Iraq's early warning and air defence systems have been ground down by a dozen years of air attacks by coalition forces.
Coalition aircraft filmed an Iraqi missile launcher turning towards them
Yet the attacks keep happening - and were intensified before the invasion - because Iraq keeps on repairing what its official news agency calls the "heroic missile forces and brave ground-to-air defences".
The Iraqis routinely fire surface-to-air missiles and artillery at American and British warplanes patrolling the so-called "no-fly zones" over northern and Southern Iraq.
One of its two missiles is fired ...
American officials have said there were almost 500 such attacks during 2002.
The Iraqis have never managed to hit coalition fighter jets, although in July 2001 the pilot of an American U-2 spy plane reported feeling the shock wave from an exploding missile while flying over southern Iraq.
This was regarded as significant because the U-2 flies at very high altitude.
... and streaks away from the launcher
Iraqi analyst Dr Mustafa Alani, of the London-based Royal United Services Institute, said this might suggest a relatively sophisticated system.
"Either the system was very effective - or it was just by luck, because it hasn't happened again."
Iraq did bring down an unmanned US Predator reconnaissance plane in 2001 - claiming this was as a result of having upgraded its defences.
It is also reported to have downed three unmanned Iranian reconnaissance craft being used to look for Mujahideen Khalq rebel bases inside Iraq.
According to the military think tank GlobalSecurity.org in Washington DC, Iraq has perhaps 2,000 surface-to-air missiles (SAM) of different types, as well as thousands of anti-aircraft guns.
But the missiles are mostly "antiques" according to Dr Alani.
He said the original four-sector air defence system, controlled from Baghdad, was largely obliterated during the last Gulf War, and essentially only the central sector around the capital remained.
He said anti-aircraft artillery and SAM sites had been situated in residential parts of the city, making them difficult to hit from the air without causing civilian casualties.
The Iraqis have also been inventive in adapting what they have.
Images released by the US Department of Defence have shown Soviet-made S-125 SAMs, originally made for fixed launchers, mounted in pairs on the back of a truck - and being fired at coalition aircraft in southern Iraq.
Iraq's repairs to its overall control system are said to have included the installation of fibre optic communication cables.
These were allegedly of Chinese origin - though both China and Iraq denied press reports to that effect.
British defence sources have also said that Serbia, under the former President Milosevic, helped to rebuild underground air defence facilities in Iraq.
Last year US Air Force general John W Rosa told journalists: "The Iraqi air defence system is one of the toughest, most complex systems that we see in the world.
"It's very capable. They're constantly working to improve it, and they have been."
He declined to characterise its current capability.
"It's rubbish," according to Andrew Brookes, an air specialist at the International Institute for Strategic Studies in London.
And whatever was left would be "hit with a vengeance" within 30 minutes of any attack on Iraq starting, he said.
"All the aircrew who are out there have been practising in that region for years - it'll be like going back to training."
Change of focus
One risk is that the Iraqis might succeed in using decoy radar emissions to "seduce" US and British warplanes into attacking something like an old people's home.
"Then of course they get the propaganda value," Mr Brookes said.
"So I'm not trying to pretend it's a walkover in the sense that there won't be innocent civilian casualties.
US leaflet dropped on Iraq: "Don't track or fire on coalition aircraft"
"But if the question is, 'is it going to be a long-fought war to secure air superiority in the conventional sense?' the answer should be 'no'."
The US Defence Secretary, Donald Rumsfeld, said that following a review of tactics last year, coalition aircraft began going after fixed targets rather than mobile anti-aircraft sites.
But he said no-one could say whether the Iraqi defence system was being degraded faster than it was being improved.
During 2003 the coalition air patrols have been stepped up.
American officials were reported as saying US and British warplanes had more than doubled their patrols over the no-fly zones to at least 500 a day.
The Ministry of Defence said in March that its aircraft were patrolling the southern zone "round the clock" so RAF aircrew newly arrived in the area could get experience.