It also has sparked a fierce verbal campaign on both sides aimed at swaying Iraqi and international public opinion.
A typical broadside from al-Sadr's camp -- delivered by one of the cleric's aides, Qays al-Khazali -- took this form yesterday: "The uprising will continue until our demands are met, and if U.S. forces continue this escalation against the Iraqi people, the uprising will spread until it reaches Kurdistan in the north."
Al-Sadr's immediate demands are that the coalition withdraw all forces from populated areas and free his arrested supporters. Al-Sadr welcomed the overthrow of Saddam Hussein last year but has since refused to recognize the U.S.-led occupation and does not cooperate with the Washington-appointed Iraqi Governing Council (IGC).
But if al-Sadr's group is intent on trying to convince the public that its armed insurgency will soon spread across Iraq, coalition leaders are just as determined to portray the ongoing fighting as the work of a small and isolated minority of malcontents.
The top U.S. administrator in Iraq, L. Paul Bremer, told a U.S. television network yesterday that al-Sadr's supporters are an "illegal militia run by an outlaw." "It is not a Shi'a uprising. It is a militia, an illegal militia, run by an outlaw, a group of people who have attacked, first and foremost, Iraqis -- Iraqi police, Iraqi army, the Iraqi civil defense force, and coalition forces and Americans," Bremer said. "And we will deal with them. That is not the view of the majority of the Shi'a."
From the safety of that sensitive location, al-Sadr has sought to present himself as the unifying symbol of the Iraqi insurgency.
He has expressed hope that "Sunni brothers will succeed in liberating their region," a clear reference to the ongoing battle between coalition forces and anti-U.S. fighters in Al-Fallujah. There has been no clear reply from Sunni insurgents, who are generally believed to be loyalists of the Hussein regime, which oppressed the Shi'a majority. But press reports have quoted al-Sadr supporters as saying they have been joined in some street battles by Sunni militants.
At the same time, al-Sadr has tried to paint himself as acting in tandem with preeminent Shi'a leader Grand Ayatollah Ali al-Sistani. Al-Sadr said yesterday that "I proclaim my solidarity with Ali Sistani, and he should know that I am his military wing in Iraq and wherever he so desires."
Behind this war of words, how much support does al-Sadr have, and could his appeal grow even further? Analysts say al-Sadr -- a 30-year-old midlevel cleric -- is now at a crossroad. Despite his proclamation of solidarity with al-Sistani, he has not gained the support of the grand ayatollah, who has issued calls for calm instead.
A representative of al-Sistani repeated those calls yesterday as he visited al-Sadr in Al-Najaf. Shaykh Abd al-Mahdi al-Karbalai said, "We appeal for calm and restoration of public order, and we hope to settle this problem peacefully." The representative also said that "dialogue was possible" and that "firing without any reason was not justified."
Al-Sistani's opinions carry the weight of law within the Shi'a community, but al-Sadr's camp did not say whether the younger cleric will bow to the ayatollah's wishes.
Neil Partrick, a regional specialist at the Economist Intelligence Unit in London, says that al-Sadr is not likely to win mainstream Shi'a support without al-Sistani's backing. But the analyst says there is a danger that any U.S. crackdown on the insurgency that inflicts high casualties could severely test al-Sistani's ability to maintain calm.
"Ali Sistani has made it clear that he does not and continues to oppose the use of armed action and believes in negotiation. His difficulty is, of course, that in the context of dealing with the insurgency, military action has been taken of a fairly heavy-handed nature in some places, and this arouses fellow feeling among Shi'a," Partrick said.
Partrick continued: "But I think there are few signs that although there will be sympathy for Muqtada [al-Sadr] and certainly for the deaths of ordinary Shi'a in the context of this campaign, there are few signs that majority Shi'a opinion or indeed the Shi'a religious and political leadership that is primarily working with the U.S. coalition forces will actually go over to supporting violent insurrection. There are frustrations with the political timetable, but ultimately, of course, it leads to elections and effectively to majority Shi'a rule -- and that is not something which most Shi'a wish to upset."
Relations between al-Sistani and al-Sadr are complicated in part by the fact that the younger cleric has sought to boost his stature in the Shi'a community at the older leader's expense. The two men head rival networks of religious foundations. Al-Sadr inherited his position when his father, a grand ayatollah of equal stature to al-Sistani, was assassinated by presumed agents of Saddam Hussein in 1999.
The young cleric has previously harshly criticized al-Sistani's camp as being too passive in the face of the U.S. occupation. Al-Sistani has always refused to meet directly with U.S. authorities but approves of Shi'a parties participating in U.S.-led efforts to create a democratic system in Iraq.
But even if prospects appear slim that al-Sadr's insurgency will dramatically widen, it remains far from clear whether arresting the cleric will put an end to his political career.
Analysts at two U.S. military schools warned yesterday that extracting al-Sadr from his office in the holy city of Al-Najaf and placing him behind bars could only bolster the image he has sought to build of being a leading nationalist figure.
Vali Nasr, a professor of Middle Eastern and South Asian Studies at the Naval Postgraduate School in California, said Washington has to be very "watchful" about the way it detains al-Sadr. Nasr told Reuters that "already the idea of a young man, a cleric, standing up for justice against an overwhelming military machine has a lot of Shi'a symbolism." He added, "The U.S. has to be very watchful [about] going into a Muslim shrine, going into Najaf [to arrest him]."
W. Andrew Terrill, a national-security research professor at the Army War College's Security Studies Institute in Pennsylvania, agreed. Terrill said that "to the extent [al-Sadr] can mold [an arrest] into the propaganda that, 'I'm the one who's really fighting for Iraqi nationalism, while everyone else is collaborating,' it's going to make his standing within Iraqi politics much more formidable."