Bush-Blair meeting:
UK Prime Minister Tony Blair is due to meet President George W Bush on 31 January to discuss the Iraq crisis.
Both leaders have said that they do not believe Iraq has any intention of disarming in accordance with Security Council resolution 1441 and that they are prepared to launch a military campaign to ensure Iraq does so with or without UN backing.
Key dates
Adopted on 8 November, resolution 1441 is designed to force Iraq to give up all suspected weapons of mass destruction.
But at any point, the inspectors can decide that their work is being obstructed and make a report to that effect.
Washington and London have already invoked the phrase that could trigger a war, accusing Iraq of being in "material breach" of resolution 1441 in a document detailing what weapons programmes it says it has.
It had been thought that the US and UK would go back to the Security Council to seek authorisation for military action.
This is looking more and more unlikely because France - a permanent member of the Security Council - and Germany - currently on the council - have said they are determined to prevent war in Iraq and that they will work together to achieve this.
US to call Security Council meeting:
In his State of the Union address on 28 January President George W Bush promised to reveal fresh evidence about Iraq's weapons programmes.
The US is planning to ask the UN Security Council to hold a special session on 5 February at which Secretary of State Colin Powell will present this evidence.
Further inspectors' report:
The UN weapons inspectors are expected to deliver another assessment of Iraqi co-operation to the Security Council on 14 February.
Military timing:
The US has been assembling forces for possible military action in the region.
Military analysts say the expected deployment of 150,000 personnel in and around the Gulf by the second half of February would be enough to launch what the Pentagon calls a rolling start attack, with more reinforcements arriving rapidly after that.
Other analysts say the types of troop deployments announced by the US and UK indicate that a ground war could be launched from about the middle of March.
It is also possible that an air campaign might be launched in advance of the arrival of the full contingent of allied forces.
Washington will have to take into account that a delay beyond the end of January or early February in any decision to go to war would see conditions for allied troops fighting in Iraq begin to become dangerously hot as winter ends and summer approaches.
Temperatures in the Iraqi desert will begin to heat up by March. In July and August, the average temperature is more than 48 C (120 F).
Troops will have to be dressed in chemical protection gear the whole time, which will become extremely hot.
Also, April marks the beginning of Iraq's windy season, when sandstorms could severely reduce air operations.
The weather would not cool down again until October.
However, senior officials have warned that the hot weather does not necessarily mean that a military campaign will be put off - it just makes it that much more difficult.
According to reports in the Washington Post newspaper, the Bush administration has set the last week in January as the point when it decides whether or not there is enough evidence to warrant a war against Iraq.
Key dates so far: