Anti-American Shiite cleric Moqtada al-Sadr, whose militia contributed to the bloodiest days of the Iraq war, made a surprise return to Iraq on Wednesday, ending nearly four years of self-imposed exile in Iran and raising new questions about U.S. influence here.

Sadr’s remarkable trajectory brought him home just as his political faction attains significant power, allied in Iraq’s new national unity government with Prime Minister Nouri al-Maliki, who just a few years ago moved to crush Sadr’s Mahdi Army.

It was Sadr’s recent decision to support Maliki for a second term, in a deal brokered by Iran, that ended eight months of political deadlock and allowed Maliki, also a Shiite, to cobble together his new government two weeks ago.

In another sign of Iran’s significant influence in Iraq, just as U.S. troops prepare to leave the country by the end of the year, Iran’s new foreign minister, Ali Akbar Salehi, met in Baghdad on Wednesday with Maliki and more than a dozen other government officials.

The Sadrist faction controls at least eight of about three dozen ministries in Maliki’s new cabinet and has vowed to become a full participant in the political process. But the return of Sadr leaves open the question of whether he will seek to reassert his influence solely through political means, or will instead revert to violence.

“That’s what everybody is holding their breath about,” said J. Scott Carpenter, who was serving as deputy assistant secretary of state for Near East affairs during Sadr’s rise and most violent clashes with U.S. forces.

“There are two views about Moqtada Sadr,” Carpenter said. “He is either trying to create a bastion for himself in the south of Iraq with his militia, like Hezbollah, or become part of the political process as a leader.”

The State Department reacted cautiously to the news of Sadr’s return, saying that it was an internal matter for Iraqis. Spokesman P.J. Crowley acknowledged that the cleric’s fiery rhetoric had helped fuel anti-American violence, but “what happens with him going forward is a matter for him and the government of Iraq,” he said.

“It is not for us to be for or against any particular leader or party in Iraq,” Crowley said.

He suggested that Iraq’s government and police could contain any new flare-ups of sectarian violence that might be triggered by Sadr’s return. “It’s one of the reasons we have worked so hard to build up the capacity of Iraqi security forces to handle whatever unrest might occur,” Crowley said.

A political journey

Sadr, believed to be in his 30s, shot to prominence in 2003 as the most outspoken Shiite opponent of the U.S. occupation. By 2004, his Mahdi Army was fighting pitched battles with U.S. forces in the streets of Baghdad and Najaf.

He fled to Iran in early 2007 after President George W. Bush’s announcement of a surge in U.S. troops, fearing he would be pursued under the terms of a 2004 arrest warrant against him in the killing of a rival Shiite cleric. Sadr said he wanted to become an ayatollah and was studying in Qom, Iran’s main center of Shiite Islamic learning. Sadr said he was working under Ayatollah Kazim al-Haeri, an Iranian cleric who became his chief religious guide after Sadr’s father, a grand ayatollah, was assassinated by Saddam Hussein’s forces in 1999.

But several analysts said it’s now clear that Sadr traveled to Iran not just for religious purposes, but for political ones.

“Sadr left Iraq because his political influence was waning and he thought he could regain that by achieving religious authority,” said Babak Rahimi, an Islamic studies professor at the University of California, San Diego who visited Qom in December and is preparing a paper on Sadr’s religious development. “Now things have changed. He’s already gained that influence. He was able to get Maliki’s attention and he’s returning a confident man, thinking it’s time for him to play a significant role in Iraqi politics.”

After Sadr arrived by plane in the Shiite holy city of Najaf with a team of bodyguards, he was quickly surrounded by a crowd of cheering supporters. He visited the Imam Ali shrine and the grave of his father, then returned to his family’s home around nightfall as well-wishers gathered outside.

A spokesman for Sadr’s Najaf office said that the cleric has returned to Iraq permanently and plans to transfer his religious studies to a renowned Shiite center in Najaf, adding that Sadr would “announce his agenda to the public” in coming days.

In October, Sadr and Maliki embraced publicly at a meeting in Qom, ending years of bitter rivalry that peaked with Maliki’s 2008 attempt to crush the Mahdi Army. Many Iraqis speculated that Sadr did not dare to go home for fear of being detained, but his return suggests that his understanding with Maliki includes guarantees that he would not be arrested.

The warrant for his arrest was issued by an Iraqi judge in 2004, during the rule of the U.S. Coalition Provisional Authority. But under the terms of the U.S. security agreement with Iraq, U.S. troops no longer have the authority to act on arrest warrants.

Khalid al-Assadi, a lawmaker and Maliki’s spokesman in the State of Law party, said Sadr’s return was welcome but nothing that the government would comment on.

“The returning of Moqtada is a very normal thing because he is an Iraqi, and he is most welcome in his country,” Assadi said. “In the past, there were circumstances that prevented his coming. Now the situation is different.”

Iranian connections

There are large gaps in what is known about Sadr’s Islamic tutelage in Iran, Rahimi said, including whether he ever worked one-on-one with Haeri. Rather, there were suggestions in Qom that Sadr was actually studying more in Tehran, under Mohammad Taghi Mesbah Yazdi, Iranian President Mahmoud Ahmadinejad’s spiritual adviser, or that he was working with a combination of clerics, Rahimi said.

A senior Sadrist in Najaf said Wednesday that Sadr was studying under a cleric close to Iran’s supreme leader, Ayatollah Ali Khamenei.

“The thing that seems most likely is that he trained under someone with hardline influence . . . and therefore he has the backing of Tehran,” Rahimi said.

Mehdi Khalaji, a senior fellow at the Washington Institute for Near East Policy who studied for 14 years in Qom to become an ayatollah, said that, no matter who he was working with, Sadr had not studied long enough to become an ayatollah and was not among the small number in Qom known to be taking high-level classes.

To supporters in Najaf, meanwhile, Sadr’s academic pedigree was less important than his presence.

In a crowd of thousands outside Sadr’s home on Wednesday, Ali al-Asady, 33, identified himself as a member of the Mahdi Army and said it was important that the cleric returned at a such a critical time for Iraq, when U.S. forces are leaving.

“We thank God for the return of our good and wise leader,” he said.

Sarhan is a special correspondent. Davis reported from Baghdad. Correspondent Liz Sly and staff writer Joby Warrick in Washington and special correspondent Ali Qeis contributed to this report.