Rumsfeld shows the strain as experts query his strategy

The strain is starting to show even on Donald Rumsfeld, the formidable and remarkably well-preserved 70-year-old Secretary of Defence who is running the campaign in Iraq. "How does anyone outside government know what my views are?" he positively snarled the other day at a questioner who had the temerity to wonder whether the smaller, faster sort of war he advocated might be a mistake.

Outwardly, it's the usual pugnacious Rumsfeld, the steamrollering CEO who brooks no dissent. But look more closely and the lines of strain are visible. The tiredness is evident in the eyes, and little wonder. For he is the man in the hot seat as, eight days into the Gulf War of 2003, a once cocksure America is forced to face the possibility that it may be months, not weeks, before a war sold as a virtual cakewalk is over.

"Saddam has learnt from Gulf War One, and he's learnt from Mogadishu," Kenneth Pollack, an Iraq specialist at the Brookings Institution, said yesterday, referring to the unhappy US military intervention in Somalia in 1993, which ended after dead American soldiers were dragged through the streets of Mogadishu. "He's learnt that irregulars and paramilitaries can cause problems, using things like human shields. Maybe he watched the movie Black Hawk Down over again," Mr Pollack said, adding, "I'm only half-facetious."

And behind the daily recitations that "everything is going to plan", Pentagon officials grudgingly admit that the resistance has been stronger and more tenacious than expected.

Sources in Washington said last night America intended to double its frontline fighting force in the Gulf from 100,000 soldiers and marines to about 200,000 in the next month. They insisted, however, that was part of a planned build-up.

Admittedly, "friendly fire" apart, US and British casualties have been minimal. But the guerrilla hit-and-run tactics, with the blinding sandstorms of the past two days, have slowed the advance. Supply lines strung out for 250 miles on jammed, inadequate highways have been stretched to breaking point. This week, the US 3rd Infantry Division leading the thrust to Baghdad virtually ground to a halt, short of fuel and even food and water. Exhaustion is also forcing a pause in which to regroup, rearm and resupply.

All of this raises a deeper question. Did Washington, seduced by the dream of a speedy and easy victory, put too few troops in the field?

No, say the architects of the strategy. "Our plan is brilliant," General Richard Myers, chairman of the Joint Chiefs of Staff, proclaimed as the first doubts began to stir. "We're on track, we're on plan. We think we have just the right forces for what we need to do now."

Other military experts beg to differ. They point out that the 250,000 military personnel deployed in and around Iraq make up a force only half the size of that assembled for the 1991 Gulf War, which was fought moreover in flat, desert conditions ideal for US armour.

The heavy forces in the field – the 3rd Infantry, the 1st Marine Expeditionary Force and the 101st Airborne (not yet fully deployed in Iraq) plus the British are not enough, they say – even given total Allied control of the air. "We needed at least four divisions and the British. We've got three and the British, and we're getting a harder war than expected," Mr Pollack said.

Of the above elements, only the 3rd Infantry is a really heavy fighting force with tanks and armoured vehicles. Additionally, the withering fire put up by Republican Guard units blunts the effectiveness of the deadliest US battlefield weapon, the Apache attack helicopter. But the deficiency should be made up with the belated arrival of the 4th Infantry Division, which was supposed to have launched a second front from the north towards Tikrit, President Saddam's family stronghold, and Baghdad itself.

That plan perished when Turkey refused to allow US ground troops to use its bases. The 1,000 paratroops landing in Kurdish-controlled Iraq yesterday morning are scant substitute for the 62,000 men the Pentagon wanted to mass along the Turkish border.

Now the 4th Infantry and its 30,000 troops are being deployed from Fort Hood, Texas, to Kuwait, whence they will move north to reinforce the American force gathering to launch the decisive assault on Baghdad. The armada of ships carrying their armour has started to arrive in the Gulf from the eastern Mediterranean. The 4th Infantry should be combat-ready by early next month, at which point it will move north to the front, allowing secondary forces to be released to guard supply lines. All of which is reasonable enough – except that it wasn't in the original script.

More than any other conflict in history, this media-saturated war, with its unprecedented real-time coverage from the battlefront, has been a prisoner of expectations.

The optimism at the outset was excessive, fuelled by the likes of Dick Cheney, the Vice-President, who – three days before the war started – predicted on national television that the Republican Guard would do what General Myers yesterday called "the honourable thing", and not fight at all. Until early this week, the mighty array of pundits and military specialists did not mention the word "Fedayeen".

Now the pendulum has swung back. The war, it is said, will last for months (raising the intriguing prospect of the US and Britain still slugging it out in Iraq when Messrs Bush and Blair meet the "peace trio" of Jacques Chirac, Vladimir Putin and Gerhard Schröder at the G8 summit in France in June). "Tell me how this ends?" a gloomy senior US officer was quoted as saying in The Washington Post.

Mr Blair was surely correct when he insisted at his war council with the President at Camp David yesterday that "an enormous amount" had been achieved. "We've disabled Iraq's ability to launch an attack [against Israel] from the west," he said. "Our forces are within 50 miles of Baghdad, they've surrounded Basra, they've paved the way for humanitarian aid, and inflicted real damage on the Iraqi government's command and control."

But neither leader would commit to a timetable. On Capitol Hill yesterday, Mr Rumsfeld warned that the Republican Guard was likely to defend the regime to the end. "We must expect that it will require the coalition forces moving through, destroying Republican Guard units around Baghdad, before you see the crumbling of the regime," he said.

The question is, will that take weeks, or months?