washington u.s. military say tuesday could confirm 90 percent syrian city raqqa retake islamic state militants even u.s.-backed force declare victory syrian democratic force sdf alliance kurdish arab militias say fight clear raqqa stadium mine remain militants formal declaration victory raqqa islamic state de facto capital syria soon make city clear mine possible islamic state sleeper cells say sdf spokesman talal selo fall raqqa islamic state stag euphoric parade string lightning victories 2014 potent symbol jihadist movement collapse fortunes colonel ryan dillon spokesman u.s.-led coalition fight islamic state say 100 fighters still remain raqqa expect sdf face resistance remnants militant group aware report isis defeat raqqa dillon say use acronym islamic state however clearance operations continue expect syrian democratic force partner hit pocket resistance final part city clear dillon say say past days 1,300 civilians assist safety sdf 350 islamic state fighters surrender raqqa even sdf make gain raqqa dillon say islamic state fighters still remain middle euphrates river valley islamic state lose much territory syria iraq year include prize possession mosul syria force back strip euphrates valley surround desert ninety percent raqqa retake islamic state u.s. military