The Iraqi parliament delayed a vote until today on the security agreement between the US and Iraq which will see American forces leave Iraqi cities, towns and villages by next summer and Iraq as a whole by the end of 2011.

The delay came because the Shia-Kurdish government is trying to win Sunni Arab support for the pact in return for concessions. The government has agreed there should be a national agreement on the Status of Forces Agreement with the US to be held next year and which could, in theory, rescind the accord if Iraqis voted against it. The concession may allow Sunni lawmakers to vote for the agreement but claim the decision will be made by the whole Iraqi people.

The Sunni Arabs, 20 per cent of the population, fear that as the Americans depart, the chiefly Shia government of Nouri al-Maliki will be more powerful. They want to make demands now, such as an end to the prosecution of former Baath party members, the release of Sunni prisoners and to secure the safety of 17,000 prisoners held by the US.

The security agreement will shape Iraq's political landscape. The accord has an unconditional time limit on the withdrawal of US forces. The US will need to co-ordinate operations and arrests with Iraqi forces and hand over the Green Zone.