<sod >The US-backed campaign to capture Isisâ de facto capital of Raqqa in Syria has officially begun, the Syrian Democratic Forces (SDF) has announced.< eod>< sod > The US-backed campaign to capture Isisâ de facto capital of Raqqa in Syria has officially started, the Syrian Democratic Forces (SDF) has announced, marking the beginning of the end of the so-called caliphate.< eod>