But experts suggested that even if the Iranians have found parts of the unmanned spy plane, they can probably glean little from it. Because it likely fell from a high altitude, there may be very few large pieces to examine.
The RQ-170 - known as the Sentinel - has been used in Afghanistan, particularly along the border, for several years. The U.S. Air Force has just "a handful" of them, said defense analyst Loren Thompson, with the Virginia-based Lexington Institute.
"I think we're always concerned when there's an aircraft, whether it's manned or unmanned, that we lose, particularly in a place where we're not able to get to it," Navy Capt. John Kirby, a Pentagon spokesman, told reporters Monday.
U.S. officials have acknowledged that the military lost control of one of the stealthy drones while it was flying a mission over western Afghanistan. Iran's official IRNA news agency has said that Iran's armed forces shot it down.
U.S. officials have rejected that claim, saying there are no indications the Sentinel was shot down. In either case, officials said this would be the first Sentinel lost by the U.S.
Analysts, however, played down any serious impact of the drone - or pieces of it - falling into Iranian hands.
"This is an aircraft that evades radar because of its shape and because of the special material used," said Thompson. "It won't enable the Iranians to build a stealthy unmanned aircraft."
Analysts said that stealth technologies - primarily the low-observable shape and the materials used - are fairly well known, but often hard to replicate. The Sentinel, made by Lockheed Martin, has a swept-wing shape, much like the B-2 stealth bomber. And it's been called the "Beast of Kandahar" because of its use in Afghanistan.
"They were designed to be silver bullets that could go places that other manned or unmanned aircraft would not be able to go. It specifically is designed to be very difficult for enemies to track and target," said Thompson. "This is a high-flying unmanned aircraft that malfunctioned and then fell to earth. It's likely to be broken up into hundreds of pieces."
John Pike of the Globalsecurity.org think tank said the Iranians already have all the data on the drone's external shape, "and there is nothing particularly unique about this configuration."
He said the key to America's success with the stealthy aircraft is the fuel efficient engines, which give it the ability to stay aloft for days rather than hours.
"Are we going to stop flying them? No. Was it a secret we were flying them? No," said Pike. "Did Iran shoot it down? Probably not. Because Iranian air defenses are not very good, and it is a good stealth vehicle. And did Iranian hackers hack into it and bring it down? No. It's just too hard to do."
The Sentinel gained notoriety earlier this year when officials disclosed that one was used to keep watch on Osama bin Laden's compound in Pakistan as the raid that killed him was taking place.
Associated Press broadcast reporter Sagar Meghani contributed to this report.