A Japanese air force F-35 stealth fighter has crashed into the Pacific Ocean during a night training flight, the country's defence ministry said.
The disappeared from radar while flying off the eastern coast of Aomori and parts of the jet were found late on Tuesday, the Air Self-Defence Force said.
The pilot is still missing.
The jet went missing about half an hour after taking off from the Misawa air base with three other F-35As for anti-fighter battle training.
Japanese defence minister Takeshi Iwaya told reporters the cause of the disappearance is not immediately known.
He said 12 other F-35s at the Misawa base would be grounded.
The F-35 family of jets are the first to combine radar-evading stealth technology with supersonic speeds and the ability to conduct short take-offs and vertical landings.
The remaining 12 other F-35s at the Misawa base will be grounded, following the incident. Source: AAP
The aircraft has the ability to operate from land and sea.
Japan started deploying the expensive US-made F-35s since last year, part of its plan to bolster its defence spending and weapons capability in the coming years to counter potential threats from North Korea and China.
Under guidelines approved in December, Prime Minister Shinzo Abe's government plans to buy 147 F-35s, including 105 F-35As, costing about 10 billion yen ($A126 million) each.
