Precision air strikes to destroy morale
The air campaign unleashed by the US aims to break the morale of the Iraqi military.
The long-awaited move began on the third night of the war, with US cruise missiles and carrier aircraft precision bombs raining down on Baghdad and other major cites.
It is part of the campaign to destabilise the Iraqi military and force it to surrender.
And, as well as its military effects - aimed to destroy the command-and-control centres that control the Iraqi war effort - it is a big part of the psychological campaign aimed at ensuring a quick victory.
"The confusion of Iraqi officials is growing. Their ability to see what is happening on the battlefield, to communicate with their forces and to control their country is slipping
away," said US Defence Secretary Donald Rumsfeld.
The US has already dropped thousands of leaflets urging soldiers not to flight for Saddam Hussein, and has tried to communicate with military commanders in the field to encourage them to surrender.
Will it cause the Iraqi army to surrender?
The doctrine of "shock and awe" is based on a book by military strategist Harlan Ullman, who is admired by both Defence Secretary Donald Rumsfeld and Secretary of State Colin Powell.
Mr Ullman wrote that the use of air power to achieve "nearly incomprehensible levels of mass destruction" could achieve "an overwhelming level of shock and awe against an adversary on an immediate basis to paralyse its will to resist".
It is a belief that is deeply held by the US military, who were among the first advocates of strategic air power.
They applied it to the destruction of Hiroshima and Nagasaki which ended World War II.
And it was deeply held by the first advocates of air power in the early 20th Century, including early British and Italian military theorists like Sir Hugh Trenchard and Giuilo Douhet who believed that civilian morale would collapse with the first air strikes on cities.
However, many US supporters of air power have called for precision bombing which would not be aimed directly against civilians but only military and industrial targets.
Mr Ullman argues that with modern precision weapons, a "non-nuclear equivalent" of Hiroshima could be created.
The use of these sophisticated weapons, precisely targeted by global positioning satellites, is designed to maximise their effects while limiting collateral damage, which would make the task of post-war reconstruction more difficult.
Mr Rumsfeld said that there was no comparison between the air war in World War II, where "dumb weapons were widely distributed across large areas," and the precise targeting employed now to ensure that military targets and the leaders of the regime were precisely attacked without harming the Iraqi people.
The US military hopes, that with the Iraqi Government under attack and unable to communicate with its troops, the fear of further massive attack will lead to a collapse of the regime and widespread surrender.
But history shows that air campaigns will only work if morale is already undermined.
At the beginning of World War II, the Germans helped insure a rapid surrender of the Netherlands by the terror bombing of Rotterdam, but the German attacks on London and other cities in the Blitz hardened British resistance.
And in Vietnam, large scale bombing also seemed to have little effect on enemy morale.
But US officials believe that there is no widespread support for Saddam Hussein's regime, and that they have already gained the psychological advantage over their enemy.
"The Iraqi regime is history," Mr Rumsfeld said.
"The Iraqi people are an oppressed people," he added.
And, as he did in his first press conference, he appealed directly to the Iraqi military to surrender.