WASHINGTON -- The stealth CIA drone that crashed deep inside Iran was part of stepped-up surveillance that has frequently sent the most hard-to-detect U.S. drone into the country to map suspected nuclear sites, according to foreign officials and U.S. experts briefed on the effort.
Until last week, the high-altitude flights from Afghanistan bases were among the most secret of many intelligence-collection efforts against Iran, and U.S. officials refuse to discuss it. But the crash, which Iranian officials said occurred more than 140 miles from Afghanistan's border, blew the program's cover.
The overflights by the bat-winged RQ-170 Sentinel, built by Lockheed Martin and first glimpsed on a Kandahar, Afghanistan, airfield in 2009, are part of an increasingly aggressive intelligence program aimed at Iran, current and former officials say. The effort's urgency has been underscored by a recent debate in Israel about whether time is running out for a military strike to slow Iran's progress toward a nuclear weapon.
President Obama's national security adviser, Tom Donilon, hinted at secret U.S. efforts to watch Iran's nuclear program. "We will continue to be vigilant," he said last month at the Brookings Institution. "We will work aggressively to detect any new nuclear-related efforts by Iran."
CIA use of drones over Iran reflects a growing belief in the Obama Administration that covert action and choreographed economic pressure may be the only way to get Iran to abandon nuclear ambitions, U.S. officials say.
The U.S. shift toward more confrontation -- one that includes more arms sales to Iran's potential rivals and bellicose remarks by U.S. officials and allies -- suggests growing pessimism about prospects for dialogue, officials say.
This evolving strategy includes more use of remote-controlled stealth aircraft, such as the one that came down in Iran, and other covert efforts, say U.S. officials and Western diplomats who spoke on condition of anonymity.
The U.S. officials said the drone was in a fleet of secret aircraft the CIA has used for years in an escalating espionage campaign targeting Iran's nuclear facilities. As efforts surged, the White House boosted sales of bunker-busting munitions, fighter jets, and other armaments to Persian Gulf states and Israel, building on efforts to boost the power of U.S. allies in the region, officials say.
Iran said last weekend it had recovered the RQ-170, the same drone deployed over Osama bin Laden's compound before he was killed in May. Intelligence officials were disturbed the drone was publicly discussed in the coverage of the bin Laden raid, fearing exposure of its use over Iran.
A statement from the U.S.-led International Security Assistance Force in Afghanistan said Iran might have recovered an "unarmed reconnaissance aircraft" lost while "flying a mission over western Afghanistan." But experts noted the RQ-170's technology -- which greatly reduces the chances it can be detected by radar -- had little use in western Afghanistan; the Taliban have no radar to detect flights.
Iranian officials have said the craft was detected near Kashmar and that it was shot down or crashed because the Iranian military hacked its control systems. U.S. officials call those stories fanciful and say a malfunction caused the drone's loss.
Either way, the centerpiece of what had been a covert program is in the hands of Iranian forces, which may share the captured technology with other nations. Accounts of the extent of damage to the craft differ.
Iran displayed the first images of what is described as the captive aircraft on state TV Thursday. The 2.5-minute video was the first visual evidence Iran had the drone. It looked to be in good shape, which would seem inconsistent with an uncontrolled landing, although closer inspection of the images appeared to reveal a taped fracture on part of the wing.
John Pike, chief of consulting firm GlobalSecurity.org, said in response to a CNN query that the aircraft did not look the way he would expect after a crash, fueling suspicion the Iranians may have displayed a mock-up. Other aviation experts said the vehicle in the video appeared authentic.
Two officials said the United States considered going in to retrieve the drone or to destroy it, as reported Wednesday by the Wall Street Journal, but the operation was deemed too risky. There are questions of whether Iran could reverse-engineer the technology, though they could sell the craft to China, Russia, or other nations. "The flights from Moscow and Beijing to Tehran were probably quite full the last few days," said P.W. Singer, who studies military robotics at the Brookings Institution. He said the most sought-after technology on the craft is probably its array of sensors, which may include sophisticated radar more advanced than anything Russia or China uses.
Dennis Gormley, a University of Pittsburgh missile-and-drone expert, said reverse-engineering the craft will be tough. "In any complex piece of aviation equipment, you have to replicate the tolerances precisely."
In Abbottabad, Pakistan, the RQ-170 was used to model the bin Laden compound. In Iran, among other missions, it was looking for tunnels, underground facilities, or other sites where Iran could be building centrifuge parts or enrichment facilities. One such site, outside Qom, was revealed by Mr. Obama and the leaders of France and Britain in 2009, though it appears Israel played a major role in detecting it.
Surveillance of Iran is nothing new: U.S. satellites have been trained on its nuclear facilities, missile bases, and defenses for many years. But the RQ-170, which can fly at 50,000 feet altitude, is thought vital to the effort.
While an orbiting surveillance satellite can observe a location for only a few minutes at a time, a drone can loiter for hours, sending a video feed as people move about. Such a "pattern of life," as it is called, can give crucial clues to the nature of the work being done, the equipment used, and the size of the work force.
Experts say the drone almost certainly carries communications intercept equipment and sensors that can detect tiny amounts of radioactive isotopes and other chemicals that can give away nuclear research.
News reports in South Korea in 2009 said the United States planned to base the RQ-170 drone there to fly surveillance missions over North Korea, whose nuclear and missile programs are a top U.S. intelligence target.