BAGHDAD (Reuters) - Anti-U.S. Shi'ite cleric Moqtada al-Sadr's brief return to Iraq after years of self-imposed exile in Iran could set off intra-Shi'ite struggles that might shake the country's stability just as U.S. forces withdraw.
The sectarian war between Sunnis who dominated Iraq under Saddam Hussein and the majority Shi'ites who rose to political power after his fall is fading.
Iraq is now hoping it can use its oil wealth to rebuild after decades of war, sanctions and sectarian war triggered after the 2003 U.S.-led invasion.
But any escalation of tension in Shi'ite ranks as a result of Sadr's re-emergence could cause a descent back into strife.
Sadr, an enigmatic leader of a popular movement that bears his family's name, came back to Iraq last month at least in part to confront errant followers who used his exile to establish their own power base and challenge his authority, insiders say.
His sudden departure back to Iran, much to the surprise of his own followers, raised speculations about threats to his safety and clout from some people among his inner circle.
Sadr arrived Iraq on Jan 5th, stayed about two weeks in the southern Shi'ite city of Najaf and left back to Iran on Jan 22.
"There are some factions who have benefited from his (Moqtada's) absence during those years," said a senior Sadrist, speaking like others on condition of anonymity due to the sensitivity of the issue.
"The movement was scattered after his departure," he said. A likely main foe of the young, black-turbaned cleric is a well-organised and lethal Shi'ite militia called Asaib al-Haq, which is believed to be getting funds and training from Iran.
Asaib split from Sadr's movement, and is blamed for attacks on Iraqi police and U.S. forces, as well as mortar rounds fired at Baghdad's fortified Green Zone neighbourhood.
"Iran needs claws...Asaib could be used to threaten anyone in Iraq, even Moqtada himself," said Fateh Kashef al-Gitta'a, director of Baghdad's al-Thagalayn Center for Strategic Studies.
Asaib al-Haq, or the Leagues of Righteousness, is headed by Qais al-Khazali, a spokesman for Sadr before he broke away. Asaib may be able to call up thousands of fighters and has its own television channel and websites that often broadcast its attacks on U.S. soldiers.
The group infiltrated the upper echelons of Sadrist ranks during Sadr's absence, making it hard to know who is truly loyal and who opposes him, sources close to Sadr said.
"Many senior Sadrists have strong relations with the Asaib," said a former senior member of Sadr's Mehdi Army militia. "It is easy for a coup to happen from within."
A somewhat diminished maverick whose Mehdi Army was once viewed by U.S. forces as the greatest threat to Iraq, Sadr's movement is making a stab at the political mainstream.
Winning 39 seats in an election last year, its support was crucial in securing a new term for Shi'ite Prime Minister Nuri al-Maliki. It has seven ministries in Maliki's government.
The scion of a revered clerical family whose fiery anti-U.S. message mobilised resistance to the 2003 invasion, Sadr's only public speech last month was met with booming cheers from rapturous followers.
Graffiti has appeared in the southern city of Kufa proclaiming "Yes, yes to Moqtada", and pictures of him are spreading in Najaf and Kerbala after being banned for years.
Infighting among the Sadrists could benefit Shi'ite rivals, such as the once dominant Supreme Islamic Iraqi Council (ISCI), founded in exile in Iran, or Maliki's Islamic Dawa party.
It could also open the door for more meddling from neighbouring countries such as Shi'ite power Iran as U.S. troops prepare to fully withdraw this year.
"Asaib is Iran's secret army in Iraq to be used against the Americans," said a senior Iraqi Shi'ite politician, close to both Sadr and Asaib.
"It was created to defend Iran in case of any attack ... They can set this country on fire."
Washington has accused Iran of supporting Shi'ite militias, a charge Tehran denies, and Iraqi Sunnis view Iran's intentions in Iraq with enormous suspicion.
But Iraqi Shi'ites are divided on the extent and strength of Iran's clout in Iraq and over Sadr himself.
"Iran could not tame Sayyed Moqtada," said the former Mehdi Army member.