The dynamic has shifted dramatically in Iraq since Gen. David Petraeus, who handed over command in a ceremony presided over by Defense Secretary Robert Gates, became the senior officer here in February 2007. Iraq was mired in sectarian civil war then and in his first month on the job, 2,864 Iraqis died as a result, and there were an average of 180 attacks against coalition forces every day.
To be sure, Iraq is still very much at war. But last month hundreds of civilians were killed instead of thousands, and in June fewer than 20 attacks a day targeted coalition troops.
General Odierno will be charged with not only maintaining these successes, but building on them. He will be faced with mediating growing tension between America's Sunni allies and Iraq's Shiite government. He will monitor cease-fires and moderate post-conflict issues. And, perhaps most significantly, he will have to navigate the political climate in Washington as a new administration takes office.
"The big change that Odierno is going to need to come to grips with is, 'OK, Petraeus and I, we refashioned the force to do basically low-intensity conflict … now we've got to transition over toward a series of more like peacekeeping operations,' " says Kenneth Pollack, director of research at the Brookings Institution Saban Center for Middle East Policy in Washington.
For his part, Odierno, who describes himself philosophically "very close" to General Petraeus, acknowledges that the challenges and issues ahead will be different from those he encountered during previous tours of duty.
"Today Iraq is a different country from the one I encountered in 2004," he told attendees at the change of command ceremony. He later told reporters, "We're in a fragile state, but I want to build it into a stable state."
The problems facing Odierno include the more than 4 million war refugees and dealing with the community policing organization known as the Sons of Iraq (SOI), says Dr. Pollack. If refugees cannot find homes and the SOI isn't properly monitored, they may create security issues for Iraq once again.
The SOI began as part of the Anbar Awakening, the movement of anti-Al Qaeda Sunni sheikhs who turned against extremist elements in Anbar Province and played a role, along with the "surge" of troops and the cease-fire ordered by radical Shiite cleric Moqtada al-Sadr, in lowering violence in Iraq. However, ex-insurgents joined the US-funded corps seemingly for financial reasons. And when the US stops paying their salaries in October, many here worry they will simply be lured back into the insurgency.
But Odierno is now working with Iraqi security forces, which include police and all branches of the military, that are increasingly able to take on militants. A bigger Iraqi military "will compensate for the number of troops we're losing from the coalition," says Gen. Nasier Abdi, vice chief of the Iraqi Army. Consequently, he says that Odierno will have to manage a shift to a larger advising role for US forces.
Although Petraeus leaves his position commander of US forces in Iraq, he will maintain an active role in the county in his new job as head of the US Central Command, which oversees US military operations in the Middle East, East Africa, and Central Asia.
"The main uncertainties at this point are probably in Washington rather than in Iraq," says James Dobbins, director of the International Security and Defense Policy Center at the RAND Corporation, a US think tank.
No major changes are anticipated in Iraqi political leadership. Even US Ambassador Ryan Crocker is expected to remain in office for at least the first several months after the next president takes office.
The US political future, however, is much more amorphous, says Mr. Dobbins. "In Washington you'll have a new administration with new priorities, a growing demand for troops in Afghanistan, and a diminished appetite for the war in Iraq."
Winning the confidence of a new US president, he says, will probably be one of Odierno's biggest challenges.
The new command position marks Odierno's third tour in Iraq. On his first, he commanded the 4th Infantry Division (4ID) in the initial invasion of Iraqi in 2003. A number of analysts, notably the author of "Fiasco," Washington Post reporter Thomas Ricks, have criticized the 4ID under Odierno for using harsh tactics. Odierno, however, rejects this characterization, saying that the situation still called for an aggressive posture.
During his second tour he worked as Petraeus's deputy commander responsible for operational planning. He worked with Petraeus to improve the US military's counterinsurgency strategy and better relations with Iraqis.