US-backed forces breach wall in Syria IS stronghold Raqa

US-backed forces in Syria have entered the most heavily fortified area of Raqa, the de facto capital of the Islamic State group, in what a US official says is a "key milestone" in the war against the jihadist force.Success in Raqa and major advances by US-backed forces in Mosul, a second IS stronghold in Iraq, represent a powerful double blow to the violent extremist group.The SDF faced heavy resistance, as the IS fighters used the wall as a combat position and planted mines and improvised explo