The heavily armed fighters peered out of a broken second-story window at their outpost in a crumbling house on the western edge of this shell-shocked city, where Islamic State is fighting a furious battle to hold on to the capital of its self-declared caliphate.
They ducked to avoid snipers camped in nearby high-rise apartments. Armed drones hovered nearby. Just before 2 p.m. came the crack of sniper fire.
“That’s our guy,” Kevin Howard, 28, said as he rose and prepared to return fire.
Howard is not one of the hundreds of U.S. troops deployed in Syria. The U.S. Marine Corps veteran from San Francisco came here as a volunteer, part of a...