The success of GPS smart bombs in Afghanistan made air force planners realize that in Iraq there would be a lot more potential for ground controllers misidentifying targets and hitting the wrong target with great precision. There are a lot more military targets in Iraq than in Afghanistan, and more urban areas. So in mid-2002, the air force began updating their database of what was on the ground in Iraq. Satellites, UAVs and reconnaissance aircraft were used to update the existing database of potential targets. In the major cities, each building was given a unique number, and mission planners, or air and ground controllers, had to use that number to designate a specific building for a smart bomb. For a year before the war, Central Command set up special "urban bombing" exercises to give pilots experience in putting bombs down in crowded urban areas. The plan worked, as the only incidents of large civilian casualties on the ground occurred when the Iraqis faked American bomb attacks in crowded markets. Even journalists were able to see that the explosions were caused by explosives placed in vehicles, not bombs dropped from the air.