Erdoğan and Gülen: Allies to Enemies

Today, authoritarian Turkish President Recep Tayyip Erdoğan treats cleric Fethullah Gülen and his followers as political enemies.  But why were Erdoğan and Gülen once allies?  Dr. Aslı Peker, Clinical Associate Professor in the Program in International Relations at New York University, explains the complex history behind one of the most significant political developments in contemporary Turkish politics.