A bomb has killed five people in the Baghdad stronghold of a Shia militia today.
The Mehdi Army of radical Shia cleric Moqtada al-Sadr said it would defend its neighbourhoods after a bomb, possibly a suicide attack, killed five and wounded eight in a minibus in the heart of Sadr City, a Shia slum in eastern Baghdad.
The area has been relatively immune from Sunni insurgent attacks, possibly because Sadr has sought alliances with Sunnis who share his nationalist, anti-American posture.
Elsewhere, in mainly Sunni west Baghdad, gunmen ambushed and destroyed the armoured limousine of Adnan al-Dulaimi, a veteran leader of the main Sunni political bloc - killing a bodyguard.
Mr Dulaimi himself had only just got out of the car because it had a flat tyre. As he resumed his journey in another vehicle, his guards were surrounded by assailants firing assault rifles.
The Shia-led interim government of Prime Minister Ibrahim al-Jaafari has struggled to respond to violence since the bombing of a Shia shrine in Samarra on February 22nd
At least 450 people, by the most conservative official estimates, have been killed in sectarian bloodshed since then.
The government has ordered thousands of police onto the streets of Baghdad, backed up by US troops, but their effectiveness is untested and their loyalties are uncertain in the face of sectarian militias to which many once belonged.
US and Iraqi leaders accuse al-Qaeda militants of bombing the shrine to drag Shias into a civil war that would wreck US plans. Some Sunnis say Iranian-backed Shias did it to justify reprisals against the Sunni Arab minority.