Does Turkey really support ISIS and, if so, why did ISIS just attack it again? Expert Aaron Zelin explains

The Islamic State carried out an attack against a Roman Catholic Church in Istanbul on Jan. 28, killing one person. In its statement claiming responsibility for the attack the group referred to Turkey as "Wilayat al Turkiya" — or its "Turkish province" — sending a chilling message that it views the country among its prime targets. Any further such attacks would deal a big blow to Turkey's multi-billion dollar tourism industry in the midst of economic turbulence.