The first obvious question is—which people are most vulnerable? The obvious answer: primarily young Muslim men in urban environments and some young women. But, this is not about fanaticism or brainwashing—a term invented by the US in the 1950s. It is about the combination of a series of factors which leads an individual to make a series of choices which appear to them, at least at the time, as entirely rational. It’s not about being mad or bad. Some recruits are rich, some not. Many are educated, some are illiterate. The background differs around the world. In the west, particularly in France and Belgium, recent ISIS attackers and sympathisers have been from relatively poor backgrounds, though far from destitute. Those in the US have tended to be better off. This reflects the general circumstances of the Muslim community in each environment.