Turkey's President Recep Tayyip Erdogan addresses a rally marking the 563rd anniversary of the Ottoman conquest of Istanbul - formerly Constantinople - in Istanbul, Turkey, Sunday, May 29, 2016. Erdogan has criticized the United States, Russia and Iran for their presence in Syria and said their unwillingness to depose Syrian President Bashar Assad was contributing to Syrian peoples' massacre and pain.(AP Photo/Emrah Gurel)