For a country high on George W. Bush’s hit list, Iran has been surprisingly friendly toward the United States of late. Earlier this month Iran blocked the escape of about 250 Ansar al-Islam radicals across the mountainous Iraq-Iran border, forcing them to surrender to U.S. and Kurdish forces. During the U.S. attack on Ansar, American warplanes used Iranian airspace–and Tehran turned a blind eye. True, Iranian leaders have condemned the U.S. “army of occupation.” And Washington fears that some of the senior Afghan-trained Ansar jihadis were spirited away by sympathizers in Iran last month. But, says one Western diplomat in Tehran, there’s no doubt that Iran has been at least “helpfully neutral” toward the Coalition during this war. It seems to have paid off: while U.S. Defense Secretary Donald Rumsfeld has been sniping at Syria for allowing military equipment into Iraq and for aiding fleeing Iraqi Baathists, the administration has been strangely silent on Iran.

In part, Tehran’s conciliatory attitude is dictated by self-preservation. Iran has nothing to gain, and lots to lose, by antagonizing a superpower on the warpath. But there are more subtle reasons. Reformers like President Mohammed Khatami “genuinely want a rapprochment with the United States, sooner or later,” says the former Turkish ambassador to Iran Turgut Tulumen. They also know that confrontation with the United States would strengthen support for religious hard-liners, who oppose detente.

The mild U.S.-Iran rapprochement is sure to be tested in the months ahead, as the process of forming a new Iraqi government unfolds. Washington wants to find a leader for Iraq’s Shiite majority who is at once pro-Western, popular–and not in Tehran’s pocket. That will be a tough task; all the major Iraqi Shiite exile groups are either based in or influenced by Iran.

Even now both Tehran’s liberals and conservatives want to extend Iran’s influence among Iraq’s 65 percent Shiite population. The reformist-controlled state television company has already made a bid for Iraqi hearts and minds by opening an Al-Jazeera-style TV station, Al-Alam, broadcasting in Arabic from terrestrial transmitters along the Iraqi border. The hard-liners caused an uproar in February by allowing up to a thousand Iraqi Shiite exiles–trained by Iran’s Revolutionary Guards and known as the Badr Brigade–to cross into northern Iraq. Since then the Badr Brigades have lain low–but up to 9,000 more are waiting in Iran, claim their leaders. That could spell trouble for a U.S.-controlled administration.

The figure Tehran supports in Iraq is the Ayatollah Baqir al Hakim, head of the Supreme Council for the Islamic Revolution in Iraq (SCIRI). It’s the only Shiite group with seats on the U.S.-supported Iraqi Opposition Council, and Hakim’s brother Abdulaziz met with senior U.S. officials in Washington last year. But though SCIRI signed off on opposition declarations, Hakim now says he may boycott the U.S.-efforts to form an interim government. “We are Iraqis. We do not need U.S. permission or coordination,” says a SCIRI spokesman. Washington may be encouraged by one thing. Ayatollah Hakim has said he doesn’t want to create an Islamic republic in Iraq.

It’s too soon to say which Shiite exile group will prevail. But the long struggle between Iranian reformists and hard-liners will play a huge role in Iraq’s new government–and whether it tilts toward or away from the West. For now, the reformist policy of conciliation with America is holding sway. Iran’s foreign minister has publicly disowned the Badr Brigades, for instance. But if the hard-liners feel threatened by Washington, say experts, they may encourage a Shiite insurgency in Iraq–and a lot more embassy seiges.