Iran’s purported reverse-engineered copies of the Lockheed Martin RQ-170 Sentinel unmanned aircraft are nothing but cheap mockups, industry sources told USNI News.

The Iranian state-owned Fars News Agency reported that the Islamic Revolution Guards Corps (IRGC) showed off a modified version of the stealthy RQ-170 at an aerospace exhibition in Tehran on Sunday.

However, unlike the original U.S. version of the aircraft, the Iranians claim their version of the Sentinel is armed—and designed to engage U.S. Navy warships at sea. Sources with knowledge of the RQ-170 design dismissed the Iranian copy as a crude mockup.

“It seems their fiberglass work has improved a lot. It also seems that if it were a functional copy, versus a detailed replica, it wouldn’t necessarily have the exact same landing gear, tires, etc,” said one source with familiar with the RQ-170.

“They would probably just use whatever extra F-5 parts or general aviation parts they had lying around.”

The Iranians based their mockup on an RQ-170 that had crashed inside that country on Dec. 4, 2011, during a Central Intelligence Agency intelligence-gathering mission. Shortly after the crash, U.S. President Barack Obama asked the Iranians to return the stricken aircraft. “We’ve asked for it back. We’ll see how the Iranians respond,” Obama said at the time.

Iran had claimed that their military forces had brought the RQ-170 down via a cyber attack, however U.S. officials said at the time that they lost communications with the aircraft causing it to crash.

Later, at least one U.S. source suggested that the Iranian version of events might not be entirely inaccurate. The source said that there were indications that the Iranian may have been able to interrupt the RQ-170’s data-link and bring it to a soft landing.