Christian Lowe, contributing writer

IT'S THE TOUGHEST kind of battle imaginable. A sniper around every corner. Ambushes on all sides. Booby traps and mines at every step. It's hard to tell friend from foe. Casualties are the rule, not the exception.

Welcome to urban combat.

As U.S. forces pick their way through the densely populated cities of Iraq in search of Baath-party holdouts, Fedayeen Saddam fighters, and remnants of the eviscerated Iraqi army, they will be fighting on one of the most feared battlegrounds--the city.

From Stalingrad to Seoul, Hue City to Sarajevo, Mogadishu to Groznyy, history is filled with the tragic tales of urban brawls. If they can avoid it, U.S. forces would certainly prefer not to confront an enemy in city streets. But oftentimes, enemy forces prefer to draw U.S. troops into the warrens of streets and alleys, using civilians as shields and local knowledge for cover. The enemy knows the United States won't demolish entire blocks, as the Russians did in Groznyy. And he thinks exacting a high toll can send the Yanks running with their tails between their legs, as happened in Mogadishu.

But the military has been training to confront the threat of urban combat for nearly a decade and has adopted a methodical, high-tech approach to avoid unneeded suffering and to stymie the dirty tricks a wily enemy can throw at them.

The power of overhead surveillance from orbiting aircraft and unmanned drones, such as the RQ-1A Predator and RQ-4A Global Hawk, have proven pivotal in taking away the local militia's inherent knowledge edge. Smaller, man-portable drones, such as the Marine Corps' Dragon Eye, can be sent on specific missions to see around street corners, surveil rooftops, or buzz caravans of vehicles suspected of transporting enemy forces. The local guerrillas may know the perfect spot to set up a sniper position, but before long, U.S. forces will know it too, without risking a potentially fatal reconnaissance mission.

The military has also paid a lot of attention to the lessons learned from other tough urban fights, including the Russian army's disastrous first war with Chechen rebels in the streets of Groznyy in 1994 and Israel's experiences in the Palestinian refugee camps. Planners have been taking a good hard look at what worked and what didn't and incorporated these lessons to their own urban operations tactics. The use of armor in a city has been a particularly dangerous tactic--a single enemy fighter armed with a rocket propelled grenade can trap an entire convoy of armored vehicles with one shot, a lesson learned the hard way in Groznyy. So instead of cruising through the narrow city streets of Baghdad with M1-A1 Abrams tanks and Bradley fighting vehicles, the armor sticks to more open terrain, surrounding swaths of the city to isolate the enemy and keep him from reinforcing or escaping.

And that's when the tough part begins. After precision air strikes have pounded enemy strongholds spotted by ground and air-based forward air controllers, it's time for the foot soldier to get out of his armored vehicle or Humvee and kick down some doors. This is where things can get bloody. Going door-to-door, clearing individual rooms can be costly. A suicidal enemy holdout can cut down a U.S. team as it slams its way into a room.