WASHINGTON, March 26 (UPI) -- Fighting in Iraq's oil capital Basra isn't the first bloodshed between varying political and armed groups but may be the decisive battle for control over the oil sector, local government and the fate of the province.

This week Iraqi Prime Minister Nouri al-Maliki launched an Iraqi Security Forces offensive into Basra.

The violence that has killed dozens and injured hundreds since Tuesday is billed as Iraq's military against "criminals, terrorist forces and outlaws," in the words of Maliki. But political parties and their militias have gained a stronghold in Baghdad and Basra, from elected office to the security forces, police and those protecting the oil infrastructure. And the battle is looking more like two leading political parties against two disenfranchised parties, all Shiite Arab.

"It's an internal Shiite war for who is going to represent the Shiite community in Iraq," said Kenneth Katzman, a Middle East expert at the Congressional Research Service. The operation was planned a month ago, he said, and the target was the illegal activity like oil smuggling taking place under the control of the Fadhila Party and other armed groups.

The Mahdi Army of cleric Moqtada Sadr says it's the target of the Iraq Security Forces that have been infiltrated by the Badr Corps of the Islamic Supreme Council of Iraq. ISCI is a large and crucial member of the coalition government, along with Maliki's Dawa Party.