Shortly after the U.S. invaded Afghanistan in late 2001, al Qaeda's central leadership broke into two groups. U.S. intelligence believes that one group, headed by Osama bin Laden and Ayman al Zawahiri, fled to the east to find safe haven in Pakistan's tribal areas. The second group, headed by an Egyptian named Saif al Adel, went west to Iran. This second group, which intelligence analysts say includes al Qaeda's management council, or "shura," includes about two dozen militants, including Adel, al Qaeda spokesman Suliman abu Ghaith and some of bin Laden's relatives, including two of his sons, Saad and Hamza.
Although U.S. officials rarely talk publicly about them, these militants are considered to be among the most dangerous terrorists in the world. Adel is on the FBI list of Most Wanted Terrorists and is a suspect in the 1998 bombings of the U.S. embassies in Kenya and Tanzania. The State Department has put a $5 million bounty on his head through the Rewards for Justice program; the only al Qaeda figures with higher bounties are Osama bin Laden and his deputy, Zawahiri.
Iranian authorities detained these militants in 2003, and they have been under what one U.S. official called "loose house arrest" in Iran ever since. The U.S. government quietly sent messages to Iran through the Swiss government, requesting that the al Qaeda figures be turned over to their native countries for interrogation and trial. Iran has refused.
In the past, the Iranians have also resisted efforts by al Qaeda to get the militants released. But recently there has been a renewed effort by al Qaeda to negotiate for their release and signs that the Iranians are willing to at least talk about that.
"Al Qaeda would like to get those folks a deal and they've been trying to work a deal," a senior defense official tells ABC News. "Right now there is greater effort being applied by al Qaeda to seek a resolution." Although Iran has recently signaled a willingness to discuss the issue, this official says, "I don't see the Iranian government desiring to work very fast or quickly on that. "
Buried inside the latest State Department report on terrorism, released in April, is one of the few on-the-record statements on this issue by the U.S. government.
"Iran has repeatedly resisted numerous calls to transfer custody of its AQ detainees to their countries of origin or third countries for interrogations or trial," the report says. "Iran also continued to fail to control the activities of some AQ members who fled to Iran following the fall of the Taliban regime in Afghanistan."
But U.S. officials tell ABC News that one reason they have not raised the issue more publicly is that they believe Iran has largely kept these al Qaeda operatives under control since 2003, limiting their ability to travel and communicate.
"It's been a status quo that leaves these people, some of whom are quite important, essentially on ice," said a U.S. official.
Iran has its own reasons to keep these militants under house arrest. Al Qaeda is a Sunni Muslim group that has a complicated, sometimes tense, relationship with Iran. Recent public statements by al Qaeda have taken an unusually anti-Iranian tone. In two audiotapes released last month, for example, Zawahiri lambastes the Iranian government for, among other things, trying to take over southern Iraq.