Iraqi Prime Minister Nouri al-Maliki (AP Photo)

Four years ago Sunday, President George W. Bush summed up U.S. military strategy in Iraq for an audience at Fort Bragg, N.C.: “As the Iraqis stand up, we will stand down.”

It finally has happened. Today the Iraqis are observing “National Sovereignty Day,” a holiday decreed by Prime Minister Nouri al-Maliki to celebrate the withdrawal — or, as Mr. Maliki put it last week, the “repulse” — of U.S. forces from its cities, towns and villages.

Most of the 131,000 U.S. forces remaining in Iraq have been withdrawn to forward operating bases and massive camps in the countryside. All of them are to leave the country by the end of 2011. Mr. Bush agreed to these deadlines before leaving office and turning the mess he created over to President Barack Obama.

So this is how the Iraq war ends — not with a majestic surrender ceremony aboard the Battleship Missouri and not with people hanging from helicopter skids over the embassy in Saigon — but with the orderly transition of managing civil disorder. The job now belongs to Iraqi security forces and U.S. advisers who can order up airpower and infantry backup, but only when asked.

“I do believe they’re ready,” General Ray Odierno, the U.S. commander in Iraq, said on CNN Sunday. “They’ve been working towards this a long time.”

Mr. Maliki’s use of the word “repulse,” made in an interview last week with the French newspaper Le Monde, surely will grate on American ears. It suits Mr. Maliki’s domestic political purposes to talk tough about American troops as occupiers and meddlers, though he surely owes his own ascendancy and perhaps his very life to the American presence.

Some 4,316 American troops have died to put him and keep him where he is. More than 31,000 were wounded, many grievously. Several hundred thousand more suffer the effects of post traumatic stress disorder or traumatic brain injury. The United States has spent nearly $700 billion on this war, and that’s direct costs alone. The longterm cost could exceed $2 trillion, some economists estimate.

So now we have been “repulsed.” The word offers a clue to what comes next.

Under the best possible scenario, Iraqi security forces will be able to contain the violence that still wracks the country without an egregious crackdown on religious and ethnic minorities. Parliamentary elections scheduled for January will be open and free. Democracy will flower, as Mr. Bush and his neocon supporters dreamed it would in 2002.

But a dozen Iraqis a day still die from suicide bombings or executions. That’s down from six or seven dozen a day a few years ago, but a lot of work remains. The U.S. troop surge and counterinsurgency tactics of 2007 brought relative calm to the streets, but did little to foster a workable, open system of government.

In addition to sectarian violence — insurgent attacks and reprisals from the Shiite-dominated government on Sunni minorities or Kurdish nationalists — Iraq now suffers from intra-sectarian factional violence. This is something new for Iraq — gang violence without a religious cloak.

The more likely scenario is that these various factions and insurgencies will use the withdrawal of U.S. forces as an occasion to crank up the violence, causing a hard right government backlash and open revolt in Kurdish northern Iraq. The United States could find that being halfway out of Iraq is harder than being all the way in.