US leaders have warned that the war is not yet over but it was the same White House and Defense Department officials and experts that had predicted the worst before the conflict started March 20.

There could be new September 11 terror attacks on the United States, thousands of health workers and military were vaccinated against smallpox, retired generals warned that Iraq could become a new Vietnam.

But after just three weeks of war, the US army now controls most of Baghdad and the battle for the city has moved forward without the degree of vicious street-to-street fighting feared by American military commanders.

Saddam's Republican Guard and the Fedayeen paramilitary militia headed by the president's son Uday, have not proved the fanatical fighting force their reputation had suggested.

Colonel Mike Turner, who was an aide to General Norman Schwartzkopf, the US military commander, during the 1990-1991 Gulf War, told of his nightmare during a debate on National Public Radio.

"Within hours of our attack, Saddam launches Scuds on Israel. Israel's right-wing government launches a full-scale attack on Iraq, creating a holy war nightmare."

But US troops quickly took control of western Iraq and Defense Secretary Donald Rumsfeld said the progress toward Baghdad over the past three weeks had been "spectacular".

Equally absent have been apocalyptic scenarios of attacks using biological, chemical or nuclear weapons.

In early February, Bush also evoked the risk posed by a pilotless aircraft being used by Iraqis to spread dust impregnated with anthrax over US forces.

"Clearly, the administration was on the impression that chemical-biological (weapons) could be used," said Patrick Garrett of military analysts GlobalSecurity.org.

Garrett suggests that "some Iraq military, the ones who were in a position to pull the chemical trigger, they thought that maybe this is not such a great idea."

To disseminate smallpox virus, anthrax or VX gas more efficiently, the Iraqis could have used Ababil rockets, Scud, Al-Hussein or Al-Samoud missiles, even Iraqi artillery, according to Anthony Cordesman of the Center for Strategic and International Studies, speaking in early March.

Cordesman had raised the specter of Iraqis blowing up their own oil wells, provoking an ecological disaster in tandem with an escalation of the price of oil to severe economic repercussions all around the globe.

The White House had noted back on March 28 that oil prices had even fallen during the conflict after the fears failed to materialize.

The possibility of a major humanitarian crisis has also been sidestepped, despite civilian casualties in Iraq.

Even though thousands of people have headed towards Jordan and Iran to avoid US and allied bombings, the figures are well below the hundreds of thousands -- or even millions -- envisaged.

Another potential "catastrophe" for the Bush administration also seems for the moment to have been avoided. The US public have not turned their backs on him, with polls reporting more than three Americans in four still support him.

SPACE.WIRE