Suicide attacks in Paris, Brussels, Orlando, Istanbul.
And where to begin in Syria, Libya, Iraq, Somalia, Israel? Further back, attacks in the United States, Mumbai. Nearly commonplace in Afghanistan and Yemen.
Why? What are these young men and women thinking? Are their minds focused on a reward in a world beyond this one, or are the motives more earthly - human?
This week on War College, we speak with Roger Griffin, an expert on the motivation behind militant attacks. He offers explanations for actions that seem inexplicable.
The views expressed in this article are not those of Reuters News.