A US F-35 stealth jet has reportedly lost a panel while flying a routine training mission off the coast of the Japanese island of Okinawa.
A 1lb panel is said to have fallen off an F-35A at around 10.30am on Thursday morning, measuring 12 x 24 inches.
A statement from 18th Wing, based at the nearby Kadena Air Base, reported in various media outlets, says the panel was "most likely lost over the ocean".
Photographs of the reported incident have been shared in Japan across social media
It said the pilot's wingman noticed the problem as the jet prepared to land, with a post-flight inspection subsequently confirming that the part was missing.
12 US Air Force F-35As and around 300 airmen arrived in Okinawa in November for the aircraft's first operational deployment to the Indo-Asia-Pacific region.
Although Air Force officials have so far declined to discuss the nature of the training being carried out during the incident, photographs have been released of the aircraft training alongside Japanese Air Self Defense Force F-15 Eagles.
It comes after local protests began on Okinawa against the safety and noise of US military aircraft.
The development of the F-35 fifth-generation fighter, which is the most expensive military weapons system in history, has faced criticism in recent years.
US Senator John McCain said last year it had "been both a scandal and a tragedy with respect to cost, schedule and performance".
Britain, meanwhile, is reportedly facing 'hundreds of millions of pounds in hidden costs', having ordered 138 of the aircraft.
Forces Network has contacted the US Air Force for comment.
Photographs show US F-35A aircraft training alongside Japanese F-15 Eagles earlier this week.