On January 4, a 28-year old Saudi national, Nabil Fadli, detonated a suicide vest in the ancient Byzantine Hippodrome next to Istanbul’s iconic Blue Mosque, killing 11 tourists. Turkish authorities have indicated that the bomber is an Islamic State member who crossed the Syrian border before making his way to Istanbul via the border city of Sanliurfa. During 2015, the Islamic State killed 141 Turkish civilians, police, and soldiers in four separate attacks organized and carried out by an IS cell based in Adiyaman, Turkey. This latest attack, the fifth IS-linked bombing in less than a year, differs markedly...