Getting closer by the hour: the most intense aerial bombardment the world has ever seen

If the US – with a little help from Britain – cannot win this Gulf war with the use of air power alone, it will not be for want of effort.

US-led coalitions have previously gained the upper hand in Kosovo and Afghanistan almost entirely from the air. Now they are aiming higher: seeking to use every ounce of their military and technological superiority to try and remove Saddam Hussein from power without the use of ground forces, if at all possible.

Military strategists have spoken of firing 3,000 missiles in the first 48 hours, their accuracy enhanced from the previous war by the use of global positioning systems (GPS), in an intensive assault aimed at demoralising and dividing the Iraqi regime to the point at which it might collapse of its own accord.

Inevitably such a strategy will focus on Baghdad, the heart of the regime's power. Targets can be expected to include the Republican Guard and Special Republican Guard divisions ringing the capital, as well as buildings regarded as symbolising Saddam Hussein's rule, such as ministries, military headquarters and possibly his palaces.

Bridges across the Tigris were blown up in 1991 and could be destroyed again if the military planners regard it as achieving the objectives set by the no-nonsense US Defence Secretary, Donald Rumsfeld.

Other targets could include weapons sites known to UN inspectors, or facilities that could be used to produce weapons of mass destruction. The US and Britain singled out such targets to degrade Iraq's weapons of mass destruction during the 1991 Gulf War.

Missiles will be fired from surface vessels and submarines in the Gulf and Red Sea, as well as being launched from B-52 bombers flying from Fairford in Gloucestershire and Diego Garcia in the Indian Ocean. More than 500 strike aircraft, including 70 from the RAF, will fly from carriers in three seas and bases in several Gulf countries, joined by B-2 Stealth bombers from as far away as the US. The threat will be augmented if Turkey's parliament votes today to approve the government's decision to allow overflights by aircraft on their way to attack Iraq.

In the 1990-1991 Gulf War only 10 per cent of air-dropped munitions were "smart" – guided to their target by lasers – and 90 per cent "dumb".

Now the proportions have been reversed with GPS satellites making it possible to locate targets in darkness or bad weather. Iraq's air defences, already eroded by months of attacks under cover of the northern and southern "no-fly" zones enforced by the US and Britain since 1992, are far weaker than last time.

This is one compelling reason why the air campaign is expected to be shorter than in 1991, when it lasted six weeks, but it is by no means the only one.

Greater accuracy, in the view of military theorists, brings a greater responsibility to avoid civilian casualties, but as the Pentagon learnt to its cost 12 years ago, it does not pay to portray its munitions as infallible. Even if they are pinpoint accurate, a failure of intelligence can cause disaster, as when the Chinese embassy in Belgrade was destroyed during the Kosovo campaign.

The longer a city like Baghdad is attacked, the greater the chance of a propaganda gift to the Iraqi regime like the missile that hit the capital's Amariya bunker in 1991, killing 408 civilians. Not even the media manipulators of Washington, their techniques also enhanced in the past decade, would be able to spin away such a tragedy.

But the main reason for a brief period of bombing is the change in military thinking in the past decade, and particularly since Mr Rumsfeld took office. He threw out the first plan drawn up for this war by his military staff, which was essentially to repeat the last one: assemble a massive military force, but delay an invasion until a prolonged bombing campaign has pulverised Iraqi defences.

Mr Rumsfeld has been persuaded by the arguments of a new school of military strategists, who favour fast, mobile, hi-tech forces. With US weapons "smarter" and Iraqi forces weaker than they were last time, say these experts, the air preliminaries can be cut short. Proponents believe land and air campaigns can begin simultaneously, and some argued for an "inside-out" strategy designed to seize Baghdad and decapitate the Iraqi regime, or at least cut it off from the rest of the country. But that was rejected by the top brass.

The strategy being adopted is a compromise. The build-up has been longer than Mr Rumsfeld might have liked, and is still not complete, due mainly to the uncertainty caused by Turkey's refusal to allow US and British forces to land on its soil. But at some 250,000 personnel, it is only half the size of the force deployed in 1991.

Commanders say they can begin the invasion even before the final elements arrive, in what they call a "rolling start"; even if this is an exaggeration designed to keep their Iraqi counterparts guessing, there is nothing to prevent the air campaign getting under way.

Yesterday there was a spate of reports that ground forces were on the move. If any of the reports are confirmed, it will be clear that Mr Rumsfeld has triumphed over the caution of his commanders, and that in this war, land, air and sea operations will be all but seamless.