Challenges in an exit strategy

As of September 1,the 50,000 troops who remain will be part of six brigades organised as trainersa much thinner force than the 140,000 there when Obama took office.

These troops could still be sent into combat,depending on what happens around them. For the American forces,that seems to indicate a period of uncertainty. What would happen if,for example,Iraqs political crisis flares into violence? What if al Qaeda in Iraq regains control of neighbourhoods or villages? What do American troops do if Iraqs security forces launch a coup?

The outgoing American commander in Iraq,Gen Ray Odierno,has built some flexibility for responding into the military structure he will hand off to his successor,Gen Lloyd J. Austin III,on September 1.

Along the volatile line that separates Iraqi Arabs and Iraqi Kurds in northern Iraq,for example,he is leaving in place a combat brigades headquartersthe commanding officers,that is,without the combat troops themselves. They will remain in Kirkuk,a city claimed by both sides. Should violence necessitate it,the headquarters could easily assume command of a training brigade and send it on a combat mission.

In a war where language has been a battleground as much as Iraq itself,there are two realities behind such calculations. One is that the conflict in which American troops are still enmeshed remains ominously unresolved among the Iraqis themselves. The other is that violence is considerably lower than it once was,and Iraqi forces seem more capable of dealing with it on their own.

My sense is the military sees the terms of the advise-and-assist role as sufficiently broad to do whatever the US command authority and the Iraqi command authority want to do,including combat, said Ryan C. Crocker,the former ambassador in Baghdad.

In one sense,Obama was simply reaffirming a transition he initiated last year,and the name of the mission in Iraq is only now catching up to the way American forces have actually been operating for some time now. Training brigades have been in Iraq for months; the last few thousand troops formally assigned as combat units are to leave by September 1.

Meanwhile,Iraqs security forcesthough still weak,suffering from uncertain professionalism and outright corruptionhave largely taken over responsibility for day-to-day security,leaving the six Army brigades to train and assist,when asked. Increasingly,the Americans arent being asked.

The trainer troops left in Iraq will continue to carry weapons and fire them when threatened. American airpower will still conduct surveillance and drop bombs or fire rockets if Iraqi forces find themselves pinned down. Special-forces units will still carry out raids in search of insurgents,as they do in places like Pakistanwith as little publicity,they hope,as possible.

And American blood,as the president noted,will still be shed on foreign soil.

Ultimately,Obamas August 31 deadline for ending combat operations is a self-imposed political one,a fulfillment of his campaign pledges to withdraw from a deeply unpopular war. It was never a legally binding one.

So on September 1,when Operation Iraqi Freedom officially becomes Operation New Dawn,the Americans will be based near the most important cities,from Basra to Baghdad to Mosul. And they will be available to intervene until the end of 2011.

Lt Col Gregory F. Sierra,a battalion commander with the Armys Third Infantry Division,recently compared the evolution of the American war effort to spreading peanut butter on the sandwiches he makes for his daughter back home more thinly than she wanted.

Then,mindful that his image might suggest that the remaining force was somehow less than potent,he revised it. Chunky peanut butter, he said.