IS have and its predecessors have been on the go since the 1930s - what's different now is the splinter groups that have caused the terror - either homegrown or European based - are much harder to track and neutralise.
Some of the action credited to IS has been little more than in the name of IS - with little real input from them themselves, It's this random terrorism - the guns on the beaches terrorism that we saw in Tunisia - that worries me. It's also clear that those who have been involved are not disillusioned working-class muslims but those from well-educated middle-class backgrounds. What makes someone who has everything going for them strap a bomb to themselves or go on a suicide shooting mission? That is the real frightening thing.