Is fate of U.S. surge in Iraq about to unravel?

BAGHDAD, Iraq - March 24, 2008 - A cease-fire critical to the improved security situation in Iraq appeared to unravel Monday when a militia loyal to radical Shiite Muslim cleric Muqtada al Sadr began shutting down neighborhoods in west Baghdad and issuing demands of the central government.

Simultaneously, in the strategic southern port city of Basra, where Sadr's Mahdi militia is in control, the Iraqi government launched a crackdown in the face of warnings by Sadr's followers that they'll fight government forces if any Sadrists are detained. By 1 a.m. Arab satellite news channels reported clashes between the Mahdi Army and police in Basra.

The freeze on offensive activity by Sadr's Mahdi Army has been a major factor behind the recent drop in violence in Iraq, and there were fears that the confrontation that's erupted in Baghdad and Basra could end the lull in attacks, assassinations, kidnappings and bombings.

As the U.S. military recorded its 4,000th death in Iraq, U.S. officials in Baghdad warned again Monday that drawing down troops too quickly could collapse Iraq's fragile security situation.

Pentagon officials said that military leaders are watching for any signs of backsliding as they consider whether to keep drawing down troops below pre-surge levels.

President Bush spoke about the death toll, saying, "One day, people will look back at this moment in history and say, 'Thank God there were courageous people willing to serve, because they laid the foundations for peace for generations to come.'"

Even as he spoke, the situation on the ground was rapidly worsening.