If our troops have to go into Iraqi cities, things could prove very difficult indeed. Our best hope is that either the government collapses quickly with Saddam fleeing, dying, or being captured, or that we can encircle the cities and wait them out. Read about what happened in places like Stalingrad, Leningrad, and Berlin and you'll see that urban warfare is especially nasty. Look at what it took to take out those 6 terrorists in the story and multiply that by a few thousand times as you have to go door to door, sewer to sewer, and rubble pile to rubble pile clearing out pockets of resistance.