BAGHDAD (Reuters) -- The new U.S. military commander in Iraq must find ways to keep improving security while U.S. troop levels are falling, Defense Secretary Robert Gates said as two Baghdad bombings underlined the scale of the task.
Gates will preside over a ceremony on September 16 to hand command of U.S.-led forces in Iraq to Lieutenant General Ray Odierno from General David Petraeus, whose term was marked by a "surge" of 30,000 extra U.S. troops and big falls in violence.
Arriving for his eighth visit to Iraq since he took over at the Pentagon in December 2006, Gates said the areas in which U.S. forces would be engaged in Iraq would continue to narrow.
"The challenge, I think, for General Odierno is: How do we work with the Iraqis to preserve the gains that have already been achieved, expand upon them, even as the numbers of U.S. forces are shrinking?" Gates told reporters on his plane.
Iraqi forces have led all big security operations in recent months. The U.S. military is also expected to transfer security control in two more provinces this year, putting Iraqi forces in charge of security in 13 out of the country's 18 regions.
But underscoring the security headaches that remain, two car bombs exploded in quick succession in the Baghdad district of Karrada, killing 12 people and wounding 34, police said.Promotion For Odierno
Odierno, who served as the No. 2 U.S. commander in Iraq for 15 months until February, will be promoted to full general on September 16.
President George W. Bush last week announced that around 8,000 U.S. troops would withdraw from Iraq by early next year, leaving around 138,000 in the country.
Many troops who were scheduled to replace those departing from Iraq will now head to Afghanistan, where insurgent violence has grown dramatically in the past two years.
Widely criticized for his handling of the first years of the Iraq war, Bush ordered a shakeup in late 2006 and early 2007, replacing Donald Rumsfeld at the Pentagon and picking media-savvy intellectual Petraeus as his new war commander.
Since then, violence in Iraq has declined to its lowest level in four years but Washington 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. 'Still Engaged'
Gates said it was important Iraqis move forward with reconciliation, that the government provide more services to its people, and that U.S. and Iraqi forces maintain pressure on Sunni Islamist Al-Qaeda militants and Shi'ite extremist militias.
He said last week he believed the Iraq war was entering its "endgame," now that the extra U.S. troops have departed and Iraqi forces are taking more responsibility.
"There is no question we will still be engaged," Gates said. "But the areas in which we are seriously engaged will, I think, continue to narrow."
Iraqi Defense Minister Abd al-Qadir Jassim praised Petraeus, who will become the top U.S. commander for the Middle East.
"General Petraeus has supported the Iraqi Army in many ways. His fingerprints [on it] will be very clear in the future and we will remember him," Jassim said at a farewell ceremony for Petraeus at the Ministry of Defense.'Historic' Role
Gates told reporters traveling with him that Petraeus had played a "historic" role in Iraq.
U.S. officials have lauded the surge of American forces, and an emphasis under Petraeus on troops getting into Iraqi communities to protect them, as a major reason for the decline in violence.
Officials and analysts say other factors played a big role, such as a decision by former Sunni Arab insurgents to turn against Al-Qaeda and a cease-fire imposed by Shi'ite cleric Muqtada al-Sadr on his Al-Mahdi Army militia.
Washington and Baghdad are also close to finalizing a security pact that will govern the presence of U.S. forces in Iraq when a UN mandate expires at the end of the year.