In this July 22, 2017 file photo, Arab and Kurdish fighters with the U.S.-backed Syrian Democratic Forces (SDF), move to the front line to battle Islamic State group militants, in Raqqa, Syria.
In this July 22, 2017 file photo, Arab and Kurdish fighters with the U.S.-backed Syrian Democratic Forces (SDF), move to the front line to battle Islamic State group militants, in Raqqa, Syria. HUSSEIN MALLA ASSOCIATED PRESS
In this July 22, 2017 file photo, Arab and Kurdish fighters with the U.S.-backed Syrian Democratic Forces (SDF), move to the front line to battle Islamic State group militants, in Raqqa, Syria. HUSSEIN MALLA ASSOCIATED PRESS