CEP Strategic Advisor Liam Duffy writes: "The more urgent concern, however, should be on Europe, and how the jihadist movement reconstitutes itself inside the continents borders after the Islamic State. The principal concern for security services has been the threat posed by Isis returnees, and with good reason. There is nothing new about Europeans travelling to jihadist conflict zones, but more travelled to Syria and Iraq for jihad than every previous jihadist insurgency combined. Not all made it home, but many did or will in future."