Iraqi soldiers hoists the nation's flag over the Basra palace after British troops withdraw

Iraqi soldiers hoisted the nation's flag over the Basra palace compound Monday after British troops withdrew from their last garrison in the city, leaving the country's second biggest city largely in the hands in the hands of Iranian-backed Shiite militias.

Photo: Iraqi soldiers hoists the nation's flag over the Basra palace after British troops withdraw

At al-Asad Air Base west of Baghdad, meanwhile, U.S. President George W. Bush made a surprise visit to Iraq, hoping to bolster his case that the buildup of U.S. troops is helping stabilizing the country.

And the U.S. command said a soldier was killed and three others injured when a roadside bomb blew up next to their patrol on Sunday outside of Baghdad. No further details were released.

British vehicles rumbled out of the gates of the sprawling Basra Palace compound after dark Sunday and headed for the Basra's international airport, about 20 kilometers (12 miles) away, where the last of Britain's 5,500 soldiers are based.

British Prime Minister Gordon Brown said the move was planned for months and that British troops would be available to help Iraqi forces "in certain circumstances.

"This is essentially a move from where we were in a combat role in four provinces, and now we are moving over time to being in an overwatch role," Brown told the British Broadcasting Corporation.

"We are able to give training. ... We are able to re-intervene in certain circumstances. The purpose of this has been to hand the security over from the British army to the Iraqi security forces."

Bush was joined by his top advisers, including National Security Adviser Stephen Hadley. Defense Secretary Robert Gates was traveling there separately. The mission to shore up support for the war was shared with only a small circle of White House staffers and members of the media, who were told that if news of his trip leaked early, it would be scrapped.

The White House arranged Bush's trip as a showdown nears with Congress over whether his decision in January to order 30,000 more U.S. troops to Iraq is working. Some prominent Republican lawmakers have broken with Bush on his war strategy, but so far, most Republicans have stood with Bush. In exchange for their loyalty, they want to see substantial progress in Iraq soon.