Leading Article: A proxy war for the provinces of the south

The killing early yesterday of the governor of Iraq's Muthanna province offers the latest proof that, however bad the situation in Iraq might appear to be, it can, and probably will, deteriorate. Muhammed Ali al-Hasani, a Shia, is the second governor of a southern province to be assassinated in 10 days. Murthanna, moreover, was the first province to be transferred to Iraqi jurisdiction by the British military. This does not bode well, either for the eventual tidy withdrawal of the British contingent or for the Iraq they would leave behind.

It may be argued that there are special circumstances. Washington's much-publicised "surge" has brought calm to some former hotbeds of insurgency in central Iraq. Fallujah is one such trouble-spot that is experiencing some respite. Rather than stemming the violence, however, the "surge" seems increasingly to have displaced it - to the fringes of the Kurdish north and to the Shia south, both of which enjoyed relative peace before. The inescapable conclusion must be that even the present US troop level is too low to pacify all Iraq.

A second conclusion is equally inescapable: that no improvement can realistically be expected. While President Bush is reserving judgement about the "surge" until after his commander in Iraq, General David Petraeus, and the US ambassador in Baghdad, Ryan Crocker, have submitted their report in September, he has made pretty clear that upping the US troop strength is not an option. What is to be decided is rather how, and how fast, the US can reduce numbers and stem the casualties.

The implications are no more cheering for Britain's decision-makers. At Camp David last month, Gordon Brown set a small, but significant, distance between himself and Mr Bush on the matter of withdrawal, saying that he would defer to the judgement of his commanders on the ground. There was no talk - as there was during the Kosovo intervention, for instance - of British-US solidarity to the last. "We came in together, we will leave together," was the motto then. These are words that have not been heard for quite some time.

The difficulty for Mr Brown is that, if the security situation in the south is deteriorating as fast as it appears to be - in part because of the US "surge" - any delay in withdrawal will reduce the prospects that it can be done in good order and with dignity. The chief argument for remaining, at least in the short term, was that Britain had a responsibility to the Iraqis to hand over the region in a governable state. If the provinces already handed over are regressing into disorder, though, that hope looks unrealistic. At the same time, one argument for immediate withdrawal - that the foreign troops themselves constitute a destabilising factor and a target - seems less compelling than it was. The violence, even in the south, is developing a life of its own; it seems set to continue, whether British troops are there or not.

This combination of circumstances would seem to strengthen the argument for a British withdrawal, sooner rather than later. If, however, the upsurge of violence in the south reflects not just displacement occasioned by the US "surge", but a push by the Iranian-backed Mehdi army of Muqtada al-Sadr to fill the vacuum being left by the British, a complete withdrawal could speed Iran's emergence as the dominant regional power.

A British military spokesman said yesterday that increased violence had been expected as the planned handover of Basra neared. He was offering a riposte to Mr Sadr, who had claimed in an interview printed in yesterday's Independent that the British were retreating from Basra in defeat. There may well be an element of bravado in Mr Sadr's boast. But where power is at stake, perception is all and hope for peace seems to be fading.