IRBIL, Iraq — The U.S. military headquarters here is outfitted with maps showing a "forward line of troops" — a FLOT, in military-speak — that divides northern Iraq's Kurdish region from territory held by the Islamic State group. The line is precisely drawn, following the contours of specific roads and berms. A mere 40 miles west, the terrain is pocked with trenches, fighting positions, razor wire and armed checkpoints. It's like a scene from Europe during World War I, one American official says.