Even as observers blame Iranian influence for the collapse of Lebanon’s coalition government Wednesday, the mullahs in Tehran seem to be extending their reach into the fledgling government in Iraq.

When Moqtada Al Sadr landed in the southern Iraqi city of Najaf last week after three years of self-imposed exile, he was greeted with adulation and cheers by his followers. His anti-American rhetoric remained apparent at his first public rally this weekend.

The Shiite Muslim cleric who had led a violent insurgency against U.S. forces and the one-time public enemy number one for the U.S. military was given a hero’s welcome after playing a key role in helping Iraq’s Prime Minister Nouri al Maliki form a government last month.

Fox News has now learned that some members of the U.S. military worked for more than a year to get Sadr back from Iran.

“Although his rhetoric is disruptive, it is better he is in Iraq than Iran,” a senior military commander told FOX News. “From Iran he is controlled and used by Iran.”

But even with him home, Sadr ties to Iran’s regime are still cause for concern for many.

Sadr’s political party won 40 out of 325 seats in recent parliamentary elections, and his political allies have been given eight seats in Maliki’s cabinet.

The Sadrite militia, the Mahdi Army, called a ceasefire with the Iraqi Army in 2008, and there are signs that it has splintered and Sadr’s followers have moved on.

“I think he recognized that after three years in Iran, he was out of the game. The movement was proceeding without him,” said former U.S. Ambassador to Iraq Ryan Crocker in an interview. “They've made some decisions that obviously he would have been involved in. The most important one being to behave like a political party rather than a gang of thugs. I would expect some tension within the movement because of his return, you may even see some splits, and that, of course, from the U.S. perspective would be no bad thing.”

The cleric, still in his 30s, fled to Iran just months after the “surge” began in 2007 to avoid arrest or assassination. It was also seen as a bid to bolster his religious bona fides by going to the city of Qom to study with some of the same clerics who reportedly serve as spiritual advisers to Iranian President Mahmoud Ahmadinejad.

Iran’s embrace of Sadr and its former use of the Mahdi Army as proxy fighters against U.S. troops and the Iraqi government of Nouri al Maliki is similar to its use of Hezbollah in Lebanon. Hezbollah, like the Mahdi Army, eventually entered politics. But Hezbollah was allowed to keep a well-financed armed wing as part of a power-sharing agreement..

Hezbollah used its political clout to bring down the government of Prime Minister Rafiq Hariri today as he met with President Obama at the White House. The move is likely tied to the expected release of a U.N. report linking Hezbollah leaders, and in turn its Iranian and Syrian benefactors, to the assassination of Prime Minister Rafiq Hariri, father of the current prime minister.

Middle East experts worry that through Sadr, Iran has could have the same power over al Maliki’s new government in Iraq. Maliki travelled to Qom in October and was photographed embracing Sadr before convincing Sadr’s party to help him form a government. Some argue Sadr has played the role of kingmaker in the current government and could topple the fragile coalition if his demands aren’t met.

One looming point of conflict is the scheduled withdrawal of all U.S. forces from Iraq by the end of this year. Sadr is unlikely to tolerateany extension, even a temporary one, if the security situation won’t allow a full withdrawal.

“My prediction is that there will be some U.S. force level remaining in Iraq under some auspices,” Crocker told FOX News. “That is my prediction.”

That may not be good enough for Sadr, who along with his Iranian benefactors, wants all U.S. troops to leave on time. Iran’s rising role and influence in Iraq was seen this week as the Iranian foreign minister visited Maliki in Baghdad.

But there is some disagreement about just how much influence Iran will have over the fledgling Maliki government.

“I think there is sometimes a tendency to overstate just how great that influence is. The harder the Iranians push in Iraq, the more the Iraqis tend to push back,” Crocker said. “They have got a long bloody history. They fought an eight year war….So while the Iranians can cause trouble, Iraqis are tough customers and they can push right back as they have done.”

The return of Sadr to Iraq and the assertion of power by Hezbollah in Lebanon, others argue, should provide a cautionary tale for U.S. diplomats and the Obama administration which came into office talking of engaging Iran but has made no concrete progress in doing so. Iran, meanwhile, continues to move stealthily with proxies such as Hezbollah and Sadr to exert its influence throughout the region.

Jennifer Griffin currently serves as a national security correspondent for FOX News Channel . She joined FNC in October 1999 as a Jerusalem-based correspondent. You can follow her on Twitter at @JenGriffinFNC.