U.S.-backed force launches assault on Raqqa A U.S.-backed alliance of Kurdish and Arab fighters has launched an operation to capture Raqqa, de facto capital of Islamic State SYRIAN DEMOCRATIC FORCES (SDF): Alliance of around 50,000 Kurdish and ethnic Arab militia dominated by Kurdish Popular Protection Units (YPG) – key ally of U.S.-led coalition against IS in Syria SYRIA Raqqa Damascus SDF attacks Division 17 military base Andalus RAQQA Clocktower roundabout OLD CITY Mishlab district River Euphrates 800km 2,600ft 3,000-4,000 Islamic State fighters thought to be holed up in city UN estimates around 160,000 people still trapped in city Source: Syrian Observatory for Human Rights Picture: Google Earth © GRAPHIC NEWS