US-backed Syrian fighters broke into the western part of the Islamic State terror group's stronghold Raqa yesterday. AFP reports quoting Syrian Observatory for Human Rights monitoring group that this is opening up a second front inside the northern Syrian city.<br/>The Syrian Democratic Forces alliance of Kurdish and Arab fighters has spent months tightening the grip on IS-held Raqa. The alliance forces entered the city of Raqa for the first time earlier this week from the east, backed by US-led coalition air strikes.<br/>Raqa, held by IS since 2014, emerged as a key hub for the jihadists' operations in Syria, neighbouring Iraq, and beyond. The Forces struggled to advance from the city's north as it was well fortified. The western and eastern entrances to the city were much less fortified and the coalition forces could pierce the city. The coalition strikes on the city on Saturday killed at least 13 civilians.