After a Syrian rebel group Hayat Tahrir al-Sham led a lightning advance to take over most of the country and topple a longtime dictator, one group suddenly found itself out in the cold: Kurdish-led militias in the country’s northeast. The Syrian Democratic Forces, or SDF, was backed by the United States in the fight against ISIS and is now jockeying for land with rebels backed by Turkey. But why is Turkey in Syria? And what does it want? The World’s Durrie Bouscaren takes a look.