BAGHDAD — Among the myriad military and intelligence agencies that make up Iran's security forces, none has the skill and reach of the Quds Force, an elite unit nominally within the command structure of the Iranian Revolutionary Guard Corps.
Like the Revolutionary Guard, the Quds Force and its predecessors were among the semiofficial militias, charities and centers of clerical power born of the paranoia and zeal of the tumultuous years after Iran's 1979 Islamic Revolution, which brought Ayatollah Ruhollah Khomeini to power.
Originally, the Revolutionary Guard played a defensive role. In the 1980s, Iran's Shiite revolutionaries faced a war against Iraq as well as the hostility of Iranian secular nationalists, the West and Sunni-dominated regimes of the Middle East.
The Revolutionary Guard was entrusted to protect Khomeini's theocracy. But the revolutionaries also were inspired to spread their vision abroad.
The Quds Force and its predecessors consisted of the Guard's most skilled warriors. Experts said they were highly secretive commando units sent abroad to help Shiites usurp monarchies in the Persian Gulf, gun down enemies and battle Israeli forces in southern Lebanon. They also reportedly have run operations in Sudan, South Asia and Western Europe.
Their plans sometimes coincided with U.S. interests, as when they supported Afghans fighting the Soviet Union in the 1980s and Bosnian Muslims battling Serbs in the 1990s.
The Quds Force also has been involved in Iraq. It assisted Kurdish rebels fighting Saddam Hussein in the 1980s and Shiites battling his regime in the 1990s. Even Ahmad Chalabi's expatriate Iraqi National Congress had Quds Force help, experts say.
At most, the force numbers 2,000, said Mahan Abedin, director of research at the Center for the Study of Terrorism, a London think tank.
"It's a remarkably efficient organization, quite possibly one of the best special forces units in the world," he said.
The extent to which the Quds Force is controlled by the government has been hotly debated in U.S. foreign policy circles.
"This has been a topic of debate among Iran experts inside and outside the government for 25 years," said Kenneth M. Pollack, an Iran expert at the Brookings Institution's Saban Center for Middle East Policy. "There are people who believe the Quds Force does not move a muscle without getting explicit orders from [supreme leader Ayatollah Ali] Khamenei; there are other people who believe they are rogues. The weight of evidence is somewhere in the middle."