Odierno takes over as U.S. commander in Iraq

BAGHDAD (Reuters) - General Ray Odierno took command of U.S.-led forces in Iraq on Tuesday, faced with the challenge of ensuring security gains do not unravel at a time when American troop levels are being reduced.

Odierno replaced General David Petraeus at a ceremony presided over by U.S. Defense Secretary Robert Gates, who said the two generals had formed an "incredible team" during the deployment of 30,000 extra U.S. troops to Iraq last year.

The towering, shaven-headed Odierno served as the number 2 U.S. commander in Iraq for 15 months until February.

"He (Odierno) knows that we are at a pivotal moment -- where progress remains fragile and caution should be the order of the day," Gates said in the ornate halls of one of Saddam Hussein's former palaces that is now part of a giant U.S. military base.

Odierno reinforced that message, saying that while Iraq was a different country from two years ago -- when it was on the brink of civil war -- improvements in security were reversible.

The Pentagon will pull 8,000 troops out of Iraq by February, leaving 138,000 soldiers deployed there. All five extra combat brigades sent to Iraq last year completed their withdrawal in July and have not been replaced.

Despite the drop in overall violence in Iraq to four-year lows, the Bush administration has taken a cautious approach to troop cuts and any decision on a major withdrawal will be left to the next U.S. president, who takes office in January.

The Iraqi government wants U.S. troops to withdraw by the end of 2011 under a security deal being negotiated with Washington. Asked if he thought Iraqi forces would be ready to handle security by then, Odierno told reporters:

"We'll see what the agreement says but ... 2011 is the date we're looking towards. I think it has to do with the capacity we're able to build ... I'm cautious in making any judgments at this time."

Odierno added that a key challenge was making sure militant groups could not bounce back.

A female suicide bomber killed 22 people at a dinner celebration for police in Diyala province on Monday, hours after two car bombs killed 12 people in the capital Baghdad.

"FEARSOME BEATING"

Odierno and Petraeus came together last year to implement a new counter-insurgency strategy that helped drive violence down, allowing Iraq to begin seeking foreign investment to rebuild after decades of war and U.N. sanctions.

"Slowly, but inexorably, the tide began to turn. Our enemies took a fearsome beating they will not soon forget," said Gates.

Odierno will face other challenges.

Iraq's Shi'ite-led government will soon take control of Sunni Arab tribal units that joined forces with the U.S. military to fight al Qaeda. Some analysts fear the tribal units, which include many former Sunni Arab insurgents, could turn their guns on the government if their demands are not met.

Odierno also stressed the importance of Iraq holding provincial elections, which U.S. officials hope will cement national reconciliation by giving groups that boycotted the last local polls in 2005 a voice in regional affairs.

The elections were to have been held next month, but have been delayed by bickering between Kurds and Arabs in parliament over an electoral law.

Gates lauded Petraeus in his speech at the ceremony.

"You ... dealt the enemies of the United States and Iraq a tremendous, if not mortal, blow. History will regard you as one of our nation's great battle captains," Gates said.

From October, Petraeus will head the U.S. Central Command, the headquarters overseeing operations in the Middle East and beyond, including the war in Afghanistan.

Officials and analysts say other factors played a big role in reducing violence in Iraq, including a decision by former Sunni Arab insurgents to turn against al Qaeda and a ceasefire imposed by Shi'ite cleric Moqtada al-Sadr on his Mehdi militia.