U.S.-backed forces push back Islamic State in Raqqa campaign - officials

By John DavisonBEIRUT (Reuters) - U.S.-backed forces fighting Islamic State in Syria advanced to within 2 km (1 mile) of a key stronghold near the jihadist group's de facto capital of Raqqa on Tuesday, and a counter-attack by the militants was repulsed, officials said.The multi-phased campaign by the Syria Democratic Forces (SDF), backed by air strikes and military advisers from a U.S.-led coalition, ultimately aims to oust Islamic State from Raqqa.Officials have given different estimates for ho