U.S. Marines from Task Force Tarawa walk through the streets of Nasariyah, Iraq, on Saturday. After five days here, they're not quiet sure whether each Iraqi man they meet is friend or foe. Photo by Joe Raedle / Getty Images NASIRIYAH, IRAQ — Somehow, even under the cloud of death, life goes on in this town. A girl skips playfully in a yard. Herders tend to livestock. A police siren wails in the background. But the illusion of normalcy never lasts for very long. Sporadic gunfire is commonplace, and sends residents scrambling into their homes. Artillery blasts are less frequent,...