On Tuesday, the withdrawal of US forces from Iraq's cities was more or less complete – a sign that, six years after the troops arrived, Iraq is much safer than at the height of its sectarian violence a few years ago.
Now, both US and Iraqi commanders say they expect an increase in attacks as insurgents test the new security arrangements in the coming weeks, which raises the question: Is there a threshold of violence beyond which US troops would return?
"You are going to see, as we withdraw, a lot more fighting and violence between Sunni and Shiites," says Col. Pat Lang, former head of the Middle East desk at the Pentagon's Defense Intelligence Agency. "But it would take a lot – a lot – for [President] Obama to be willing to fully reengage, and [Prime Minister Nouri] Maliki isn't really going to want him to anyway. We have to accept the idea that it's over, really; Maliki said it's over, really, and our timetable, out by the end of 2011, is the one we're going to follow."
How US role will be different
"Our incomplete sovereignty and the presence of foreign troops is the most serious legacy" from Saddam Hussein, said Mr. Maliki in a national address to mark "Sovereignty Day" on Tuesday. Later in the day, he said that "the national unity government succeeded." Conspicuously absent was acknowledgement, grateful or otherwise, of the American military's role.
Under the terms of the Status of Forces Agreement (SOFA) the United States signed with Iraq last year, US soldiers will need Iraqi permission to conduct combat patrols and other activities in the cities. Most analysts expect such permissions will be granted when needed.
US commanders said they will stay particularly active in providing attack helicopters and other aerial support to Iraqi forces in the coming months.
Convoys delivering food, ammunition, and fuel to US bases will still be vulnerable to roadside bombs, and major US installations – like the 100-acre embassy compound on the west bank of the Tigris River – could be attacked by mortars or other forms of indirect fire.
Key challenge: Former Sunni jihadis recruited by U.S.
Attacks on US interests in Iraq, and consequent US casualties, are likely to remain a challenge until Sunni Arabs, upset at what they see as the dominance of Maliki's Shiite coalition over the state and the distribution of its resources, cease their low-level insurgency. But some analysts warn that the biggest threat to Iraq's stability will be a failure to integrate some of the Sunni fighters that once fought the Americans and the Iraqi government.
Known as the Awakening Council or Sons of Iraq, these former jihadis were recruited and paid by the US as part of Gen. David Petraeus's counterinsurgency strategy, which has been credited for slashing the number of daily attacks from 170 in June 2007 to below 20 today, according to a report by the US government's General Accounting Office.
Colonel Lang says that if the government stops making payments to the Sons of Iraq – as some Shiite politicians have been urging – or otherwise takes action that leads to further alienation, a return to full-scale sectarian warfare can't be ruled out.
"It isn't so much a question of them taking up arms against the government at first," he says, "so much as they might stop helping, as they've been informing on and chasing around the [Sunni rejectionists] and so forth. But if goes far enough, they will start fighting the government again."
In remarks after he met with Egyptian President Hosni Mubarak this week, General Petraeus acknowledged that much progress on political reconciliation inside the country has yet to be made.
"There are many, many difficult political issues, social issues, governmental development issues," he said, adding, "We feel confident in the Iraqi military forces continuing the process of taking over the security tasks in their own country."
'Patchwork quilt of former rivals'
The numerous Sunni contingents that came together under the Sons of Iraq were among more than 200 separate armed groups with whom the US made arrangements that led to Iraq's relative calm, according to a report on Iraq released in late May. Other groups included Shiite militias, such as the one aligned with militant cleric Moqtada al-Sadr.
"The result is a patchwork quilt in which former rivals, who retain their weapons, their organizations, and often their leaders, coexist uneasily in close proximity under the terms of deals reached with local US military authorities over the course of 2007," wrote author Stephen Biddle, a senior fellow for defense policy at the Council on Foreign Relations. "Parties to intense ethno-sectarian warfare do not just forget the mass violence of the past overnight ... some will surely stretch the terms of their agreements to see what they can get away with."