Rebels, Christian militiamen, local fighters: a cluster of Syrian Arabs united by their hatred for the Islamic State group have cast their lot with Kurdish forces to defeat the jihadists. Formed in October 2015, the US-backed Syrian Democratic Forces (SDF) have dealt blows to IS across swathes of territory in the north of the war-torn country. The 25,000-strong force is dominated by the powerful Kurdish People's Protection Units (YPG) but the Arab contingent has been steadily growing to around 5,000 fighters.
