FORT IRWIN, Calif. - Under cover of darkness, hundreds of paratroopers from the 82nd Airborne Division descend onto a remote desert airstrip, quickly seizing it from enemy forces.
As they scramble to set up a perimeter defense, soldiers flip open laptops that display the precise location of the enemy.
Other soldiers in swift-moving armored vehicles seize a chemical weapons depot and later a surface-to-air missile site, threats they would likely encounter in Iraq.
The captured airfield is at this California training range, and soldiers in the three-week training operation called Millennium Challenge are testing the latest military technology under rugged, if not actual battlefield, conditions. Officers expect the exercise to provide useful lessons should President Bush decide to invade Iraq.
While soldiers train in this Mojave Desert range, a hilly and parched swath of land the size of Rhode Island, the war drums in Washington grow louder by the day. And so does the debate over how that war should be conducted.
Three widely differing plans for defeating Iraqi President Saddam Hussein have surfaced publicly. And officials say a number of others are under consideration.
The debate has pitted the civilian Pentagon leadership, presided over by Defense Secretary Donald H. Rumsfeld, against some senior members of the uniformed military.
At the heart of the dispute is a disagreement over the number of U.S. troops that would be needed to topple Hussein, the degree of logistical support required and the capabilities of U.S. air power.
Playing into the argument is an array of new high-tech weaponry and equipment, much of it battle-tested in Afghanistan.
Officials must also contend with a number of issues that could determine the final plan of attack, including the support, or lack of it, from neighboring states such as Saudi Arabia and the degree to which a loose coalition of Iraqi opposition groups can be counted on in combat.
Finally, planners formulating their battle scheme must weigh the degree to which Hussein can expect his army of about 400,000 - including a core group of 100,000 elite Republican Guard troops - to rally around him.
The war plans and the debate:
A three-pronged attack from Kuwait, Turkey and Jordan with 250,000 U.S. forces that was first devised during the Clinton administration by the U.S. Central Command in Tampa, Fla., which has responsibility for the region.
Defense officials and military analysts said the plan is a classic Army proposal, a huge mixture of light and heavy forces to overwhelm an enemy and reduce risk, much as the former CentCom commander, Gen. H. Norman Schwarzkopf, employed during the 1991 Persian Gulf war.
But military officers said that Rumsfeld and his senior staff bristled at that plan, which was offered by the current CentCom commander, Gen. Tommy Franks, saying it was unimaginative and would take too long to put into place.
In Rumsfeld's view, the situation with Iraq does not require a strategy like the one used to fight the gulf war, where the buildup took six months and included more than 500,000 U.S. troops.
Some critics also warn that Hussein could use the buildup time to strike at Israel, other U.S. allies or the assembling American forces with missiles armed with chemical and biological warheads.
One defense official said Rumsfeld and his aides were frustrated by the lack of creativity and high troop levels in the Franks plan. "They simply said ... your numbers are unacceptable," the official said.
An enormous U.S. air campaign that would be followed by a combination of 50,000 U.S. and Iraqi opposition forces, somewhat similar to the strategy used in Afghanistan.
The attackers would target Iraqi troops and capture large areas of territory, aided by Iraqi opposition fighters, who would also be used for intelligence gathering and to persuade Iraqi army officers to defect. Under this plan, Kurdish troops in the north would also take part in the fight.
But critics say Iraq is too formidable a foe for that number of troops. They also say the Iraqi opposition does not have enough skilled fighters and doubt that there is enough time to turn them into an effective force like the Northern Alliance that fought side by side with U.S. forces in Afghanistan.
Precision air attacks and troop assaults on key command and control sites in Baghdad as well as nearby chemical and biological sites. The plan, known as both "Baghdad First" and "Inside-Out," and first reported by The New York Times, would require 80,000 to 100,000 troops.
The plan is seen as a way to quickly cripple Hussein's command and control system, perhaps killing the dictator and top officials, leaving Iraqi troops rudderless. Moreover, the proposal calls for neutralizing what is seen by some as a prime threat to U.S. forces and its allies, the chemical and biological weapons facilities.
But critics argue that exquisitely detailed intelligence is needed to strike the critical targets inside the city and elsewhere, and Pentagon officials say that some of Hussein's chemical and biological weapons are buried or cruising around in mobile labs.
Capturing or killing the Iraqi leader, who is also constantly on the move, is hardly guaranteed. He might also shift his command centers to secret locations, the plan's detractors say. Such an attack could also lead to extensive civilian casualties and inflame public opinion, particularly among Arabs.
Furthermore, if the assaulting force failed to achieve its objectives speedily, more ground troops would be needed and U.S. forces could get bogged down in urban fighting, historically a high-casualty situation that armies have sought to avoid since ancient times. And Hussein's most loyal troops, the Republican Guard, are thought to be well trained in urban combat.
One point of contention centers on the degree to which air power can be effective, with Rumsfeld and his top advisers said to be putting much of their faith in precision bombing.
During the gulf war, precision bombs made up about 7 percent of all the ordnance dropped in Iraq, a figure that rose to 80 percent in Afghanistan. As of May, Boeing was producing each month 1,500 Joint Direct Attack Munitions, one of the prized U.S. precision weapons. Boeing expects to increase the number to 2,000 a month by the end of the year.
But senior Army officers are wary of any plan that calls for what they consider too few troops, which they say translates into an unacceptably high risk. "We're responsible for the lives of our soldiers," said one officer, who asked not to be named.
Some in the Army fault Rumsfeld for placing too much emphasis on what the Air Force can deliver. "But what if they don't?" asked the officer.
No matter what plan finally is chosen, the Army insists on a minimum force of three heavy divisions and an airborne division, between 75,000 and 100,000 soldiers, the officer said.
That number does not include the tens of thousands of Marines and possibly British forces likely to participate in the action.
"You have to assume the Republican Guard will fight pretty hard," said Michael O'Hanlon, a defense analyst at the Brookings Institution, who said defense planners appear to be moving toward the troop level favored by the Army. "You want to have comparable numbers of forces to the numbers you're fighting."
A key issue for the Pentagon is determining where U.S. and allied forces would launch an invasion. Saudi Arabia, where about 5,000 U.S. troops are based, was used for the 1991 war but has ruled out the use of its territory this time, as has Jordan. U.S. forces are also stationed in the neighboring countries of Kuwait, Bahrain, Oman and Qatar.
Saudi officials have not yet said whether Saudi airspace could be used, a key point if Navy carrier-based warplanes are to be employed. Turkey, meanwhile, has been noncommittal about its support for a U.S. attack.
The Pentagon has contingency plans to move its high-tech military command post in Saudi Arabia to Qatar if Saudi officials do not allow its use in a war with Iraq.
Should the president order an attack, the chief threats awaiting the invaders, in addition to Iraqi ground forces, include a sophisticated air defense system and possibly chemical and biological weapons.
Top Pentagon officials have provided classified briefings to Congress and European allies on Hussein's progress in developing weapons of mass destruction. They also have pointed to it as a primary reason for the president's policy of "regime change."
Some defense analysts and military officers, however, say the threat is overblown, arguing that the stockpiles are limited and the agents difficult to use as weapons.
But Khidir Hamza, who was part of Hussein's weapons program before defecting in 1994, is more wary. During the gulf war, he says, the Iraqi dictator planned to employ chemical and biological weapons against allied forces if they reached the gates of Baghdad.
In the California desert, Maj. Michael Kasales, a burly 37-year- old operations officer for one of the Army's cutting edge reconnaissance squadrons from Fort Lewis, Wash., recalled how his unit helped seize the chemical weapons site and the surface-to-air missiles.
It deployed a high-tech detection vehicle to make sure that no poisonous clouds were wafting toward the troops. The squad also used unmanned drones that can hover in the sky and spy on an enemy, as well as tiny ground sensors that can reveal troop or tank movement.
Standing under a protective camouflage netting, Kasales said he raised the possibility of Iraq with his fellow officers, wondering if their new-found skills would be called to war. He is confident of the outcome. "We could accomplish our mission," he said.