Updated 6:21 pm

Iran probably did scoop up one of America’s stealthy RQ-170 Sentinel spy drones after the bat-winged aircraft crashed near the Iran-Afghanistan border last week. Multiple news outletshave cited anonymous U.S. government sources confirming Tehran’s claims that it’s in possession of the radar-evading Unmanned Aerial Vehicle.

What’s still uncertain is exactly why the drone went down, what it was doing in or near Iranian airspace and who was operating it. The Iranians claim they captured the RQ-170 “with little damage” after an electronic-warfare unit jammed its control signal. But the RQ-170, like most modern drones, doesn’t need orders from its human operators to stay in the air.

Escalating tension over Iran’s alleged nuclear-weapons program could explain the stealthy ‘bot’s presence over the border, but less clear is who programmed the drone’s mission. We know the U.S. Air Force operates the hush-hush RQ-170s — the flying branch has admitted as much. But sources told ABC News that the crashed Sentinel was a CIA asset.

It’s not unheard of for the Air Force and CIA to share equipment. Both agencies fly identical Predator drones. Its also not unheard of to have military pilots fly drones under the CIA’s operational control.

The RQ-170, built in small numbers by Lockheed Martin sometime in the last decade, is apparently moderately stealthy by virtue of its shape and radar-absorbing coating. “The RQ-170 will directly support combatant commander needs for intelligence, surveillance and reconnaissance to locate targets,” the Air Force explained in 2009, two years after photographers first spotted the drone at Kandahar Air Field in southern Afghanistan.

The Sentinel reportedly streamed video to commanders during the May raid to kill Osama Bin Laden in Pakistan. The apparently Cessna-size UAV has also been spotted at U.S. bases in South Korea and Japan, leading to speculation that it’s involved in sniffing out nuclear facilities.

That’s probably what the RQ-170 was doing over Iran. The U.S. and Israel have threatened air strikes against Tehran’s nuclear weapons program; any bombing campaign would begin with aerial surveillance of potential targets.

In light of the threats, Iran has been reinforcing its defenses. Six weeks ago Russia announced it had transferred to Iran a ground-based electronic intelligence and jamming system known as “Avtobaza.” Stephen Trimble at Flightglobal speculates that the Avtobaza could be used to interfere with a drone’s electronics and cause it to crash. Last week NATO issued a press release claiming operators “lost control” of an unspecified UAV in western Afghanistan.

Like just about every spy drone operating today, the RQ-170 can follow GPS waypoints, instead of being steered by a remote operator. And when drones like the Sentinel loses radio or satellite contact with their human overlords, they are usually programmed to do something reasonable, ranging from circling until contact is resumed to continuing with the mission autonomously to flying home. Moreover, Pentagon spokesman Capt. John Kirby told reporters there was no indication the Sentinel was brought down by “hostile activity of any kind.”

It’s possible the RQ-170 malfunctioned and crashed, either in Iranian territory or close enough to Iran that Tehran’s forces could dart across the border to seize the wreckage. In any event, the Iranians might not learn much — just as the Chinese stand to gain little from examining the remains of a stealthy U.S. helicopter lost during the Bin Laden raid. The principles of stealth shaping are well-understood worldwide, and any stealth coating on the Sentinel reflects decade-old technology.

Similarly, the RQ-170?s sensors are “already dated,” according to Aviation Week. The Sentinel is advanced enough to pull off some risky spy missions for the military and CIA, but not so advanced that losing one is a national emergency.

Photo: Via Combat Aircraft