Those are the ones who have already forgotten...
We should always keep in mind that the first pre-emptive attack against global terrorists was not conducted by trained and well-armed military forces or well-intentioned politicians but by ordinary citizens doing extraordinary things.
Having come to realize the nature of the enemy and his intent, the passengers of Flight 93 chose to take the enemy out before he could accomplish his mission. Instead of rolling over and accepting the brutality of their captors the passengers visited brutality on the terroists' 'muscle men' rolling over them denying the enemy his victory.
There are most likely many unknown people living and working along Flight 93's flight path or in and around the US Capitol, the intended target, who owe their lives to the actions of these American heroes. Some of those people might also be the very same people who are today advocating that we simply roll-over and accept the brutality of our enemy in the Iraqi operation and demand that we not visit brutality back upon them.
Forunately some of us never will...