Christopher Bellamy: Bush's reinforcements cannot reach the front soon enough

The Pentagon signalled the most radical amendment to the strategic plan since the war started nine days ago, by announcing yesterday that an extra 100,000 troops would be sent to fight Iraq, in addition to the 30,000 from the 4th Infantry Division (Mechanised) already in the plan. They will join 250,000 Americans and 45,000 British in the Gulf.

In Washington, there have been rumours of a split among former US generals, including the Gulf War victors Colin Powell and Norman Schwarzkopf, who always thought more troops would be needed, and the Defence Secretary, Donald Rumsfeld, who hoped to move swiftly with fewer troops. If this is true, the generals were right. As soon as Iraqi resistance started proving tougher than expected, it was clear there might be a "density problem", not enough troops.

The extra US forces will come from Texas, Colorado and the garrison in Germany. They will increase the overall number by 50 per cent but will probably double the number of frontline combat troops in Iraq. The 4th Division will be ready to deploy probably within a week. The additional 100,000 and all their equipment will take longer to arrive.

They cannot get there too soon. The 3rd Infantry Division (Mechanised) is exhausted and potentially vulnerable at the end of a stretched supply line. The encirclement of Baghdad is expected to start in days. As General Sir Mike Jackson, the UK's Chief of the General Staff and its senior soldier, said yesterday: "The conventional fight with the Republican Guard may not be too far away."

So far, the US troops have tried to avoid fighting for towns, but they cannot do so indefinitely. If the Iraqi regime in Baghdad does not collapse, or is not overthrown by an internal rising or coup, US and British troops will have to go in and, if necessary, fight street by street.

Conventional military wisdom, which can be modified when one side enjoys overwhelming air, technological, and information superiority, is that the attacker needs a three-to-one local superiority in the open field. Studies suggest in cities the required superiority may be 10 or 12 to one. And hi-tech does not necessarily help. A pro-rata comparison with Northern Ireland suggests that if the Allies do have to move in to fight in the streets of Baghdad, up to 100,000 troops might be needed.

America, which has little experience of city fighting, has sought advice from the Israelis. But the Israeli tactical approach to urban warfare used on the West Bank and in the Gaza Strip hardly squares with the US and British politico-strategic war aim of "liberating" the Iraqis.

These debates present a striking analogy with the Anglo-American campaign in north-west Europe in 1944-45. The US commander, General Dwight Eisenhower, favoured a cautious advance out of France, through the Low Countries and into Germany on a "broad front", consolidating the country behind him as he went. The British commander, General Bernard Montgomery, rather uncharacteristically, had a more daring scheme. That is ironic, given Monty's reputation as a supremely cautious general. He favoured advancing as fast as possible on a narrow front. The latter came to grief on the "Bridge Too Far", at Arnhem.

In the present war, former US generals favoured an approach more akin to General Eisenhower's. The approach adopted so far, attributed to Mr Rumsfeld, is more like Monty's; move as fast as possible to grab decisive points and the centre of gravity, by-passing subsidiary objectives.

The arrival of US paras in the Kurdish-controlled area to open a second, northern front is also highly significant. The Americans will not be able to build up a heavy presence, but, given a couple of weeks and round-the-clock flights by massive C-17 transports, they should be able to put in a brigade with Bradley infantry fighting vehicles.

Armies who have no respect for the enemy often lose. The tabloid press has called the Iraqis "savages" and ministers have called elements of the Iraqi forces "thugs". The Iraqis are brave, tough, and doing a lot better than many people expected.

Their defensive strategy is clever. In the Western Desert in the Second World War the British faced a great German general, Erwin Rommel, the Desert Fox. The British beat him in the end, but they respected him. It is better to be frustrated by a knight than by a knave, after all. Perhaps the Iraqis have been reading Sun Tzu, again. "Offer the enemy a bait to lure him; feign disorder and strike him; pretend inferiority and encourage his arrogance." We should not be arrogant. We should respect the enemy.

Christopher Bellamy is professor of military science and doctrine at Cranfield University