American and Iraqi leaders are finalising a security pact that promises to bring the curtain down on the US occupation. Although some details have yet to be worked out, the Bush administration has bowed to Iraqi pressure for a troop withdrawal timetable.

Iraqi officials are claiming the so-called status of forces agreement will remove US combat troops from Iraqi cities by June and from the rest of the country by the end of 2011. The US calls these dates “aspirational goals” that will depend on the security situation. Still, only a month ago the Bush administration was furiously opposed to a time­table, insisting it would reflect an admission of defeat and play into the hands of its enemies.

Faced with a surge of Iraqi nationalism, however, it has agreed to a plan that looks embarrassingly closer to the position of Barack Obama, the Democratic presidential candidate, than to the 2013 withdrawal date supported by John McCain, his Republican rival. Despite the progress, the agreement may not be signed before a new US president takes office, although the UN mandate that regulates the foreign military presence in Iraq expires at the end of the year. The deal has to be officially approved by Iraq’s presidential council, and it will need the stamp of a fractious parliament that has failed to settle far less contentious issues.

But if it is to be a blueprint for Iraqi stability – and an accord around which Iraq’s quarrelling political factions coalesce – the agreement must commit the US not to maintain permanent bases in Iraq. It must also find a compromise over the hypersensitive US demand for legal immunity for its forces.

Given Iraq’s fragile state, it is far from clear that the agreement will stick and deadlines will be met. A convergence of events over the past year – the “surge” of US troops, the enlisting of former Sunni insurgents against al-Qaeda and Shia leader Moqtada al-Sadr’s self-imposed ceasefire – has produced a considerable reduction in violence. But even the US military acknowledges that improvements are reversible.

Indeed, the US-backed Sunni militias are growing increasingly frustrated: not only has the government been slow to integrate them into the security apparatus but now it seems to be cracking down on them. Even more dangerous is the struggle over the oil-rich city of Kirkuk, which the Kurdish minority is determined to join to its autonomous northern region. The US presidential election has helped concentrate minds in Washington on withdrawal from Iraq – but an orderly exit is still far from guaranteed.