What's Next for Turkey, the U.S. and the YPG After the Afrin Operation?

Turkey's decision to conduct a full-scale military incursion into Afrin, Syria --involving airstrikes and ground forces -- should not come as a surprise. For the past three years of the campaign to defeat ISIS, the United States has increasingly turned to Syria's Kurds and their most dominant political and fighting force, the People's Protection Unit (YPG). But the YPG is the sister organization of Turkey's Kurdistan Workers Party (PKK), which has fought the Turkish state for more than four decades and has capitalized on the civil war to establish its own, self-governed autonomous region in the northeast of Syria known as Rojava (Syrian Kurdistan)....