The explosion of violence in Iraq sparked by the U.S. move to crack down on Moqtada Sadr and his militia offers both opportunity and danger for neighboring Iran and could undermine the growing secular, democratic movement there.

Reports are emerging claiming - predictably but probably not inaccurately - that Sadr, the firebrand young 31-year-old Iranian cleric and his Mahdi Army have been strongly supported both financially and with weapons by Iran's Revolutionary Guard and the southern Lebanon-based Shiite Hezbollah with which the Guards are closely allied.

A former Iranian intelligence officer identified only as "Hajj Saeedi" told the London based Al-Sharq al-Aswat newspaper in an interview published April 3 that, before the latest uprising, Iran had successfully infiltrated hundreds of agents from its religious movement, the Pasdaran, into Iraq through Kurdish areas. Saeedi also claimed that Iran was subsidizing underground operations in Iraq "to the tune of $70 million a month," the paper said.

And last Wednesday, The Washington Times cited U.S. "military sources with access to recent intelligence reports "as saying that Sadr was "being supported by Iran and its terror surrogate Hezbollah." Sadr "has traveled to Iran and met with its hard-line Shiite clerics," the paper said. It reported that according to U.S. military sources, Sadr was also "being aided directly by Iran's Revolutionary Guard.

Given Sadr's fierce and unrelenting anti-American position, and the Revolutionary Guards long history of extremely close and highly successful cooperation with Hezbollah in southern Lebanon, such a relationship appears extremely likely. But there is much more to the story than that.

First, the Iranian hardliners, including the Revolutionary Guards and their leading supporters, Supreme Guide Ali Khamenei and former President Ali-Akbar Hashemi Rafsanjani, have often been at odds, and occasionally have been reined in by more cautious forces led by President Mohammed Khatami.

Khatami, and his more cautious pragmatists -- it may be misleading to call them moderate -- were very much in the saddle during and after the three-week conquest of Iraq by U.S. and allied forces a year ago. American military prowess was so overwhelming that Iranian leaders, as they discussed in their own media, were genuinely alarmed that U.S. leaders, boosted by their easy success, would turn on them next.

Since then, public Iranian diplomacy has been and so far continues to be highly cautious towards the United States while seeking closer ties with the European Union. Indeed, on Tuesday, International Atomic Energy Agency chief Mohammed el-Baradei announced in Tehran that Iran had agreed to a timetable for international inspections of its nuclear facilities.

This was a diplomatic coup for Britain, Germany and France. All three nations have urged Iran to accept such a deal and Tehran has taken their calls seriously. For Iranian leaders appear to regard continued warm and stable ties with major European nations as a crucial diplomatic defense against being attacked by the United States.

Also, Tehran has been working closely with Grand Ayatollah Ali Sistani, the Iranian-born religious leader of Iraq's Shiites, who comprise 65 percent of the total population. And Sistani, like the Tehran government, has been cautiously following a policy of dealing with the United States and the CPA, while taking independent stands, but so far avoiding any direct clashes.

However, in recent weeks, there have been signs that more aggressive elements have been on the rise in Tehran's governing circles regarding Iraq. The main reason for this, Middle East diplomatic sources said, was Iran's concern -- and anger -- over its leaders' belief that hundreds of millions of dollars was already flowing in business kickbacks to Ahmed Chalabi, head of the Iraqi National Congress and that this money was expected to be used to fund efforts to spread democracy - American style - in Iran itself and destabilize the structure of the Islamic Republic there.

However, amid these swirling murky waters of claim and counter-claim, it appears clear that the drama of events within Iraq itself is the central dynamic driving events. Sadr's Mahdi Army only rose up after U.S. forces directed by Coalition Provisional Authority chief administrator L. Paul Bremer sought to close his newspaper and crack down on him.

As UPI reported last week, top civilian policymakers in the Pentagon did not take Sadr seriously, even if they were aware of the claims of Iranian support that The Washington Times and Al-Sharq al-Aswat have reported.

The scale of the Sadr uprising and the enthusiasm with which Sunni Islamist guerrillas have made common cause certainly took the Bush Administration totally by surprise. It has been an article of faith in White House and Pentagon civilian circles that Sadr's Shiite extremists in southern Iraq and the Sunni ones in central Iraq would never work together.

But they have. And the fact should not have come as a surprise at all. For the Shiite Hezbollah in Southern Lebanon has long enjoyed excellent relations with the Sunni Islamic Jihad and Hamas in their fierce intifada campaigns against Israel.

Far from cynically, secretly and single-mindedly building up Sadr and his Mahdi Army, Iran has followed a complex and generally cautious multi-pronged policy towards Iraq and its U.S. occupiers over the past year.

 The real danger for the overstretched and undermanned U.S. forces now facing major risings throughout the center and south of Iraq is that Iran may be propelled into a far more confrontational and unified position that could lead to a direct clash or even full-scale war with the United States.

That could happen if the current uprising does spectacularly well, which does not at the moment appear likely. However, a much more likely and potentially more dangerous scenario would be if U.S. forces kill Sadr and he then becomes a charismatic martyr figure among Shiite believers, whose religious culture has also thrived on such symbolism of heroic sacrifice and suffering. Then events could really get out of control on all sides.

Martin Sieff is chief news analyst for United Press International.  This adapted piece is used with the permission of UPI.