THE crucial push for Baghdad began last night as allied warplanes bombarded the Republican Guard to clear the way for troops to zero in on President Saddam Hussein.

The American vanguard was within 20 miles of 30,000 Republican Guards defending a city blanketed in black smoke from pyres of burning oil. Thousands more allied troops were rushing north to form a front line for the battle that will decide the war.

Yesterday the Republican Guard’s Medina Division was pummelled continuously by bombers working on information from SAS, SBS and Delta forces close to Iraqi positions.

American generals said that the air raids, involving B52s, Apache helicopter gunships, Harriers and A10 tankbusters, had “significantly degraded” the division, but one helicopter was lost. Iraq claimed to have shot it down and state television broadcast pictures of the helicopter in a field and the two men said to be its crew. They appeared confused but unharmed.

The “softening up” of the Republican Guard is expected to continue for days, but air operations could be disrupted by violent sandstorms, which halted American infantry divisions near Karbala yesterday. Military planners have been told that the “shamal” desert winds are likely to whip up further sandstorms.

Tony Blair told MPs yesterday that the forces gathering at Karbala were preparing for the “crucial moment” when they would confront the Medina Division. Brushing aside concerns that supply lines were becoming dangerously stretched, he said: “The vital goal is to reach Baghdad as swiftly as possible, thus bringing the end of the regime closer.”

It may, however, be necessary for more troops to be sent to the Gulf if the forces there become bogged down in urban warfare, and the possibility of sending reinforcements will almost certainly be considered when Mr Blair and President Bush meet in Washington on Thursday for a summit arranged to discuss the administration of a post-Saddam Iraq.

The Iraqi leadership remained insistent yesterday that there would be no such thing. Saddam appeared on television promising victory and Tariq Aziz, the Deputy Prime Minister, countered Washington’s claims that the dictator’s grip on power was slipping by saying that Saddam was “in full control of the army and the country”.

If America and Britain want to change that, their forces will first have to overcome the three Republican Guard divisions that are dug-in 30 miles to the east, south and west of the centre of Baghdad. “They are those closest to Saddam and they will resist strongly,” Mr Blair said. A British military source said: “These people have got to capitulate or be destroyed. This is the real start of the push for Baghdad.”

The coalition strategy is to establish a front line stretching eastwards from Karbala across the two main highways into the capital. The line will remain fixed as waves of air and ground-launched missiles pound the Republican Guard while the heavy artillery and tanks of V Corps rumble up for an eventual land assault. By the time that is launched the coalition aims to have 60,000 combat troops, 400 Abrams M1 tanks and 100 Apache attack helicopters massed on the front. The Republican Guard divisions have 500 tanks.

To help the push northwards, American forces pounded the strategic town of al-Nasariyah with heavy artillery yesterday and moved a light armoured battalion through the town and across the Euphrates, opening a second route to Baghdad. US engineers were also working to finish a new desert airstrip near Najaf in central Iraq, which would allow unmanned Predator drones to patrol the skies over Baghdad and gather vital information about Iraqi forces.

The thrust towards Baghdad came despite continued Iraqi resistance in the south, sparking warnings that coalition supply lines were becoming vulnerable to attack from marauding bands of Fedayin militia.There was fierce fighting around Basra, where the allies secured an airport and an important bridge. Coalition forces are, however, banned from storming residential areas.

Elsewhere in the south, groups of militia used civilian pick-up trucks to launch mortars and rocket-propelled grenades attacks on supply convoys. US Marines, chastened by the ambushes and trickery that led to the deaths and capture of American forces near al-Nasariyah on Sunday, were forcing men from vehicles, questioning them and slashing their tyres so that they could not harass convoys.

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