Final assault starts on Syria's Raqqa as some Islamic State fighters quit

By John Davison and Ellen FrancisAIN ISSA, Syria/BEIRUT (Reuters) - U.S.-backed militias launched their "final" assault on Syria's Raqqa on Sunday after letting a convoy of Islamic State fighters and their families quit the city, leaving only a hardcore of jihadists to mount a last stand."The battle will continue until the whole city is clean," said a statement by the Syrian Democratic Forces (SDF), a U.S.-backed alliance of Kurdish and Arab militias.SDF spokesman Talal Selo told Reuters that "n