recapture of mosul. cnn's international correspondent nick paton walsh live on the front lines near mosul. hi, nick. >> today, increasing details about one of the first u.s. casualties in this most yule assault. a soldier killed by an ied, a mine to you and me. we're not quite clear exactly where it was. we know it was in northern iraq. and may have been potentially involved in this assault against mosul. we've seen ourselves u.s. troops so close to the very front line, often in the first convoy of peshmerga armor that go in against isis. we saw repeated in the first clashes at dawn yesterday. day four and perhaps the biggest push yet. from the north into the plains around mosul. trying to dislodge the determined and deranged remnants of isis. for the peshmerga backed with staggering air power. the now common sight of american special forces. the pentagon says they're