In Syria, the Rebels Progress at Their Allies' Peril

Syrian rebels, with the help of the Turkish military, are slowly making their way across northern Aleppo province. As the rebels draw closer to the strategic city of al-Bab, their progress is wreaking havoc on the plans of the Syrian civil war's other participants. Kurdish and loyalist fighters -- as well as their U.S., Russian and Iranian backers -- will be forced to rethink their strategies as the risk of conflict with the advancing rebels rises....