Just perusing the thread...
In case you haven't noticed, we're about the only real military superpower around with army, navy, and air force capabilities. Throw in the biggest & baddest toys, and we're pretty much kicking a wherever we go - as long as it is against a real army.
Problem is, that we're never going to be up against a real army, because we would just take them out like iraq retreating from kuwait in desert storm. Terrorists are now the new armies, and we're not yet great at dealing with them. We have a military built for conquest, but not for dealing with the police state aftermath which comes with regime building.
Get one thing straight - these people want to kill you because you threaten their way of life and ideology. They know that they have lost, so there is a desperate attempt to stave off the inevitable through escalating terrorist attacks. They will become bolder and more spectacular as their cause wanes and their failure is more apparent. You cannot contain fanaticism. You can only eliminate the fanatic. In some ways, this is actually a good outcome for all parties - they assuredly go to heaven, and you don't have to worry about them any more.
If you leave them alone, they will organize so that they can kill you. If you try diplomacy, they will lie to you until they can kill you. If you threaten them, they will run away until you drop their guard and they can kill you. If you mollify them, they will take your gifts and use them against you so they can kill you better. In short, all they want to do is kill you. How can you fight such an enemy? You must eliminate them. Simple as that.
The why, how, were and who did what is poppycock. It doesn't matter to them - they just want to kill you.