Today the AP reports:

Putting more U.S. soldiers in the streets of Baghdad risks a new showdown with a radical anti-American cleric who has modeled his movement after Lebanon's Hezbollah guerrillas.

Muqtada al-Sadr's Mahdi Army has re-emerged as a key force in the majority Shiite community after suffering substantial losses during two uprisings against the U.S. military in 2004.

In Paul Bremer’s book, My Year in Iraq, he noted that Powell pressed for an attack on the Muqtada al-Sadr and his militia early on. In fact, Bremmer writes that when the first attack on his militia was about to commence, Powell told the president, the vice president, and others:

It's not just a question of his militia. At the end of the operation, Muqtada's got to be gone. (page 331)