This makes more sense than anything else I have seen:
Robert's Stochastic Thoughts: Glanz and Rubin note "many Iraqis have recently speculated, Mr. Sadr's stock has recently fallen in Iranian eyes."... Still I note the extreme similarity of the position of the Mahdi army and the Islamic Republic of Iran. Neither denounces or resists the exercise of Iraqi sovereign authority in Basra. Each denounces and opposes the same in Sadr city. Ambassador Qumi went on to denounce fighting in Sadr City:
Strikingly, however, Ambassador Qumi simultaneously condemned American-led operations against the Mahdi Army in the Shiite enclave of Sadr City, where major new clashes broke out on Saturday. He said the American-backed fighting in that densely populated district was causing only civilian casualties rather than achieving any positive result.
>>"The American insistence on coming and having a siege on a couple of million people in one area and striking them with warplanes and shelling them randomly -- many innocent people will be killed through this operation," Mr. Qumi said. "The result of this operation will be the sabotage and destruction of buildings, and many people will leave their homes."
The events in Basra, in contrast with the Mahdi Army's continued fighting in Sadr City, renewed questions about where the Sadrist movement stands in Iraq's unstable political landscape.
Glanz and Rubin note that, given the extreme closeness of the Iranian and Iraqi governments, it is very likely that Iran approved the Basra offensive including the initial unsuccessful Basra offensive
Because leaders of the council and its armed wing spent years and sometimes decades in exile in Iran during Saddam Hussein's regime, it was assumed that the silence of the Badr Organization during the Basra offensive indicated that Iran had given at least tacit approval for the move.
In fact, IIRC al Sadr didn't denounce it immediately but just warned that they Iraqi government forces better not mess with the Mahdi army.
That would leave criminal gangs and Fadhila as targets of the offensive. On March 26 Michael Kamber and James Glanz wrote in The New York Times
In the weeks leading up to the operation, Iraqi officials indicated that part of the operation would be aimed at the Fadhila groups, who are widely believed to be in control of Basra's lucrative port operations and other parts of the city. The ports have been plagued by corruption, draining revenue that could flow to the central and local governments. But the operation also threatens the Mahdi Army's strongholds in Basra.
This suggests an alternative interpretation of recent events (put your tinfoil hat on).
There was an agreement between the people who count in Iraq -- al Hakim, al Sadr, al Maliki, al Sistani and Khameini -- to do something about Fadhila. al Maliki and al Hakim tried to use the operation to weaken the Mahdi army too. Their representatives were called to Qom and called to order by the head of the Martyrs Brigade of the Revolutionary Guard. A second try at a reasonable operation in Basra in which only anti-Iranian militias will be disarmed is in course (this would mean UK soldiers just went into the field to support Iran in an Iran vs UK proxy war without understanding what was going on).
However, al Maliki and al Hakim are still making trouble in Sadr city. Iran and al Sadr firmly warn them to stick to the plan. This would make al Mahdi's threat not bluster to hide his weakness, but a reminder of an agreement: "If you do not stop we will announce a war until liberation."
The day's events would still be good news. The difference is really a difference in guesses about what role Iran sees for the Mahdi army. In any case, it would be good if Iran could prevent their many allies in Iraq from fighting each other. I don't like the idea of a major role for al Sadr but, hey, al Hakim and al Mailiki are almost equally horrible.
As for the possibility of an Iraq genuinely independent of Iran, well, I am willing to speculate, but not to fantasize.