WASHINGTON — U.S. intelligence officials, already focused on Iran's potential for building nuclear weapons, are struggling to solve a more immediate mystery: the murky relationship between the new Tehran leadership and the contingent of Al Qaeda leaders residing in the country.
Some officials, citing evidence from highly classified satellite feeds and electronic eavesdropping, believe the Iranian regime is playing host to much of Al Qaeda's remaining brain trust and allowing the senior operatives freedom to communicate and help plan the terrorist network's operations.
And they suggest that recently elected President Mahmoud Ahmadinejad may be forging an alliance with Al Qaeda operatives as a way to expand Iran's influence or, at a minimum, that he is looking the other way as Al Qaeda leaders in his country collaborate with their counterparts elsewhere.
"Iran is becoming more and more radicalized and more willing to turn a blind eye to the Al Qaeda presence there," a U.S. counter-terrorism official said.
The accusations from U.S. officials about Iranian nuclear ambitions and ties to Al Qaeda echo charges that Bush administration figures made about Iraq in the run-up to the U.S.-led invasion three years ago.
Those charges about Iraq have been discredited. And in the case of Iran, some intelligence officials and analysts are unconvinced that Al Qaeda operatives are being allowed to plot terrorist acts. If anything, they suggest, the escalating tensions between Shiite and Sunni Muslims in Iraq would logically cause Iran's Shiite government to crack down on Al Qaeda, whose Sunni leadership has denounced Shiites as infidels.
A U.S. intelligence official said he did not see any relaxation in Iran's restrictions on Al Qaeda members.
"I'm not getting the sense that these people are free to roam, free to plot," the official said.
Still, the official acknowledged that the relationship between Tehran and Al Qaeda officials within Iran was largely unknown to U.S. and allied intelligence, especially since Ahmadinejad's election last summer.
To some U.S. intelligence officials, what worries them most is what they don't know.
"I don't need to exaggerate the difficulty in determining what these people are up to at any given moment," the intelligence official said.
The U.S. counter-terrorism official was more blunt. "We don't have any intelligence going on in Iran. No people on the ground," he said. "It blows me away the lack of intelligence that's out there."
U.S., European and Arab intelligence officials spoke on condition of anonymity because they were not authorized to discuss the issues publicly.
Ties between Iran and Al Qaeda were highlighted by the Sept. 11 commission, which disclosed a wealth of details about such connections in its final report. The commission said Iran and Al Qaeda had worked together sporadically throughout the 1990s, trading secrets, including some related to making explosives.
Iranian representatives to the United Nations did not return repeated phone calls seeking comment.
In November, the State Department's third-ranking official, Undersecretary R. Nicholas Burns, said the U.S. believed "that some Al Qaeda members and those from like-minded extremist groups continue to use Iran as a safe haven and as a hub to facilitate their operations."
A year ago, Iranian delegates to a global counter-terrorism conference circulated a document describing Iran as "a major victim of terrorism." The document blamed links between drug trafficking and terrorism for "thousands of security problems," especially along Iran's eastern border with Afghanistan and Pakistan.
Al Qaeda operatives and family members have lived in Iran for years, many since late 2001, when they fled the U.S.-led bombing of Afghanistan. Many other Al Qaeda figures fled to Pakistan -- a U.S. ally -- and are believed to be there still.
Four months ago, Iran declared that no Al Qaeda members remained in the country, but U.S. officials reject the claim. At other times, Iranian officials said that Al Qaeda members were kept under house arrest and their activities monitored.
In Tehran, analysts said American officials were misreading Iran's intentions. The fact that the government has not heeded U.S. demands to turn over Al Qaeda suspects should come as no surprise given the state of relations between the two countries, said Nasser Hadian, a political analyst at Tehran University.
"They won't. Why should they" without receiving something in return? he said.
Some of the suspects have been indicted in the United States in connection with terrorist attacks, including the 1998 bombings of two U.S. embassies in East Africa, but Iran has refused to extradite them.