WASHINGTON // A US drone was flying deep inside Iranian airspace when it was brought down by the country's armed forces, state media reported yesterday.
The stealth version of the RQ-170 unmanned aircraft was detected over the eastern town of Kashmar, 225 kilometres from the border with Afghanistan, state radio reported yesterday.
The report did not speculate as to why the drone flew over the town, located in an agricultural area known for carpets and saffron.
The report added that Iran will "soon" broadcast video footage of the downed drone.
Iran first reported the downing of the aircraft on Sunday but did not say when the incident happened. US officials say the drone crashed over the weekend. They say it had spied on Iran for years from a US airbase in Afghanistan.
The drone was programmed to automatically return to base even if its data link was lost. US officials say the drone probably malfunctioned and was not downed by Iranian electronic warfare.
US officials have been tight-lipped about Iranian claims that its military downed the RQ-170, a radar-evading, wedge-shaped aircraft dubbed "the Beast of Kandahar" after its initial sighting in southern Afghanistan.
The US-led Nato mission in Afghanistan said the Iranians might be referring to an unarmed reconnaissance aircraft that disappeared on a flight in western Afghanistan late last week. But they declined to say what type of drone was involved.
A US government source said the plane was on a CIA mission.
The incident came at a time of rising tensions between Iran and the West over Tehran's nuclear programme. The US and other western nations tightened sanctions on Iran last week and Britain withdrew its diplomatic staff from Tehran after hard-line youths stormed two diplomatic compounds.
The US has not ruled out military action against Iran's nuclear facilities if diplomacy fails to resolve a dispute over the programme, which Washington believes is aimed at developing atomic weapons.
The RQ-170 Sentinel, built by Lockheed Martin, was first acknowledged by the US air force in December 2009. It has a full-motion video sensor that was used this year by US intelligence to monitor Osama bin Laden's compound in Pakistan ahead of the raid that killed him.
Former and current military officials familiar with the Sentinel said they were sceptical about Iranian media reports that Iran's military brought down one of the drones in eastern Iran, especially since Tehran has not released any pictures of the plane.
The aircraft is flown remotely by pilots based in the US, but is also programmed to fly back to the base it departed from if its data link with those pilots is lost, according to the defence analyst Loren Thompson, who is a consultant for Lockheed and other companies.
Other unmanned aircraft have a similar capability, including the General Atomics Predator drone, industry sources said.
The fact that the plane did not return to its base suggests a "catastrophic" technical malfunction, agreed one industry executive familiar with the operation and programming of unmanned aerial vehicles.
US officials say they always worry about the possibility of sensitive military technologies falling into the hands of other countries or terrorist groups, one reason US forces destroyed a stealth helicopter that was damaged during the bin Laden raid in Pakistan.
Many classified weapons systems have self-destruction capabilities that can be activated if they fall into enemy hands but it was not clear if that was the case this time.
The design of the plane and the fact that it had special coatings that made it nearly invisible to radar were already well documented. If it survived a crash, all on-board computer equipment was heavily encrypted.
Lockheed confirmed that it makes the RQ-170 drone, which came out of its secretive Skunk Works facility in southern California, but referred all questions about the incident to the air force. Mr Thompson and several current and former defence officials said they doubted Iranian claims to have shot the aircraft down because of its stealth features and ability to operate at relatively high altitudes.
Iran was also unlikely to have jammed its flight controls because the system is highly encrypted and uses a direct uplink to a US satellite, they said.
"The US air force has experienced declining attrition rates with most of its unmanned aircraft. However, this is a relatively new aircraft and there aren't many in the fleet, which means that malfunctions and mistakes are more likely to occur," Mr Thompson said.
One ex-defence official said he "absolutely" agreed that the aircraft was not lost because of action by Iran.
