Charging out a hatch in the rear of a Bradley Fighting Vehicle, two soldiers approach the edge of a zigzag desert trench strung with concertina wire, and toss in a live hand grenade to clear an entryway. Then they jump into the elbow-deep trench and fire M-16 rounds in each direction. With this foothold established, the rest of their eight-man team follows, advancing slowly down the length of the trench before a second Bradley approaches and drops off its load of infantry.

These soldiers and others from the U.S. Army 3rd Infantry Division spent the past week camped in the wind-swept Kuwaiti desert, training for situations that U.S. war planners hope the troops never have to face. For five days and nights, they practiced warfare on a makeshift urban combat course, followed by two days of training to clear trenches and bunkers at a remote range just south of the Iraqi border.

"These are high-risk operations in battle," said Lt. Col. Stephen Twitty, commander of the division's 3rd Battalion. "But even in this day and age, with the technology we have, sometimes you have to put boots on the ground and engage at close range."

Both exercises were designed to prepare the soldiers, including several teenage privates fresh from boot camp, for operations that have historically produced high casualty rates but that could come into play if a war against Iraq proves more complicated than some military analysts have foreseen. With the U.S. public grown used to high-tech military operations with low casualties, U.S. war planners cite close-range combat as their worst nightmare, but one they must prepare for.

"Going through all this gives me more confidence about what might be coming up," said Pfc. Benjamin Carter of Tacoma, Wash., who turned 18 less than a month before arriving in Kuwait in late October. "I guess that's the point."

Urban warfare is something that many of the soldiers who took part in this week's training said they would prefer to avoid. "There's nothing easier to defend than a city," said Lt. Matthew McKenna, 23, of Gaylord, Mich. "And nothing scarier to have to attack. We'd all have become casualties at one point or another during the training if it were real. But the more we've trained, the better we've become."

The U.S. military has stepped up preparations for urban combat in recent years, seeking to lower casualty rates that ran above 50 percent in battles such as that for the city of Hue during the Vietnam War. Observing the training this week was Sgt. Maj. Robert Gallagher, one of the soldiers who in 1993 was stranded in Mogadishu, the capital of Somalia, during an urban warfare disaster for U.S. forces; 18 U.S. servicemen were killed when an operation to capture a warlord was met by a Somali militia ambush.

About 150 soldiers from the 3rd Battalion, 15th Infantry Regiment's Bravo Company participated in practice runs on the urban training course, culminating in a live-fire assault on a full-scale replica of a bombed-out city block. Supported by mortar fire and a couple of M-1A1 Abrams tanks, the soldiers moved building to building, knocking down doors and firing M-16 automatic rifles to clear each room.

The terrain on which the soldiers were training is a duneless ocean of crusty sand with no vegetation. Skies were free of clouds, but hazy, and a constant stiff breeze kept the exposed landscape cold, even at midday. At night, the desert was lit by the glow of an almost full moon.

Gallagher said that in the event of war with Iraq, soldiers should be prepared to fight in the streets of Baghdad. The Iraqi president, Saddam Hussein, said in a speech broadcast today that invading American soldiers would face "suicide" at the gates of the Iraqi capital.

"This is the dangerous stuff," said Capt. Michael Cutler, a medical officer who taught triage and battlefield first aid between exercises. The soldiers, he said, had never before received that type of training. "There are important differences from regular first aid -- one guy has to know how to do it all, without help sometimes."

Toward the end of the week, the company moved a few miles down the dusty moonscape to Range 7, for trench- and bunker-clearing, a task Twitty called "fundamental" to the infantry mission. During the 1980-88 Iran-Iraq war and the Persian Gulf War of 1991, Iraqi soldiers dug hundreds of miles of trenches. This led to a bloody stalemate with Iran, but in the Gulf War, advancing U.S. forces found most of the trenches empty, as the Iraqis had either surrendered or abandoned their positions.

Still, seizing an enemy trench can be particularly precarious because of the close-quarters nature of the fighting. "Actually jumping into a trench with enemy soldiers is the worst-case scenario, but it has to be done and it happened in the Gulf War," said Staff Sgt. John Meadows, 33, of Roanoke. "We'd prefer not to have to get within three [kilometers] of them -- just blow 'em up with artillery or air power and get going."

Since his company arrived in Kuwait at the end of October, Meadows said, the soldiers have practiced trench-clearing at least three times as often as they would have at their home base at Fort Stewart, Ga. "It's easier for them to take it seriously when we are way out here, away from distractions and staring at the possibility of using it," Meadows said.

Soldiers participating in the drills carried more than 30 pounds of gear. They wore tan and light brown desert camouflage fatigues, flak jackets and Kevlar helmets, and carried canteens. Each soldier also carried an M-16 assault rifle, except for one in each group, who toted an M-240 machine gun. One soldier in each platoon carried a radio on his back to call in artillery from a mortar team located on a sand berm less than a mile from the trench. After dark the soldiers added night-vision goggles, which strapped to the brims of their helmets.

Each day in the field, the soldiers went through the paces in two five-hour training blocks, one beginning in late morning and the other in the moonlit chill of the desert night. Twitty said that although U.S. forces are prepared to fight in any conditions, they have a significant advantage in the dark because of such technology as night-vision goggles and rifle-mounted lasers that allow soldiers to see exactly where they are firing.

Maj. Gen. Buford Blount, the division commander at Camp New York, which lies about 50 miles north of Kuwait City, arrived at Range 7 by helicopter today to watch the trench-clearing exercises. "This was a long week for them, but a great opportunity to practice these things in a tactical environment," he said. "If called on, I am sure they'll be ready to go."

Members of the U.S. Army's 3rd Infantry Division conducted a live-fire assault on a replica of a bombed-out city block in training this week. Soldiers from the 3rd Infantry Division carried more than 30 pounds of gear during exercises in the Kuwaiti desert. U.S. troops have been undergoing intensive training in a recreated urban warfare environment. Troops say the exercises are giving them confidence.