Rome ? Italy’s prime minister announced plans Tuesday to start drawing down his country’s 3,000-strong contingent in Iraq in September, putting a fresh crack in President Bush’s crumbling coalition. Bulgaria also called for a partial withdrawal, and Ukraine welcomed home its first wave of returning troops.

The moves come on top of the withdrawal of more than a dozen countries over the last year and could complicate efforts to keep the peace while Iraq’s new government builds up police and military units capable of taking over from foreign forces.

Two years after the U.S.-led invasion toppled Saddam Hussein, the coalition is unraveling amid mounting casualties and kidnappings that have stoked anti-war sentiment and sapped leaders’ resolve to keep troops in harm’s way.

Italian Premier Silvio Berlusconi, who confirmed he would seek re-election next year, alluded to the rising public discontent and said he had spoken with British Prime Minister Tony Blair, another strong Washington ally. “We need to construct a precise exit strategy, also because our publics’ opinions expect this communication and we agree to talk about it soon.”

As of now, the reduction in the Italian contingent will start “even before the year’s end, in agreement with our allies,” Berlusconi added.

Italy’s government, a staunch U.S. ally, had vowed to stay despite suffering 21 casualties and enduring fierce public opposition that escalated this month after U.S. soldiers in Baghdad fatally shot an Italian intelligence agent escorting a newly freed hostage.

Asked whether the shooting played a role in Berlusconi’s decision, White House spokesman Scott McClellan said, “I’m not sure I’d make a connection there … I haven’t heard any comment to that effect from Italian officials.”

Thirty-eight countries have provided troops in Iraq at one point or another. But 14 nations have permanently withdrawn since the March 2003 invasion, and today’s coalition stands at 24. Excluding U.S. forces, there are 22,750 foreign soldiers still in Iraq.

About 150,000 U.S. troops shoulder the bulk of the responsibility.