In southern Turkey, hundreds of mourners gathered yesterday for funerals after a bomber killed at least 50 people at a wedding party for a member of a Kurdish political party. Turkish President Recep Tayyip Erdogan blamed ISIS for the attack. But some of the mourners threw bottles at police and chanted “Murderer Erdogan”—a reflection of the belief that the Turkish president’s support for rebels fighting the Syrian government has helped create the conditions that have allowed ISIS to thrive.