The 10-day-old Persian Gulf war has been one of dramatic Scud missile attacks, flickering bombsight images of exploding buildings and the allies' frustration that the enemy hasn't come out to fight.

That is about to change.What will ensue soon, U.S. military commanders believe, is a grueling ground war that may grind on for months. In sharp contrast to the virtually bloodless war Americans have seen so far, this next phase will be one of terrifying confusion and destruction.

For the dug-in Iraqi soldiers awaiting the assault in Kuwait, and for the young American volunteers who saw the Army as a route to a better job or to college, the war will come as a shock. Neither side has ever experienced the intense firepower or the deadly accurate, long-range weapons of the war to come.

"It is not so heroic as the way we fought even 15 years ago," says Israeli Brig. Gen. Uzi Levtzur, a legendary tank commander of the 1967 and 1973 Middle East wars who has been advising the Pentagon on desert warfare tactics. Levtzur, now Israel's military attache in Washington, cautioned that battle plans are likely to go awry, communications will break down, and many Americans may be killed in error by misdirected American fire.

Meanwhile, on the front lines north of Al Wari'ah, Saudi Arabia, combat troops are growing restless.

"It's no longer if, but when," says Capt. Larry Kinde, looking north across a desert for an invisible line he might soon cross into Iraq.

Kinde speaks for tens of thousands. Army soldiers and Marines constantly point out that no army has every surrendered to an air force.

As they prepare for battle, many of the more than 200,000 American troops who will lead the charge hope aloud that their untested, high-tech weapons will perform as well as the laser- and radar-guided bombs being dropped on the Iraqi forces.

Most Iraqi forces are in heavily fortified positions, and allied ground forces are counting on superior technology to undercut Iraq's defensive and numerical advantages. Many predict it will be the fastest-paced ground battle in history.

"I'm just hoping the ground technology is as effective as the technology in the air," says Col. Ron Rokosz, commander of the 82nd Airborne Division's 2nd Brigade.

But, away from the front, the academicians and experts aren't so sure.

"At first, everyone hoped, and many believed, that the war would be fast-moving, mechanized, remote-controlled and perhaps even rather easy," Paul Fussell, a literary war scholar, recently wrote. He was describing the first months of World War II, but his words seemed to capture the prevailing mood of the opening days of the Persian Gulf war.

"No one wanted to face the terrible fact that military successes are achieved only at the cost of insensate violence and fear and agony, with no bargains allowed," wrote Fussell, who as a rifle platoon leader was severely wounded in France in 1945.

"There's been a feeling, both here and out in the public, that this is all somehow unreal, that we're not really at war," a senior Pentagon staff officer said this past week. "That's going to change in a hurry."

The Pentagon's strategy has been to use heavy bombing to cripple the Iraqi army's combat capability before the allies push ahead with a ground assault. U.S. officials suggested this past week that the bombing might continue for weeks.

But there has been only a dribble of defectors from the Iraqi army, and U.S. intelligence officials say they do not know the extent to which Iraq's fighting ability has been damaged in the intensive bombing raids.

With virtually free reign in the skies, officials from Defense Secretary Dick Cheney on down have said there is no need to rush into a ground war. They say Iraq's military can be severely punished from above with far fewer casualties.

But other senior Army officials have concluded that the bombing is close to achieving all it can, and that the ground war will be launched "sooner rather than later," as one officer put it.

The United States and its allies are poised to attack outmanned and out-gunned. Some 530,000 allied troops, including about 390,000 U.S. Army and Marine ground troops, will be thrown against the 545,000 Iraqis entrenched in Kuwait and southern Iraq. Iraqi forces have some 4,200 tanks, against 1,500 U.S. tanks and about 1,700 British, French, Saudi, Egyptian and Syrian tanks.

The forces of both sides are also bristling with howitzers and cannons, attack helicopters and ground-attack fighters armed with tank-killing missiles and anti-personnel bombs. Both sides have long-range rocket launchers that can fire salvos of a dozen rockets at a time, laying down two tons of lethal fragments over several square miles.

Iraq's arsenal of precision-guided weapons, most of them provided by France and the Soviet Union, make Iraq "the most lethal force the American military has ever faced," says Kenneth Brower, a Pentagon consultant on conventional warfare. But while Iraqi troops may have been battle-hardened in eight years of war with Iran, they have never faced the ferocity of modern high-tech battle, either.

Iraq's strategy is simple: to stay hidden behind the barbed wire, mine-fields, flaming oil-filled trenches and anti-tank barriers it has constructed over the past five months.

Iraqi commanders are expected to use artillery-fired poison gas against attacking U.S. units. Their goal is to trap U.S. and allied forces in a long, bloody conflict that will wear down American public resolve and make Saddam look like a hero to the Arab world.

"If they move, we can kill 'em" with artillery and air strikes, a U.S. Army battle strategist said. "If they stay dug in, we have to go in and pry them out. That will be costly."

U.S. strategy is also simple: a blitzkreig attack around the western edge of Iraqi fortifications in southern Kuwait that would bring thousands of tanks, self-propelled artillery and mechanized infantry troops pouring in behind Iraqi lines, cutting them off from the 150,000-man elite Republican Guards and other Iraqi reserve forces positioned near the Iraqi-Kuwait border.

U.S. Marines are also expected to storm ashore in northern Kuwait, linking up with a British armored division streaking up the coastline.

The U.S. strategy, according to Army planners, is to shock Iraqi troops into catastrophic collapse under simultaneous attacks across the breadth of Kuwait and southern Iraq. Typically, such attacks begin with long-range artillery barrages, followed within seconds by sequential waves of fighter-bombers, attack helicopters and charging tanks.

American infantrymen will ride into battle in personnel carriers or helicopters, dismounting to flush out Iraqi command posts, machine gun emplacements and anti-tank gunners who are firing from foxholes.

William Taylor, a retired Army colonel and West Point professor who directs defense studies at the Center for Strategic and International Studies, estimates that this strategy would likely result in 10,000 to 15,000 U.S. and allied casualties, including 3,700 dead. That estimate is the result of sophisticated computer model based in part on Defense Department data.

Senior U.S. Army commanders acknowledge that the ground war strategy is extremely complex, dependent on split-second coordination and clear communications among thousands of individual units. It requires complicated supply lines for fuel, food and ammunition handled by non-combat units that include women soldiers.

And the strategy has never been tried before.

Last fall, U.S. commanders ran the maneuvers in a sophisticated computer war game in Saudi Arabia, and it went well. But no actual troops were involved.