A superb analysis by Yuval Noah Harari, who states terrorists have almost no military strength so they create a spectacle anticipating their enemies reaction will give them victory - one day:http://www.theguardian.com/books/201...arari-sapiens?

He is the author of 'Sapiens, a history of humanity' due out next month, so only has expert reviews:http://www.amazon.com/Sapiens-A-Brie.../dp/0062316095

A taster:
...even sporadic acts of political violence that kill a few dozen people are seen as a deadly threat to the legitimacy and even survival of the state. A small coin in a big empty jar can make a lot of noise.

This is what makes the theatre of terrorism so successful. The state has created a huge space empty of political violence. This huge space acts as a sounding board, amplifying the impact of any armed attack, however small.