U.S. Training for Big Desert Tank Battles : Military: The exercises emphasize speed and maneuverability that commanders say would be essential against Iraqis.

U.S. military forces, anticipating that the effectiveness of tank battalions could be the deciding factor in a ground war with Iraq, have begun extensive training exercises in the vast desert plains to simulate a mechanized battle of unprecedented scope.

The exercises, involving armored Marine units based near the Kuwaiti border, represent the most detailed rehearsals the United States has conducted here so far for a possible clash against Iraq and its 3,500 tanks stationed across the border from U.S. forces.

The operations by the Camp Pendleton-based Marines, observed by reporters for the first time Friday, emphasize tactics of speed and maneuverability that U.S. commanders say would be essential in any operation against Iraqi forces in the virtually limitless desert battlefield.

“The way we see a battle being fought here is essentially the way the Navy would fight in the middle of the ocean,” said a high-ranking U.S. tank commander. “You cannot fight a static battle out here in this massive terrain.”

Military commanders say the deployment of tanks and other armored forces is likely to determine the outcome of any ground engagements between U.S. and Iraqi forces should the current Persian Gulf standoff escalate into an all-out shooting war.

Despite Iraq’s numerical advantage, U.S. officials are confident that American tanks and tactics are far superior to those of the opposition. Iraq’s forces have been tested only against the Iranians, who had virtually no ability to mount large-scale armored operations during their eight-year war with Iraq.

In contrast to the Iraqi forces dug in north of the Saudi-Kuwaiti border, the scores of U.S. tanks here remain in highly mobile positions as part of a flexible defense strategy that top Marine generals said would be designed to combat an Iraqi offensive with a massive counterattack.

At the same time, Marine and Army tank officers said in interviews at three separate front-line units this week that they had begun a detailed study of the defenses and tactics used by the Iraqi tank units in preparation for a possible U.S. offensive against them.

In separate interviews, however, the Marine generals declined to discuss a prospective attack, noting that their mission remains to defend Saudi Arabia. But they made clear that if hostilities were to break out, with thousands of tanks now arrayed across both sides of the front, the wide-open terrain would see mechanized warfare on an epic scale.

“Mobility is the key,” said Brig. Gen. James M. Myatt, commander of Marine ground forces here, who said he envisions a high-speed race for position by vehicles from both sides. “Things happen faster in a highly mobile environment.”

But, noted Lt. Gen. Walter M. Boomer, commander of all Marines in Saudi Arabia, “It’s not just dancing around the desert.

“Ultimately you’re going to bring your combat power with the greatest concentration that you have at his weakest point,” Boomer said. “And you hit him hard. That will be a very, very fierce battle as I see it.”

The U.S. armored units deployed here--particularly the Pendleton-based 3rd Marine Battalion involved in Friday’s exercise--have been schooled extensively in desert warfare at the National Training Center at Twentynine Palms.

But tank commanders say the sheer vastness of the desert terrain in Saudi Arabia creates conditions for an armored battle far more fluid than anything they previously rehearsed. And while U.S. mechanized units fought in North Africa in World War II, the commanders say the ferocity of a tank battle here would be unprecedented in U.S. experience.

“Vietnam was low-mech and low-intensity,” said Maj. Mike Vrabel, an armored-infantry commander from Los Angeles. “This war will be high-mech and high-intensity.”

In ordering the extensive exercises along the U.S. lines, Boomer said he was taking advantage of a “luxury” of the withdrawal from the Iraqi front of elite Republican Guard units, regarded by military officials as a sign that no attack is imminent.

The mock battles, expected to build to a battalion-size clash next week, were described by Marine commanders as a vital step in honing their armored forces for possible combat against an Iraqi force to which the U.S. military had previously devoted little attention.

At the same time, however, the Marine exercises underscore the relative lack of readiness of the Army’s heavy armor units, whose M-1 tanks are the most powerful in the U.S. arsenal. The bulk of these tanks have not yet arrived in Saudi Arabia, and commanders have not yet begun training with those already in the country because of shortages of supplies.

In Friday’s exercise, small armored infantry vehicles responded to a simulated Iraqi attack by charging at more than 40 m.p.h. across the desert in hopes of spotting the enemy column as it barreled toward the U.S. lines.

After sighting the telltale cloud of dust from more than 5 miles away, the unit called in simulated artillery strikes on the “Iraqi” forces, while trailing U.S. tanks moved forward to engage the column from as far as 2 miles away.

Top Marine commanders emphasized that in the event of war, such an attack would be bolstered with support from the air as F/A-18 Hornet attack planes and helicopters equipped with anti-tank missiles rained down fire from the sky.

“The human being can only deal with so many things at one time,” said Boomer, the Marine commander in chief. “We’re going to present him with a large number of problems to deal with simultaneously--from three dimensions.”

But if the air strikes were to prove inadequate, commanders said, the tank war would probably prove to be the equivalent of a one-shot duel.

“The key to it all is finding them as early as possible and bringing the battle to them on our terms instead of letting them take it to us,” said Lt. Matthew Chisolm, a 26-year-old tank platoon leader from Laramie, Wyo.

“Basically,” Chisolm said, “whoever gets the first shot on target is going to win.”

Times staff writers John M. Broder and Maura Reynolds, in Washington, contributed to this report.