The motivation for a major offensive in Basra that was almost certain to force the Sadrists to have a de facto end to their mostly unilateral ceasefire has been bugging me. It does not make a whole lot of sense, especially as the primary prize in Basra, the oil export revenue, is easily deniable by any group with some popular support and access to high explosives, AND the forces committed to the fight are a single light army division and three brigades of police. That force level is absurdly low, especially if there is any reason to believe that there is significant chance of defections.
One of his big problems is that the Sadrists will beat him politically and can go even with him on the corruption and distribution of spoils. So he has to take down Sadr or at least massively rejigger the political equation. And this offensive is his attempt to do so, and it has two interesting option trees. The first is that it actually works in defeating and seizing (intact) the Basra oil export profit center. This allows for a zero-sum transfer of spoils from Sadrists to Maliki's coalition while also embarrassing and weakening the Mahdi Army and enhancing the prestige and loyalty of Badr loyal units. This is very unlikely for multiple reasons. The other option tree is far more interesting.
Let us assume that this is a deliberate provocation exercise.
In this scenario the Iraqi Army attack into Basra's Mahdi neighborhoods does not go well, but it provokes a national Sadrist response which starts a strategic countdown clock. This count down clock includes increased Sadrist/JAM actions against Iraqi government and US Forces such as rocket/mortar attacks on the Green Zone, and attacks against the oil export infrastructure. It includes concerns over US logistics lines as the combination of Basra shutting down and general insecurity in the Shi'ite bridge cities increases.
It puts MNF-I in a very tough position as MNF-I is justifiably paranoid about its supply lines and the new routes coming in from Jordan to Anbar and terminating near Baghdad are insufficient to adequately supply the entire force. The supply lines are much harder to hit today than they were in 2004 but they are still the weak point of the American presence. Additionally the level of fighting increases significantly so SOMETHING HAS TO BE DONE.
And that something could be the deployment of American combat troops to Basra, as reports indicate that Marines may be sent to Southern Iraq. The British could provide logistic base security as the Marines bail out the Iraqi Army and take over patrolling activities in Basra. And unless the live and let live arrangment that minimized conflict in Sadr City is quickly put into place, the Marines and the Sadrists will be knocking each others heads in. There will be a strong temptation on the Sadrists fighters to horizontally escalate and raise the level of their activities and attacks in other southern cities. This will be a good test to see how much control Sadr and other senior leadership really have over JAM activities or if they just provide strategic guidance.
If there is horizontal escalation of fighting to other southern cities, two things will happen. The first is that implicit working relationship that MNF-I has been building with elements of the Sadrist movement is scuttled. The second is that the South is now too unstable to have free and fear elections due to those 'thugs' and that elections are suspended until peace breaks out (and coincidentally Sadr and his followers are either killed or de-legitimized. )
This is pure speculation, but as Cernig points out in his post on this subject, everyone is looking for informed speculation as to motive.
Maliki decided to launch the offensive without consulting his U.S. allies, according to administration officials. With little U.S. presence in the south, and British forces in Basra confined to an air base outside the city, one administration official said that "we can't quite decipher" what is going on. It's a question, he said, of "who's got the best conspiracy" theory about why Maliki decided to act now.And this is not that outlandish of a conspiracy theory as there are few hard to reconcile with reality assumptions in it.