The top U.S. civil administrator for Iraq, L. Paul Bremer, today called al-Sadr an "outlaw" and said he will not let the radical Shi'a cleric push the country into chaos.
"[Al-Sadr] is effectively attempting to establish his authority in the place of the legitimate authority of the Iraqi government and the coalition, and -- as I said yesterday -- we will not tolerate it."
In a sermon last week, al-Sadr mentioned attacks by what he called "the occupiers" and told his followers to "be on the utmost readiness and strike them where you meet them."
Bremer condemned the remarks, saying al-Sadr "has called for attacks on Iraqi forces and on the coalition, and he has actually conducted attacks with casualties yesterday, with dead among both the coalition and Iraqi forces."
U.S. helicopter gunships opened fire today on al-Sadr's private army during fierce gun battles in the western Baghdad district of al-Showla. Yesterday, battles between al-Sadr's militia -- said to number in the thousands -- and U.S.-led forces in Baghdad and several other cities killed at least 90 people.
The protests mark the first major clashes between the coalition and Iraq's majority Shi'a population, who until now have largely been tolerant of the U.S. occupation.
Protesters chanted: "Yes! Yes! Muqtada! No! No! America! No! No! America!"
There is nothing new in al-Sadr's anti-U.S. statements. Over the past year, he has appealed to Iraq's impoverished and uneducated Shi'a with a fierce anti-occupation message. But violence had, until now, been relatively infrequent.
The current tensions were sparked by Bremer's decision to close al-Sadr's newspaper, "Al-Hawza," on 28 March. Bremer ordered the paper shut for a few months because of what he said were its incitements to violence. The coalition last week also arrested one of al-Sadr's top aides, Mustafa al-Ya'qubi, in connection with the murder of a moderate Shi'a cleric last April.
Al-Sadr -- who is believed to be around 30 years old -- comes from a powerful clerical dynasty. He is the son of Grand Ayatollah Muhammad al-Sadr, who was killed in 1999 by agents presumed to be working for then-President Saddam Hussein, thus becoming one of the major symbols of Shi'a resistance to the former regime.
Larbi Sadiki, a lecturer on Middle East politics at Exeter University in Britain, said al-Sadr is a populist who has managed to successfully exploit growing discontent among the Shi'a. However, Sadiki said al-Sadr is too young and inexperienced to be a serious leader and that the hierarchy of Shi'a spiritual leaders in Iraq still support the country's leading cleric, Grand Ayatollah Ali al-Sistani.
Al-Sistani has reportedly appealed for calm after the weekend violence.
"[Al-Sadr's influence] is not really so wide as the power base and followers of Sistani," Sadiki said. "Sistani is unique."
Sadiki said that if al-Sistani had called for rebellion, the situation in Iraq would be much worse than it is now. "One word from Sistani and I think really the whole thing will go up in smoke. There is no doubt about that," Sadiki said. "If it was Sistani -- that's the question you should be asking. If it was Sistani who ordered basically a complete rebellion or public disobedience, I think it would be full-on conflict, full-on war."
But Sadiki added that al-Sadr nevertheless should not be underestimated. "Al-Sadr comes from a family of learned scholars. [His father] was killed, as you know. He's a got a tribal, clan base, which is probably powerful," Sadiki said.
Last autumn, al-Sadr created his militia to fight immorality in Iraq and so-called "alien ideology." At the time, he pledged that the militia would take not take up arms against occupying U.S. troops, saying its aim was to maintain peace and security.
Al-Sadr also had made no effort to hide his contempt for the 25-member Iraqi Governing Council, whose members -- including a representative from the Supreme Council for the Islamic Revolution in Iraq (SCIRI), the best-organized Shi'a party -- were chosen by the United States.
Muhammad Abd al-Jabar, a spokesman for the newly established Democratic Islamist Movement, a Shi'a political party, said al-Sadr's popularity is directly related to the U.S. failure to maintain law and order in the country following the invasion. He said Iraqis are tired of electricity shortages and the lack of security.