The tribes in eastern Syria have been driven in different directions by the Assad regime, outside actors, and their own self-interest, leaving the coalition with a complex web to untangle before it can fully uproot IS.This week, Kurdish and Arab fighters from the Syrian Democratic Forces pushed west into Islamic State-controlled territory in a bid to seize the town of Manbij. Only days earlier, however, the beginnings of a longer southward campaign -- to retake the IS "capital" of Raqqa -- were set in motion when the SDF began attacking IS positions in Balikh Valley, about fifty kilometers north of the city.
The latter offensive is far from a blitzkrieg that will bring the SDF to the outskirts of Raqqa promptly; for one thing, the Kurds may be distracted by their oft-stated goal of continuing westward toward Afrin in order to link up their two border enclaves (see PolicyWatch 2542, "The Die Is Cast: The Kurds Cross the Euphrates"). Yet the SDF's main military patron, the United States, has another reason to be cautious about the Raqqa timeline -- before the coalition even thinks about launching a final push on the city, it must rally the Arab tribes in the area, some of whom have pledged allegiance to IS.
Any such effort will require a thorough understanding of the evolving role that tribes have played there, first under the Assad regime and now under IS rule.