More than 30 people have been killed in renewed fighting in Sadr City, the mainly Shia district of Baghdad where American forces have repeatedly clashed with fighters loyal to the radical cleric Moqtada Sadr.
Shia militiamen who had fought in Najaf are now back in Baghdad
It's almost two weeks since the dramatic return to Iraq of an elderly religious leader, Ayatollah Sistani, brought about an end to the dangerous standoff in the Shia holy city of Najaf.
But the young cleric at the centre of that drama - Moqtada Sadr - continues to be a thorn in the side of the Iraqi government of Iyad Allawi.
Mr Sadr emerged from Najaf with his prestige high and his militia intact.
Buoyed by the outcome, he called on his forces throughout the country to observe a ceasefire - and announced he was entering politics.
But many of his fighters who returned to their homes in the sprawling suburb of Sadr City in Baghdad were soon engaged in a series of clashes with American forces.
The young cleric considers Sadr City as his fiefdom - and has demanded that US soldiers keep out.
But that's not a demand that either the Americans or the Allawi government are in a position to accept.
It's bad enough that some of the main Sunni towns west and north of Baghdad - notably Falluja and Ramadi - are under the control of militant groups and have become virtual no-go areas for US forces.
To allow that to happen in part of the Iraqi capital is unthinkable for them.