This war has begun in an unexpected way. A preliminary strike at command targets in Baghdad using Tomahawk Cruise missiles and GPS-guided bombs, delivered by F117 aircraft.
Clearly the overall US commander, General Tommy Franks, was given the green light by Washington and London to begin military action at a time of his own choosing.
Intelligence however indicated that it would be worth attacking a number of so-called "leadership" targets ahead of the main assault.
The Chairman of the US Joint Chiefs of Staff, General Richard Myers, has stressed speed and decisiveness; the aim being to knock the Iraqi regime off-balance and to keep it there.
Three elements of the campaign can be identified: an air campaign of great intensity; a psychological warfare assault to convince the Iraqi military that resistance is pointless; and a ground operation to encircle Baghdad.
The hope is that there will be only limited resistance from demoralised and isolated units. Those that do fight will face the full force of American combat power.
And the Iraqi regime, it is hoped, will collapse from within.
Unlike 1991, the air and ground phases of the plan will be less distinct. There could be movement on the ground quite early in this campaign, and if resistance is light, then US and British forces will be encouraged to continue advancing.
The opening phase of the war may look similar to 1991; but appearances will be deceptive. The main onslaught will begin with air attacks against radars, surface-to-air missile systems and command and control centres.
New, so-called E-bombs could be used to destroy electrical circuitry. The aim will be to isolate Saddam Hussein and his senior commanders. There will be fewer targets than in 1991.
But the attacks - especially in the Baghdad area - will be much more intensive and concentrated into a much shorter time period.
Unlike in 1991 when the weather - the worst for over a decade - significantly hampered air attacks using laser-guided weapons, this time they will be carried out with cheaper, and hence more numerous, satellite-guided weapons.
Even many cruise missiles are now satellite guided. These are highly accurate.
But like all man-made technology, precision-guided munitions can go wrong for a whole variety of reasons.
There will be civilian casualties. But the aim of the US and British is to reduce these to a minimum and to reduce damage to the civilian infrastructure to a minimum as well.
They are likely to be clearing up the mess afterwards and responsible for restoring essential services.
Full-scale air attacks against fielded Iraqi forces will depend upon what the Iraqi military decides to do. And this will depend in part on another important element of the campaign: psychological operations.
Their aim is to discourage Iraqi soldiers from fighting and to dissuade their commanders from using chemical or biological weapons.
The US hopes to persuade Iraqi soldiers not to fight
This campaign, using leaflets and broadcasts is well under way. Its effectiveness will only be proven when war actually breaks out.
Within days - some people believe hours - US and British ground forces will be moving into Iraq. Some airmobile units may leap-frog deep into the country.
The bulk of the heavy US and British armour is concentrated on the southern front where a number of water obstacles could pose challenges.
But if the advance is rapid then a key problem will be maintaining their lines of supply.
The US will also want to get significant forces on the ground in northern Iraq as quickly as possible to secure oilfields and to maintain order in Kurdish areas.
Turkey has not yet given permission for the deployment of 62,000 US ground troops along its border with Iraq.
Alternatively US could try to move troops swiftly into northern Iraq either using air mobile forces like the 101st Airborne Division in Kuwait or perhaps flying in troops from elsewhere using airstrips that have already been prepared within the Kurdish-controlled area.
Some former US military officers are warning the US has gathered insufficient forces for a full-scale invasion of Iraq.
In the military world, it is not so much the numbers of troops or tanks that matter, but the way units and weapons' systems are put together to provide what the military call combat power.
The current US and British deployment in the Gulf is actually a rather small force with which to contemplate the invasion of a country the size of Iraq.
Some 250,000 soldiers - half the number assembled for the 1991 Gulf War - actually provides about 150,000 US and British combat troops.
Iraq has an army, albeit of vastly inferior capability, of some 400,000 men. That is why some of the armchair generals are expressing concern.
Of course the great force multiplier is air power.
Outcome not in doubt
Clearly much can go wrong. But the outcome of this conflict is not in doubt. How long it takes and the level of casualties on both sides will depend upon the degree of Iraqi resistance.
But the imbalance between the two sides is stark. Urban warfare, say, in Baghdad could enable the Iraqis to inflict significant casualties on the Americans, but would risk a terrible price in civilian loss of life.
Equally the use of chemical weapons could cause some problems for advancing US and British forces, but they are well-equipped and trained to deal with this environment.
Civilian casualties, however, could be serious if the weapons were used near inhabited areas.