In three weeks or so, the top two Americans in Iraq, Gen. David Petraeus and Ambassador Ryan Crocker, will report their findings on progress there -- or the lack of it. The repercussions in Washington will be many, and they will be minutely scrutinized. But don't forget Britain, America's junior partner in Iraq. Prime Minister Tony Blair, President George W. Bush's dependable sidekick in the war effort, resigned in June. His successor, Gordon Brown, was, as Blair's No. 2, long suspected as being less committed to Bush's Iraq agenda than Blair was. As the post-war period in Iraq enters a new phase, Brown's allegiance to Bush could come under serious pressure.

For at least a year now, the British public has operated on the assumption that U.K. troops are headed for the exit in Iraq. Despite his reputation as Bush's subservient warrior "poodle," Blair drastically reduced U.K. troop numbers there, presiding over a sharp decline -- from 46,000-strong invasion force in 2003 to 8,500 in May 2005 to 5,500 before he left office. Even as Bush "surged" more U.S. soldiers into Baghdad and surrounding areas in recent months, Britain has stuck to its plans to draw down forces in the south further, with another 500 troops scheduled to go home this autumn when the U.K. turns Basra Palace over to the Iraqis and then concentrates its forces at Basra Air Station.

Amid signs that the security situation in southern Iraq is worsening, London may find it increasingly difficult to justify the pace of its withdrawal. Official Washington remains discreet when it comes to criticism of the prime minister, but already surrogates of the Bush administration are bombarding 10 Downing Street with the message: "Who Lost Basra?" The Washington Post recently quoted a senior US intelligence official in Baghdad as saying: "The British have basically been defeated in the south." Kenneth Pollack, a former CIA intelligence analyst and early advocate of the invasion of Iraq, maintains British military participation in Iraq "has been meaningless for some time." Gen. John Keane, a former vice chief of staff of the U.S. army and adviser to Petraeus who returned recently from Iraq, told the BBC that Basra is rife with "almost gangland warfare" and that with further British troop withdrawals, "the situation will continue to deteriorate."

What's a prime minister to do? Brown will be loathe to commit additional troops to Iraq. Most likely, he will attempt to continue to bring the numbers down slowly, appeasing the Americans with the fact that Britain is shouldering a disproportionate burden of the fighting in Afghanistan. There, the number of British troops has risen sharply in recent years and is expected to reach at least 7,700 troops by the end of the year. With the situation turning nastier in Afghanistan as British casualties rise, it would politically difficult, if not impossible, for Britain to up the ante in Iraq, an even less popular military enterprise. If Britain had to do add troops to Basra, the nature of Brown's premiership could change radically. Bush, scrambling to rescue his reputation from the conflagration of Iraq, recently described himself as a "wartime president." It's safe to say that the last thing Gordon Brown wants to be is a wartime prime minister.