A U.S. State Department spokesman says there is no hard evidence of any Iranian role in the unrest in Iraq. But, there is considerable difference among U.S. officials about Tehran's involvement in Iraq.
Asked about possible Iranian involvement in the Shi'ite uprising in Iraq, State Department spokesman Adam Ereli said there is no confirmation of any such reports.
"I think we've seen, generally speaking, reports of, suggestions of, Iranian involvement, collusion, provocation, coordination, etc, etc.," he said. "But I think there's a dearth of hard facts to back these things up."
That view is at odds with Defense Secretary Donald Rumsfeld, who said Wednesday that Iran was interfering in Iraq.
"We know the Iranians have been meddling [in Iraq] and it is unhelpful to have neighboring countries meddling in the affairs of Iraq, and I think the Iraqi people are not going to want to be dominated by a neighboring country, any neighboring country," he said.
Those two views underscore the sharp differences of opinion among analysts on Iraqi and Iranian affairs both inside and outside the U.S. government.
The issue of Iranian involvement, if there is any, arose because of the leading role played by Shiite cleric Moqtada al-Sadr in the uprising.
Alireza Noorizadeh, head of the Center for Arab-Iranian Studies in London, says at least some segments of the Iranian government are actively supporting the rebellion.
"I just give you one example: the Iranians provided Sadr's followers with 800 Thuriya satellite telephones, as well as other equipment, [that] they are using to communicate with each other. Their involvement is huge.
He says Revolutionary Guard and intelligence units loyal to Iran's spiritual leader Ayatollah Ali Khamenei are backing Mr. Al-Sadr in defiance of President Mohammad Khatemi.
But Rueul Gerecht, a former CIA Middle East officer now with the Heritage Foundation, is skeptical of wide-scale Iranian involvement.
"I've heard people talk of thousands of official Iranians of some agency or bureau running around the country," he said. "I think that's a bit much. I think there are a substantial number. They are no doubt up to no good. But it's very difficult to know for sure whether they have developed some game plan against the United States and against Iraqis who would be working with the United States."
Mr. Gerecht says that, even if Iran is involved, he is doubtful that there is some kind of master plan at work.
"The Iranians could be, you know, just sort of fishing, throwing out to see what they can collect, and spreading support around and hoping for the best," he said. "I am skeptical as to whether they've developed any sort of master plan for disemboweling the United States in Iraq."
Iran is overwhelmingly Shi'ite Muslim. Shi'ites are also a majority in Iraq, where they suffered repression at the hands of Saddam Hussein and a Sunni Muslim minority. Iran and Iraq fought a bloody eight-year-long war in the 1980s in which upwards of one million people are believed to have died. The final prisoner of war exchange took place only last year.