Basra is reported to have been calm since fighting ended on Sunday
An Iraqi commander has led a convoy through the stronghold of radical Shia cleric Moqtada Sadr in Basra.
Correspondents say the convoy was intended as a show of force and that it met no significant resistance.
It went through the Hayaniya district - the scene of heavy fighting last week between troops and Shia militia.
Meanwhile, a senior American military spokesman said that some of the Iraqi security forces had not been "up to the job" during the fighting.
General Kevin Bergner told a news conference on Wednesday that "there is still much more work to do in developing and strengthening the capabilities of the Iraqi security forces".
"Overall", he added, "the majority of the Iraqi security forces performed their mission. Some were not up to the task and the government of Iraq is taking the necessary action in those cases."
The fact that Iraqi forces conducted the mission with limited US and British involvement, he added, had been a positive development.
"This is an instance", he said, "where the government of Iraq asserted itself, made a decision on the deployment of forces and took a very difficult position.
"The fact that it took such a decision and remained committed to it is significant, and is a reflection of the seriousness with which they take their responsibilities of security."
Hundreds of people were killed in last week's clashes which came after the Iraqi prime minister, Nouri Maliki, ordered an offensive against Shia militiamen in Basra.
The fighting ended when Moqtada Sadr ordered his fighters off the streets on Sunday.
Mr Maliki has described the operations in Basra as a success, claiming on Tuesday that it had "achieved the aim of imposing law in the city and restoring normalcy".
Basra is reported to be mostly quiet for a third day running although there are some reports of sporadic violence.
Correspondents say Moqtada Sadr's supporters fear the prime minister - also a Shia - wishes to weaken their movement before local elections due later this year.