The problem is that each side feels the same way. Each remembers some past injustice and each feels forced to take retaliatory action.
Terrorism is based on a foundation of defense. The terrorist leaders are telling their minions "look at what XXX did to us back in YYY! In order to preserve ZZZ, we must take action against XXX"
Whether this foundation is accurate is totally dependent on your perception. If you read the writings of UBL you will see references to past "injustices" committed by the US and other occidental countries. He uses his perception of past injustices to justify the need to take up arms against the "enemy".
Our perception is that his perception is not accurate.
Naturally we feel that our perception is right and we have amassed a whole bunch of facts that support our perception.
The funny thing is that UBL has done the same thing.
In my dealings in CT, I have never read any reports of any terrorist leader saying to his minions "here is country A. Country A has never done anything wrong or attacked us. I want some of you to sacrifice your life and attack them". Not the way to motivate troops.
It is always easier to motivate troops by framing the conflict in defensive terms
We (US and other occidental countries) cite past injustices (911 only being one) as justification for our being forced to take up arms against our enemies.
With each side truly feeling that they are responding defensively, there is little chance of ending the conflict peacefully nor of ending it diplomatically.
We can always take comfort in believing that we are right and they are wrong. What happens when they feel the same about us?
This is the tragic aspect of the so called GWOT. And one of the many many reasons it can't be "fought" like a traditional war. Killing them and bombing cities will not make them back down but will further motivate them. Our strategic planners are still fighting the last war it seems.