Chemical attacks may mark the last stand

Saddam Hussein is now down to the wire, about to enter the battle for his survival. He has fewer than 100,000 troops, security police and bodyguards he can rely on - he once had an army of more than a million - and about 100 warplanes.

Driven back to the last third of Iraq where Sunni Arabs are the majority, he may soon have to quit the capital, Baghdad, to make a last stand with his tribe in his birthplace, Tikrit on the river Tigris.

Saddam could take the battle to the enemy. He may order one final attack with the chemical weapons used in the 1980-88 war against Iran, and against the Kurds of Halabja exactly 15 years ago. These would be chemicals such as mustard gas and phosgene. But they are hazardous to handle and tricky to move in a hurry to the battlefront. He has put ruthless General Ali Hassan al-Majeed in charge of the southern front to face British and US marines and the 3rd Infantry Division.

Known as "Ali Chemical", Ali Hassan ordered the use of chemical artillery shells against Iranian troops. He knows he has only one shot, then retaliation would obliterate both him and his forces.

VX nerve gas, pioneered by the British in the Fifties, was also used against the Iranians. Saddam's men have just confessed to Hans Blix's UN inspectors that they have more to reveal about their stash of VX, and it could now be used. It requires injections of atropine to neutralise, and this would slow the allied advance. But VX tends to evaporate quickly in the rising temperature, and could be more of a hazard to its users than to its targets.

Nerve agents and other chemicals could be released from crop-spraying planes converted into pilotless drones guided by remote-control radio. However this programme is not thought highly advanced, with few such planes in working order.

Saddam may try to drag Israel into the battle in an attempt to rally Arab states to his cause. He has some Scud B missiles and some effective aircraft to try this. However, the SAS and US Delta Force have been scouring Iraq's western deserts for mobile launchers, and allied aircraft have been bombing the airfields around "H3", the main air command centre close to the Jordanian border. If he decides to shoot at Israel, it will be one shot only. The Israeli air force will hit back immediately.

Saddam's main tactic will be to fire the oilfields, producing pollution and smoke hazardous to allied aircraft and tanks, but a nuisance rather than a big deterrent. It also signals to Iraqis the spite of their dictator, and his contempt for most of them.

In cities and close to his barracks and palaces, Saddam has ordered huge ditches and earthworks to be prepared. The ditches will be filled with burning oil - a tactic his troops used to defend Kuwait in 1991, but to surprisingly little effect.

In cities such as Baghdad and Tikrit, his tactics are likely to be at their most primitive and ingenious. He may resort to suicide squads loaded with explosives, driving or hurling themselves at advancing troops - particularly where there are crowds of civilians. In 1991 some Iraqi soldiers dressed as Americans and fired on fellow Iraqi troops as they were about to surrender.

One of the most effective weapons in cities will be the rocket propelled grenade launcher (RPG). Fired by an infantryman, a direct hit on fuel, tank tracks or ammunition panniers can be devastating. In the "Black Hawk Down" incident in Mogadishu, Somalia, in 1993, RPGs downed two US helicopters and a dozen US Rangers were killed.

Saddam will try to bring the battle to the enemy in Baghdad, and it is the intention of Lieutenant General Scott Wallace of V Corps to keep out. "We don't want house-to-house fighting like Berlin in 1945," he said.