At 11 a.m. in the Iraqi capital, the popping of automatic-weapons fire broke out from one end of a Tigris River bridge to another. Pedestrians jaded by gunfire walked for cover. It was Baghdad’s equivalent of a car horn — guards shooting into the air to clear the way for some dignitary. Across the Tigris, gray smoke billowed over the city from a bomb. Under the bridge, ski-masked Shiite Muslim commandos cruised through checkpoints in pickups mounted with machine guns.Full Story