I agree with Metatone that it would be irresponsible for an occupier to just leave because they feel the occupation is bothersome and costy for them. "Let Iraqis sort it out amongst themselves" is a cruel joke for the average Iraqi, who is not part of one of the armed groups whose strength is in RPGs and threats not votes (and, if you study the January 'elections' deeper, even the votes had more to do with the former than voter's wishes). However, I don't think you can make a case for the occupiers in Iraq having any positive influence (I just started another diary touching that subject) - Iraq's state and future is terrible, it's our fault, but you can only make it worse.

This is where in part I disagree with Oui: even Southern Iraq is not a success story, as spun by European participants of the occupation. Especially the British sector: there, the situation is basically that Western troops are in barracks, while various Shi'a militias (not just Muqtada al-Sadr's Mahdi Army: also the troops of the rival Sadrists of the Fadila party, the SCIRI-allied Badr brigades, the Daawa party militia, and the Marsh Arab Hezbollah) rule the streets. And even the little local contact that exists was a source of a lot of trouble, with Britain's own scandals of prisoner abuse and killings - no wonder there have been IED attacks against the British too, especially around Amarah. Meanwhile, in Najaf, when there were lots of stories about the Mahdi Army takeover, the press forgot to mention whom they took over from - for there was a previous takeover by the Badr Brigades, just after the US invasion.

Regarding Metadone's potential bad consequences of withdrawal, the point is that you can't prevent these to happen. The situation is that bad.  

Not with a phased withdrawal, not with UN troops that aren't any more asked for by Iraqis, nor are possible in sufficient numbers (=a million by now) even just to stop violence. Worse: the current US policies in fighting the guerillas, and the likely policies connected with a phased withdrawal, actually enhance these trends. The forces of separatism, i.e. the two large Kurdish warlords with their peshmerga, were made stronger not weaker, both by the pseudo-democratic process and the US's reliance on peshmerga fighters in its war with the guerillas. US plans for a 'Salvador Option', which seems an integral part of any staged withdrawal, would make this worse. The type of 'reconstruction' caused the implosion of local economy. Iranian influence got enthroned by way of inclusion of SCIRI and Daawa in first the Iraqi Government Council, then the shambolic election process (Sistani's all-Shi'a party with its pre-set quotas and all preachers and most militias as its campaigners had little to do with democratic choice). These things now have their own dynamic, and you'd have to act like an absolutist dictator to stop it - whether you're the US or UN.

BTW, I don't think an Iranian annexation of southern areas is even a remote possibility. Iraqi Shi'a are Arabs (which would be a problem for the Persian leaders of an already multi-ethnic country too), and in large part nationalist, remembering the Iraq-Iran war. What is more likely is a breakaway client state.

_{*Lunatic*, n.
One whose delusions are out of fashion.}