chicken and the egg thing: did this start during the 8th-11th centuries though? Muslims expanding into europe....and didnt the crusades-era create a nearly infinite animosity between the west and islam? i think there must be plenty of residual hatred, vengeance, etc. from all that. Then you have colonialism and partitioning and nation building adding to the resentment. There were no such countries as Jordan, Kuwait, Israel, etc. and the dividing up and installing Puppets like Mubarak etc. didn't help matters out either. Meddling in Iranian politics in the 50s (Mossadegh)....Culminating in Bush Sr, Clinton, and Bush Jr. certainly didnt help to combat any of that with their campaigns in Iraq, etc.

All these play significant parts in the roots of terrorism. I say its 50/50 like most things----both sides contributed quite equally.