guy in the world, especially fanatical ones. You cannot pursue every conceivable possibility. I don't blame the Bush administration for failing to prevent 9/11, nor do I blame the Clinton administration. There are things both could have done better, but it probably wouldn't have stopped what happened.
BTW, you are right about the folly of disarming people.
I believe you and I are in agreement. However, there are some here who need to stop believing that everyone in the Bush administration is above reproach and everyone raising legitimate concerns are out to destroy the country.
Actually in Debt of Honor it wasn't terrorists but the pilot who flew the plane into the Capital.
Even today we have no way to prevent something like this, in fact the reinforced doors that some laud would only insure that the passengers can not reach the pilot to stop him. (or her. Don't want to be called sexist.)
Arming the pilot? The pilot in the book killed his copilot IIRC with a knife. Having a gun at hand would only make it that much easier.
So, how do you propose to stop this kind of thing?