In September 2001, Europeans might have felt comfortable thinking that Al-Qaeda was only a scourge to the United States; some indulged in the unkind speculation that the United States had only itself to blame for 9/11. That innocence is now gone in the wake of attacks in Madrid and London. Since then Europe has oscillated through a range of stances in relation to Islamist terrorism, varying from country to country and across the political spectrum...