An F-35A Lightning II stealth fighter returned to Kadena Air Base, Okinawa, on Dec. 18, 2023, missing a panel from the body of the aircraft. (Satoru Kuba)

CAMP FOSTER, Okinawa – An advanced stealth fighter that returned to its base on Okinawa missing a panel this week may have lost the part over the ocean, according to an Air Force spokesman.

The F-35A Lightning II, assigned to the 356th Fighter Squadron, landed at Kadena Air Base at 10:24 a.m. Monday, Okinawa Times reported the following day.

The aircraft was missing a hexagonal side panel measuring 18 by 12 inches and weighing approximately two pounds, according to an email Tuesday from 18th Wing spokesman 1st Lt. Robert Dabbs. The panel is located below the cockpit, on the right side of the aircraft.

“Expectations are the panel departed the aircraft over water,” Dabbs said. “We have not received reports of damage or injuries.”

The 18^th Wing is investigating, Dabbs said. The wing remains equally committed to flight safety and rigorous training, he added.

The Lightning II took off sometime in the morning for training, Okinawa Times said.

The missing panel covers external ports for electronic devices, the paper said. The aircraft can lose its stealth ability without the piece.

The Okinawa Defense Bureau, which represents Japan’s Defense Ministry on the island, strongly urged the U.S. military to prevent future mishaps, a spokesman told Stars and Stripes by phone Tuesday evening.

“Ensuring safety is a major requirement for the operation of U.S. military aircraft and we will continue to request that the U.S. side takes all possible precautions,” he said.

Some government officials in Japan may speak to the media only on condition of anonymity.

The bureau on Tuesday notified Okinawa prefecture of the incident, a spokeswoman from Okinawa prefecture’s Military Base Affairs Division said by phone that day. The division is awaiting further details and considering a protest to the U.S. military.

The F-35 is on a rotational deployment to Okinawa from Eielson Air Force Base, Alaska. The aircraft is one of the temporary replacements for 48 aging F-15C/D fighters, previously stationed at Kadena, until a permanent solution is found.

The people of Okinawa are sensitive to reports of aircraft crashes and falling parts following several high-profile incidents in years past.

A Marine Corps CH-53D Sea Stallion crashed Aug. 13, 2004, onto the Ginowan campus of Okinawa International University, injuring three crew members.

In December 2017, a window fell from a Marine Corps CH-53E Super Stallion helicopter and landed on an elementary school sports field near Marine Corps Air Station Futenma’s fence line in Ginowan. About 40 children were playing nearby at the time. One boy received a minor injury from a stone thrown up by the falling window.

Four years later, a steel shipping container inexplicably fell from a Marine CH-53E Super Stallion helicopter into the sea.