"This is a war we won't even know has started," says Gen. Lewis McKenzie, the Canadian former chief of U.N. forces in Yugoslavia.

It won't begin with CNN reporters and rockets bursting over Baghdad, he says, "but with throats being cut outside Iraqi oil fields, with the no-fly zones being expanded."

And, yes, it probably has already started: "I'd be a damn poor commander if I didn't have people on the ground right now."

Special Operations forces are indeed already in Iraq, say American military analysts. They're identifying targets, jamming communications and trying to secure the oil fields before Iraqi troops are ordered to torch them as they did in Kuwait in 1991.

An aggressive psychological effort is also underway to persuade Iraqi regional commanders to order their soldiers not to fight and to let civilians know that Saddam Hussein, not the imminent invaders, is the greater threat.

More than 150,000 U.S. troops are already in the region, with more arriving daily, many on commercial passenger planes leased by the military to handle the mass ferrying. Britain has dispatched 25,000 forces and Australia 2,000.

About 1,000 Canadian personnel already in the region could help with naval support, escort and surveillance duties.

When all the forces (275,000 troops or more), all the equipment, all fighter jets and aircraft carriers are in place and Commander-in-chief Gen. Tommy Franks is hunkered down in his command-control centre in Qatar, the actual war will commence. At the time of Washington's choosing.

In a series of press briefings, the Pentagon has outlined its battle strategy, or at least for the early stages.

McKenzie says the full war plan is likely still being run through computer simulations at the army's Wargaming Center at Fort Leavenworth - as it was before Operation Desert Storm in 1991 - and won't be divulged publicly.

But giving out details of the initial stages is clearly calculated to intimidate Iraq.

What is known is that the invasion will begin with a huge show of force - 48 hours of massive air bombardment during which 3,000 precision bombs and missiles will be unleashed by air force and navy jets carrying 16 one-tonne, satellite-guided bombs. B-1 stealth bombers will carry 24 of the all-weather smart bombs, called JDAMs.

The targets? Iraq's air-defence network, depleted after the 1991 Gulf War and much of it moved to Baghdad and environs, as well as communication centres, suspected chemical and biological weapons-storage sites and the known Scud-missile ranges in western Iraq.

U.S. forces have been instructed to swiftly disable, but not destroy, Iraq's electrical, water and transportation systems. Unlike in the Gulf War, the military has the technical wherewithal to do it, dropping carbon filaments into the power grid, for instance, to short it out, rather than wipe it out. Post-war stability can then be quickly reinstated.

"The challenge in the air campaign is to achieve certain military and psychological effects at the outset, but have as much of the infrastructure existing when it's over," air force Gen. Ronald Fogleman told the New York Times last week. And much of the population, too, he might have added.

In his State of the Union address last month, President George W. Bush pledged to spare civilians "in every way we can." Observers say the U.S. is serious about that, not wanting to alienate the people it considers itself to be liberating.

The key goal of the blitzkrieg is to undermine the Iraqi troops' will to fight, inducing them to defect in the field, while their top leadership remains isolated in Baghdad. Saddam's regular soldiers surrendered in droves in 1991. The U.S. is counting on a repeat, but this time, unlike last, prisoner-of-war facilities will be ready and waiting.

Almost simultaneously with the air attacks, a massive ground invasion will begin from two directions: one armoured division driving north from Kuwait, the other south from the mountainous Turkish border.

They and airborne troops will be outfitted with new digital communications systems, night-vision goggles and high-tech equipment that, like the JDAM, hadn't been developed last time around.

Among the new developments are microwave weapons that can knock out enemy computers and cluster bombs that scatter titanium rods on impact to burn up storage tanks of chemical weapons or neutralize biological toxins with disinfectants.

Ahead of the lines of advance, special army units and Marine expeditionary forces will attempt to capture key posts, preventing Iraqi troops from obstructing the armoured assault by blowing up dams and dikes and flooding the Euphrates and other rivers.

The sheer size and speed of unrelenting and precise air and ground attacks will snowball in effect, igniting a rapid collapse of the regime and convincing Saddam to accept the inevitable.

On paper, it should be a walkover. Iraq's military equipment - its tanks, artillery and air force - has declined by more than half since 1991 and has become worn out or obsolete after a decade of U.N. sanctions on spare parts. American and British jets patrolling the no-fly zones over northern and southern Iraq have knocked out many of Saddam's air defences.

"People talk about this being a cakewalk," retired air force Gen. Richard Hawley told reporters last week. "The fact is, Iraq still has several thousands of troops that have had months to prepare themselves."

Not to mention an unpredictable leader with several wild cards in his possession.

As he did in the last war, Saddam could turn millions of his people out of their homes, creating a stream of refugees to slow down the ground invasion. He could explode Iraq's oil fields right at the start or destroy his own infrastructure, launching a scorched-earth strategy significant enough to stop a military advance in its tracks.

Analysts say the biggest threat in this pre-war period is that Saddam will launch a pre-emptive strike either against Israel or U.S. troops now stationed in Kuwait.

It's believed he has enough chemicals and biological agents to arm missiles that are capable of reaching both targets.

"Saddam's best tool is to try to scare the West in advance because his forces are likely to fold like a deck of cards once faced with real military power," argues Loren Thompson, an analyst with the Lexington Institute defence think-tank in Arlington, Va.

Canada's McKenzie doesn't agree: "He'd be vaporized if he made a pre-emptive strike."

It's safely assumed, however, that Saddam won't repeat his big Gulf War mistake: taking on a superior military force in the open desert and getting crushed in the process. Instead, he'll try to draw the U.S. and its allies into Baghdad, where the advantage will revert to his Republican Guards stationed there.

Although it has trained special units for street-to-street fighting, urban warfare is the Pentagon's worst-case scenario.

Technological superiority is negated if U.S. troops are forced into street battles against Iraqi soldiers who know the city and will be disguised as civilians - amidst 5 million of the real thing, some of them also armed and in citizen militias.

"Urban fighting will eat up troops and force them to disperse," says David Rudd, executive director of the Canadian Institute of Strategic Studies. "Even a few determined Iraqi snipers could hold up an advance into the city."

Rudd has talked in recent days with U.S. officers who say that, if forced into street fighting, the approach will be different from that taken in past conflicts. "Then, if someone spotted a machine gun in a window five floors up, three to the left, everyone would start busting caps. This time, they've been trained to close in on the building and get him from within."

U.S. troops might also "mouse-hole," says Rudd; that is, stay off the streets, where they are in the enemy's full view and range, and instead blow holes in the walls of houses to advance through them one by one from the inside. Only problem is, Rudd notes, "Saddam is likely to have booby-trapped them."

But the U.S. wants to avoid the high casualties of urban warfare if at all possible. If not - if Saddam forces Baghdad to hold out - it's believed central command will order that the city be surrounded and besieged, with escape lines opened for civilians and defectors.

According to retired Adm. Stephen Baker, special adviser to the U.S. Center for Defense Information: "Many days of intense combat and many failed tactics would have to have occurred before military leaders decide that U.S. forces should be heavily engaged in urban warfare."

For that to happen, Saddam may have to confront his own worst-case scenario - an internal coup that will see him being taken out by one or more of his generals.

Analysts say he enjoys little trust, even at the highest levels of his military and security inner circle. His two Republican Guard and "Special" Republican Guard units, consisting of 100,000 of his allegedly most loyal soldiers, weren't tested in the Gulf War because Saddam's removal wasn't an objective.

This time, it is. Will the Republican Guards go down fighting on his behalf when the giant American push comes to shove? Or will they sense that submission is the smarter part of valour?

They're his Praetorian guard, says Rudd, and just like the Roman originals, they could easily stick a knife into Caesar's back when someone more powerful is knocking at the door.

It could work out that way, but the United States is risking the world's condemnation if Gulf War II isn't the swift, surgical, six-weeks-at-most operation it's speculated to be.