Sunday's handover of Basra province, the last of four controlled by UK forces since the 2003 invasion, was heralded by the British and Iraqi governments as a great step forward. Local forces were now capable of looking after the security of the entire south-east of their country, potentially one of the Middle East's richest regions.In truth, the decision was dictated by British domestic politics and by the demands of British military commanders. Britain's continuing presence in Iraq was becoming increasingly unpopular and counterproductive. More than a year ago, General Sir Richard Dannatt, newly appointed head of the army, said that Britain should withdraw from Iraq "soon" because its troops were regarded with growing hostility, with their presence exacerbating the difficulties Britain was experiencing around the world. It has also mounted the pressure on the army when it is engaged in increasingly intense fighting in Afghanistan.
So why the delay, and why now? Britain had to convince the US that a reduction in the number of British soldiers in southern Iraq, and ending their counter-insurgency combat role on the streets of Basra, was essential, politically and practically. And for months, if not years, British army commanders have been decrying what they called the Iraqi "dependency culture". Setting a timescale for handing over responsibility for security in Basra province "concentrated people's minds in Iraq", as one senior Foreign Office official put it. Baghdad sent two heavy hitters - Generals Mohan al-Furayji and Jalil Khalaf - to command the Iraqi army and police forces in Basra.
Britain claimed that it had trained enough Iraqi security personnel - most of the 30,000 in total in Basra - to create capable autonomous forces. The credibility of the claim has yet to be seriously tested.
Senior military officials, including Air Chief Marshal Sir Jock Stirrup, chief of the defence staff, admit that expectations about what they could achieve in southern Iraq were exaggerated. "Our mission was not to make the place look somewhere green and peaceful," he said in the summer. He was speaking at the time troops were preparing to leave the Basra Palace, their last remaining base in the city, and one they would have left much earlier - saving more than 25 British soldiers's lives - had it not been for US pressure and the apparent judgment then that Iraqi forces were not ready.
Yet despite Sunday's handover, 4,500 British troops will still be based at Basra airport and the 2,500 which Gordon Brown says will be there in the spring are likely to remain at least until 2009, partly at the behest of the US.
What can they achieve? Further training and mentoring of Iraqi forces, the government says. They would also step in and help in the event of a crisis - something British military commanders and ministers desperately hope won't happen. What have they achieved? When they entered Basra in 2003, they handed out sweets and water and helped to clean the streets. Now they can't safely enter the town even in armoured vehicles. Iraqi security chiefs and politicians say the British should go and that when they do security will improve significantly. Yet police chief Khalaf told the Guardian yesterday that Britain had left him to cope with militia, gangsters, and beheadings of women considered insufficiently Islamic.
This week could prove a turning point in Basra, with British troops allowed to twiddle their thumbs while the Iraqis maintain law and order (for the first time since Saddam was toppled) and UK aid money reaping rewards from such an oil-rich, strategically important region. Or it could prove to be a humiliating and empty end to a four-year occupation.
Richard Norton-Taylor, the Guardian's security affairs editor.