"It is important to show the Iraqi people that we do not desire our forces to remain any longer than they are needed, but whilst they are needed, we will be at their side," Blair told Parliament.
"The situation in Basra is very different from Baghdad. There is no Sunni insurgency. There is no Al Qaeda base. There is little Shia-on-Sunni violence," despite "often intense fire" from Shiite militias targeting British troops, he said.
"What all of this means is not that Basra is how we want it to be. But it does mean that the next chapter in Basra's history can be written by Iraqis," Blair said.
Most analysts say the prime minister's assertion that significant progress had been made in securing southern Iraq stretched the facts. Though the south is not nearly as violent and chaotic as the capital and the Sunni heartland to the west, it remains jittery, unstable and frequently bloody. Shiite militias and armed gangs lord over such cities as Basra and Amarah, as well as the long, desolate stretches of roadway through the marshlands and deserts of the south.
British bases in Basra regularly come under mortar fire. British troops engage in almost daily gunfights with militiamen. In recent months, the British all but evacuated their downtown base and moved to a more secure site on the grounds of the city's airport.
Bastion for Islamists
A study on the south issued this week by the Washington Institute for Near East Policy, a think tank that has been sympathetic to the Bush administration's foreign policy goals, describes southern Iraq in dire terms. It notes that Basra, once one of Iraq's more liberal and cosmopolitan cities, has become a bastion for Islamists who use the south's vast oil wealth to "fill their war chests."
"The province has suffered one of the worst reversals of fortune of any area in Iraq since the fall of Saddam [Hussein]'s regime," the report says.
Military and political analysts said a British drawdown in the region could leave a vacuum that could provide shelter to militiamen displaced during stepped-up U.S.-Iraqi operations in Baghdad, in a location where Iranian influence is great.
Equally serious, they said, is the fact that Basra and its environs are a crucial supply link to U.S. forces in Baghdad.
"The fear is essentially that when the U.K. pulls out, the militias will come to control the situation, rather than the Iraqi army," said Michael J. Williams, head of the transatlantic program at the London-based Royal United Services Institute.
Although U.S. and British leaders have taken pains to deny any split in policy over Iraq, "if the security situation in Basra was perfect, should the Brits be withdrawing troops, or reallocating them someplace else where they're needed, which is Baghdad?" Williams said.
"The fact is that the troops that work best alongside the Americans are leaving the country," he said.
Times staff writers Borzou Daragahi in Baghdad and James Gerstenzang, Paul Richter and Peter Spiegel in Washington contributed to this report.
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British Prime Minister Tony Blair wants to withdraw about 1,600 troops from Iraq in coming months. Here's a look at some of the nations contributing military personnel in Iraq and how their troop levels have changed since the war began in March 2003:
*--* X Oct. 2003 Dec. 2005 Current United States 130,000 160,000 132,000 Britain 7,400 8,000 7,100 South Korea 675 3,200 2,300
South Korea: Approved a one-third reduction of its forces last year.
*--* Australia 0 900 1,450 Romania 800 863 1,000 Poland 2,400 1,400 900
Poland: Last fall authorized the extension of its troops and will pull them out by mid-2007.
*--* Georgia 70 900 850 Denmark 400 530 300
Denmark: Announced Wednesday that it would withdraw its ground troops from southern Iraq by August and replace them with 55 soldiers in a helicopter unit.
*--* El Salvador 360 380 380 Bulgaria 485 380 153 Czech Republic 300 102 96 Italy 3,000 2,800 0
Italy: Pulled its last troops out in September.
*--* Netherlands 1,100 19 0 Spain 1,300 0 0
Spain: Ordered its troops out soon after the 2004 train bombings in Madrid that killed 191 people.
*--* Ukraine 1,650 876 0 Japan 0 600 0
Japan: Last year, ended its controversial deployment, its first significant military involvement since World War II.
*--* Honduras 360 0 0 Thailand 400 0 0
Numbers are based on best estimates from sources listed
Sources: Associated Press, Agence France-Presse, GlobalSecurity.org, Times reports and wire services. Graphics reporting by Scott Wilson, Mike Young