The Japanese Air Self-Defense Force said an F-35 fighter jet deployed at Misawa Air Base in northeastern Japan disappeared during training on Tuesday.
The aircraft was flying with three other planes off the coast of Aomori Prefecture, some 135 kilometers east of the base when radar contact was lost about 7:27 p.m., it added.
According to local media reports, the jet took off with several other aircraft from the base about half an hour before the disappearance.
The aircraft is believed to have one pilot on board.
A search and rescue operation is already underway. The Japanese Coast Guard has deployed two patrol ships to look for the aircraft and the pilot.
The jet has been deployed at the base since January 2018. Japan’s Ministry of Defense currently has plans to deploy a total of 42 aircraft to the base.
In February, a Japanese F-2 fighter jet crashed into the Sea of Japan about 130 kilometers from its air base in Fukuoka, but the two crew members were recovered successfully by rescue teams.
Last September, the US military grounded half of its entire fleet of F-35 aircraft following a crash in South Carolina. The previous year, an F-35 deployed in Japan lost part of its fuselage mid-flight during a routine training mission.