Iraq's moment of truth as the weapons hunt gets under way

Mission an 'opportunity to avoid war'; US demands intrusive inspection

The decisive moment in the Iraq crisis has arrived. Today, UN weapons inspectors arrived in Baghdad for the first time in four years, on a mission that will either satisfy the world that Saddam Hussein has dismantled his weapons of mass destruction or else tip the Middle East into a devastating new war.

Hans Blix, the chief UN weapons inspector,landed in the Iraqi capital with a 25-member advance party to lay the groundwork for the full monitoring mission, which will begin its work on 27 November.

But even as he travelled from Vienna to Cyprus yesterday, and thence to Baghdad, he found himself buffeted by extraordinary new pressure from the US to impose the severest possible ground rules for the inspections and cry foul at even the tiniest of infractions.

Mr Blix stuck to the view that the UN mission was an opportunity to avert war, not an exercise in finding an excuse for one. "It's a chance for Iraq, and that's what the Security Council has said," he said, adding that war was not inevitable. "It's an important mission, but we've prepared ourselves for it. We know what we've got to do," he said. "The question of war and peace remains first of all in the hands of Iraq, then the Security Council and the members of the Security Council, but we have a very important role to play. We will report co-operation and lack of co-operation."

In the five days since President Saddam granted permission for the inspectors to return, the Bush administration has been unrelenting in its demands for a highly intrusive approach to the monitoring mission, including the right to take Iraqi scientists and their families out of the country for extensive debriefings.

Mr Blix has come under pressure to appoint a US official to oversee the flow of intelligence to the monitoring mission – a move that could be seen as jeopardising the UN's impartiality.

Washington has dismissed President Saddam's declaration that Iraq has already rid itself of weapons of mass destruction, suggesting that such statements are a sign of his inherent unreliability.

"We have heard such pledges before, and they have been, unfortunately, betrayed," President Bush said at the weekend in his regular radio address to the nation. "Our goal is not merely the return of inspectors to Iraq; our goal is the disarmament of Iraq. The dictator of Iraq will give up his weapons of mass destruction, or the United States will lead a coalition and disarm him."

The success of Mr Blix's team will rest largely on his ability to steer a delicate middle course between any intransigence on the Iraqi side and the Americans' apparent willingness to use even the smallest irregularity as an excuse to unleash a military invasion. A rhetorical gulf has opened in recent days between the US, with its demands for zero tolerance, and the UN, which has warned against adopting an "angry and aggressive" tone with the Iraqi leadership.

Kofi Annan, the UN secretary general, said last week the US appeared to have a lower threshold for military action than the other Security Council members, and cautioned against turning the inspections mission into a hunt for excuses to go to war.

On the American side, it is not entirely clear whether the unforgiving tone expresses a genuine eagerness to start hostilities, or is merely a device to keep up the pressure on President Saddam. There have been growing indications, including statements from President Bush himself, that the US might be willing to regard full disarmament of chemical, biological and nuclear weapons as an acceptable substitute for its stated goal of "regime change".