Last Friday, Shiite protesters demanded the removal of a US military base from Sadr City in east Baghdad as US commanders reported a surge of attacks on troops in a province near the capital.
More than a thousand unarmed but angry Shiites spilled out of mosques after Friday prayers to demand the base be removed from their Sadr City bastion, in the first sign of Shiite opposition to a new security plan.
The protests came a day after one of Sadr City's two mayors who negotiated with the Americans and welcomed the creation of the fortified base was shot and wounded by unidentified gunmen. A policeman travelling with him was killed.
"No, no to America. No, no to Israel. No, no to Satan," the protesters chanted, their voices reverberating across the vast slum district in east Baghdad, a stronghold of cleric Moqtada al-Sadr.
US and Iraqi forces have been setting up joint security stations across Baghdad, including in Sadr city where US troops in 2004 fought bitter street battles with Sadr's black clad militias.
Since the crackdown began on February 14, however, the militia fighters have melted away offering no resistance.
But since the attack on the mayor, tension has begun to rise and a tract distributed among the crowds by Sadr's office denounced what it described as "bases for the occupier on the lands of Sadr City."
Sadr himself was not present -- the US military believes he has gone to ground in Iraq's Shiite neighbor Iran -- but supporters carried his portrait and read out a statement he had apparently sent to them.
"The occupiers wanted to distort the reputation of the city and issued propaganda saying there are talks and cooperation between you and them. I am confident that you regard them as your enemy," he said.
"Don't surrender to them. You are their betters," he added.