What Causes Terrorism?

sums up Robert Pape's view:

In contrast to the popular assertions that terrorists "hate freedom" or want to build a 21st century Caliphate, Pape documents the true driver of suicide attacks: to compel a democracy to remove combat forces from territory the terrorists prize and/or want to liberate. It is not primarily a function of Muslim extremism, even if Muslim terrorists have embraced the tactic.