By Paul Reynolds BBC News Online world affairs correspondent

The endgame is now beginning and it is increasingly difficult to see how it can result in anything other than war.

The American position is quite clear - there will have to be a complete change of attitude by Iraq or it will be attacked.

The case against Iraq is now being made on two levels - the technical case that they have not co-operated with the inspectors and the larger case that Iraq poses a huge threat.

The weapons inspectors' first full report will be presented on Monday

Both US President George W Bush and UK Prime Minister Tony Blair are using the "Armageddon argument", saying that they must act in case international terrorists get weapons of mass destruction from Iraq.

There is not much which can rationally counter that. Critics can say that Saddam Hussein represents a completely different strand of Arab nationalism from Osama Bin Laden and that no links between them have been found.

But the spectre has been raised. And it is a major reason why war is so likely. Even the slightest doubt about Iraqi compliance will be used as evidence that they cannot be trusted.

The US Secretary of State, Colin Powell, said in Davos on Sunday that Iraq had "utterly failed" to co-operate with weapons inspectors.

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Where key nations stand on Iraq

His words matched those used by President Bush's National Security Adviser Condoleezza Rice on Friday. She said that Iraq was failing to co-operate with the UN "in spectacular fashion".

And both used the phrase: "Time is running out."

KEY DATES

27 Jan - First full report on inspections presented to UN 29 Jan - UN discusses report 31 Jan - Bush meets Blair 15 Feb - Anti-war protests across Europe 27 Mar - Blix submits new report to UN

Next steps in full

How much time is that? The best guess at the moment is about six weeks.

The United States and Britain have accepted that inspections will continue for the moment, but they can afford to be flexible.

Many of their big units needed for a war have not yet begun to move.

They cannot move quickly and they will not be in position until early to mid-March.

And the UN resolutions allow for inspections to go on anyway. There is no deadline for them to stop.

Tony Blair has said that inspections could continue for "weeks not months."

Half empty, half full

This important week starts with an open Security Council meeting on Monday at which the chief weapons inspectors give their update on the state of the inspections so far.

Already, Dr Hans Blix, the head of the UN weapons group Unmovic, has said publicly that his report will be a "mixed bag".

The Americans and British will seize on this to say that Iraq is failing in its obligations under Security Council Resolution 1441.

France, Russia, China and Germany and others will counter that there has been progress and that nothing yet justifies an attack.

For one side, the glass will be half empty, for the other, it will be half full.

Convincing the unconvinced

There will be another, closed, session of the council on Wednesday at which Dr Blix and his colleague Dr Mohamed ElBaradei, the head of the International Atomic Energy Agency (IAEA), might well be asked to report again in February.

British officials say that at this stage there will be no moves by the US or UK to introduce a second resolution authorising war. That will come later.

Mr Blair said on Sunday that "of course we want a second resolution".

Ideally, from the British and American point of view, the inspectors will conclude at some point that Iraqi co-operation is not sufficient.

Trying to convince an unconvinced world that action is needed is going to be a large part of the US and UK's task

This will then give the US and UK governments a platform on which to build support for a war resolution.

If the inspectors do so conclude, then the argument of the French, Russians and Germans that the process should be extended for months if necessary will be strengthened.

President Bush's attitude will be evident in the annual State of the Union speech to Congress on Tuesday.

He will undoubtedly rattle his sabre but is not expected to draw it yet.

And on Friday, Mr Bush will hold talks at Camp David in the US with Tony Blair about their strategy.

Trying to convince an unconvinced world that action is needed is going to be a large part of their task.