One of the big questions raised by the ground-breaking rapprochement between Iran and the West, and the diplomatic triumph of Iran's new reformist president, is how the Revolutionary guards, the country's elite military force, will take to the move away from decades of ideological hostility toward the West.

At first glance, the Islamic Revolutionary Guards Corps, known as Pasdaran in Farsi, has been one of the main targets of Western sanctions because it is seen asa major supporter terrorism and runs Iran's nuclear and ballistic missile programs, which lie at the heart of international economic crackdown that began in 2010.

Any deal that eases those punitive measures would presumably be welcomed by Iranians.

But the IRGC has long espoused unremitting enmity toward the West, the United States in particular.

Any political detente that erodes that doctrine, as espoused by the late Ayatollah Ruhollah Khomeini who founded the Islamic Republic in 1979, would run counter to the corps' ideological roots -- and its vast institutional interests.

The Pasdaran has led the opposition within Iran to the efforts of President Hassan Rouhani, elected June 14, to defuse the conflict with the West, largely by moderating Iran's contentious nuclear program, which hardliners see as an emblem of Iran's revolutionary might.

But the IRGC has been relatively quiescent, presumably because Rouhani clearly has the blessing of Iran's supreme leader, Ayatollah Ali Khamenei, to seek an end to the sanctions that have throttled Iranian oil exports and crippled the republic's economy.

Analysts worry the surprising absence of major displays of opposition suggests the commanders of the Revolutionary guards, founded by Khomeini himself to protect the Islamic purity of the revolution from just such liberal threats as this, are biding their time since most Iranians appear to be behind Rouhani's initiative.

"Since hostility toward the United States is as old as the Islamic Republic itself, many within the regime question whether Iran can be a truly revolutionary state, in line with the vision of its founders, if it normalizes relations with Washington," the U.S. global security consultancy Stratfor observed.

"All the pillars of power in Tehran are struggling with the change in tack, but the IRGC in particular fears that its institutional interests could be sacrificed. ...

"However, the corps realizes that talks are necessary for the future well-being of the regime, and thus does not oppose dialogue outright. Instead, it wants to ensure that its status as a major center of power in the Islamic Republic is not compromised.

"For this reason it has been campaigning to limit the scope of the diplomatic engagement with the United States," Stratfor noted.

"Its efforts have not gone well, given that most of the regime power centers are in favor of pursuing the diplomacy, and that its 34th anniversary of the U.S. Embassy hostage crisis demonstrations drew a crowd of only about 30,000."

The corps won nationwide respect during the 1980-88 war with Iran because of its troops' suicidal courage and human-wave attacks.

But that's been tarnished as it built up a vast commercial empire, with all the corruption and abuse of power that goes with such an undertaking.

Over the last decade alone, the IRGC and its associates have amassed at least $120 billion from so-called privatisations to acquire core national assets, The Financial Times reported.

Indeed, even before Rouhani embarked on his detente diplomacy, he was starting to move against the Pasdaran's business operations that allow it control much of the economy, hogging major energy and construction projects.

"The guards' economic interests have become too big and out of control," a senior government adviser said.

"It's almost impossible to estimate the force's total wealth because of its opacity," analyst Najmeh Bozorgmehr said. "Nevertheless some reckon the guards' companies and banks generate income of about $100 billion a year."

Rouhani was elected despite reported efforts by the guards to block his victory at the polls and that, Bozorgmehr noted, "could prove costly for the corps.

"The new government seems determined to reduce the guards' influence and carve out space for private companies that have been suffocated by its operations ... Rouhani's government has sensed that economic revival will require an attempt to curtail the influence of the guards."