BAGHDAD, Iraq (CNN) -- Gen. Ray Odierno on Tuesday took command of U.S. forces in Iraq, marking the end to Gen. David Petraeus' tenure, which saw a reversal in the country's rising violence.
"It's a proud moment for me to be given the responsibility to take command of Multi-National Force-Iraq and continue the mission here in Iraq as we move forward," Odierno said in Tuesday's handover ceremony in Baghdad.
"As we've said many times, everyone is encouraged by the progress that has been made here in Iraq, but we still have a lot of work to do," Odierno said at the ceremony attended by U.S. Defense Secretary Robert Gates, who handed Odierno the Multi-National Force-Iraq flag.
"We are in a fragile state now. What I want to do is build it to a more stable state. And I think we're in the process of doing it. It just takes some time, and it's slow." Watch what challenges Odierno faces »
Odierno said he is "encouraged" by the growth of Iraqi security forces and the national police.
"We're starting to see signs of some other of the governmental capacities begin to grow, which I think is extremely important," he said. Watch highlights of the change of command ceremony »
Petraeus took over in February 2007, a month in which six U.S. helicopters were shot down, deadly bombings were common and nearly 500 bodies turned up in the capital.
Since then, the "surge" has become a buzzword in American politics. The temporary influx of 31,000 U.S. troops is credited, in part, with reducing violence across Iraq.
"I think that Gen. Petraeus will be regarded by history, by military historians, as a great American military strategist," said Martin Navias, defense analyst for the Center of Strategic Studies at Kings College in London. "When he came into power ... the situation in Iraq was terrible. He supported a surge."
Sectarian violence is down, according to the U.S. military, from 60 incidents a week to what it now calls "negligible levels."
U.S. troop deaths are down as well.
In 2007, 906 American troops died in Iraq, the deadliest year of the war. Through Monday, nearly nine months into the year, the U.S. death toll was 248.
Petraeus says the future of Iraq is still uncertain.
"There are many of these possible storm clouds that are out there," he told CNN. "So Ray Odierno and the CENTCOM future command will still have lots of rocks in our rucksack."
CENTCOM is the U.S. Central Command, the military command responsible for a region of the world that includes Iraq. Petraeus' next assignment is commander of Central Command
Refugees, internal Iraqi politics and the restoration of basic civil services are just a few of the issues Odierno will have to deal with as the commander of U.S. forces in Iraq.
Odierno's strategy is expected to pick up where Petraeus' left off.
U.S. troops have spread out across the country, tracking insurgents as they've fled the population centers.
The U.S. military is working with former Sunni insurgents in groups known as "awakening councils." The groups are getting much of the credit for keeping violence down.
• A marketplace bombing Tuesday morning killed two people and wounded 13 others, an Iraqi Interior Ministry official said. The blast took place in Taji, about 12 miles (20 kilometers) north of the capital. The bomb was carried on a bicycle, according to residents.
• A roadside bomb, apparently aimed at a police convoy on an eastern Baghdad street, killed at least one Iraqi police officer and wounded seven others Tuesday, according to an Interior Ministry official. Four of the wounded were police and the three others were civilians, the official said.
CNN's Cal Perry contributed to this report.