A United States defence official has said moves to ban depleted uranium ammunition are just an attempt by America's enemies to blunt its military might.
Colonel James Naughton of US Army Materiel Command said Iraqi complaints about depleted uranium (DU) shells had no medical basis.
"They want it to go away because we kicked the crap out of them," he told a Pentagon briefing.
If war starts, tonnes of depleted uranium (DU) weapons are likely to be used by British and American tanks and by ground attack aircraft.
Some believe people are still suffering ill health from ammunition used in the Gulf War 12 years ago, and other conflicts.
In the House of Commons in London on Monday, Labour MP Joan Ruddock said a test of the UK Government's pledge to keep civilian casualties to a minimum in an attack on Iraq would include not using depleted uranium weapons.
Apparently anticipating complaints, the US defence department briefed journalists about DU - making it plain it would continue to be used.
Depleted uranium, a by-product of uranium enrichment for nuclear weapons or nuclear reactors, has valuable military properties.
It is very dense, about 1.7 times heavier than lead, and not only very hard but unlike other materials is self-sharpening when it penetrates armour.
The Iraqi authorities claim that DU is responsible for a marked increase in cancers
Used defensively as armour, it tends to make ordinary munitions bounce off.
These properties contributed to the relative success of American tanks against Iraq's in 1991.
For the M1 Abrams tank there is no other option: it uses only DU-tipped shells and has DU armour.
"In the last war, Iraqi tanks at fairly close ranges - not nose to nose - fired at our tanks and the shot bounced off the heavy armour... and our shot did not bounce off their armour," Col Naughton told the briefing.
"So the result was Iraqi tanks destroyed - US tanks with scrape marks."
He questioned the motives of those who challenged US use of depleted uranium.
"Who's asking the question? The Iraqis tell us 'terrible things happened to our people because you used it last time'.
DU has been blamed for a number of leukaemia cases among former Balkans peacekeepers
"Why do they want it to go away? They want it to go away because we kicked the crap out of them, OK?
"I mean, there's no doubt that DU gave us a huge advantage over their tanks. They lost a lot of tanks.
"Their soldiers can't be really amused at the idea of going out in basically the same tanks with some slight improvements and taking on Abrams again."
'Marked increase in cancers'
Cancer surgeons in the southern Iraqi port of Basra report a marked increase in cancers which they suspect were caused by DU contamination from tank battles on the farmland to the west of the city.
But the director of the Pentagon's deployment health support directorate, Dr Michael Kilpatrick, said: "To the question, could depleted uranium be playing a role, the medical answer is no."
Depleted uranium is mildly radioactive but the main health concern is that it is a heavy metal, potentially poisonous.
The likelihood of absorbing it is increased significantly if a weapon has struck a target and exploded because the DU vaporises into a fine dust and can be inhaled.
Dr Kilpatrick said a study that had followed 90 US Gulf War veterans exposed to the dust and to shrapnel from DU rounds in "friendly fire" incidents had found no DU-related medical problems.
Some Gulf War veterans believe DU might have contributed to health problems they have suffered. And it has been blamed for a number of leukaemia cases among former Balkans peacekeepers.
BBC News Online environment correspondent Alex Kirby says scientists disagree about the ability of DU to cause the horrific problems that have been reported.
The World Health Organisation recommends cleaning areas with high concentrations of radioactive particles.
"There is real controversy, and real uncertainty," he said.
There have also been various health warnings. A 1995 report from the US Army Environmental Policy Institute, for example, said: "If DU enters the body, it has the potential to generate significant medical consequences."
Alex Kirby says the Pentagon claim that criticisms of DU come only from Iraq and "other countries that are not friendly to the US" is demonstrably untrue.
"To sum up, I guess the Iraqis have got much worse things than DU to worry about in the immediate future, and any risk to environment and health over the longer term remains unproven and perhaps circumstantial.
"But that does not mean the risk is proven not to exist."