Since the start of 2015, jihadists have killed over 300 people and injured thousands more in a string of gruesome attacks in European cities. The assailants have driven trucks and vans into crowds, detonated suicide bombs, carried out mass shootings, and used knives and axes to attack, even behead, their victims. By and large, the attackers have been locals, but they have often received ideological support and practical instructions from members of the Islamic State (also known as ISIS).
In his new book, the French political scientist Gilles Kepel argues that among European countries, France has experienced the worst of this new wave of terrorism. Although the phenomenon of Islamist extremism “is not exclusively French,” he writes, “the French case is stronger and deeper” than the cases of other countries. Some 6,000 people, around 1,800 of them from France, have traveled from western Europe to join ISIS in Iraq or Syria or in one