Japan's Defense Ministry is thinking of raising an Air Self-Defense Force stealth fighter, which crashed off northern Japan, once it has been found.
The F-35 went down in the waters off Aomori Prefecture last Tuesday.
One week after the accident, the SDF and US forces are still conducting an air and sea search.
The pilot remains missing, and most parts of the stealth fighter have yet to be found.
Air SDF officials say the F-35 sent an "aborting practice" message about half an hour after it took off from the SDF's Misawa base in Aomori Prefecture. The plane disappeared from radar about a minute later.
The Air SDF says the aircraft may have crashed shortly after the pilot noticed signs of trouble. Details surrounding the incident remain unknown. It may take time to establish the cause of the crash.
The F-35 is an advanced aircraft that was developed by the United States and eight other countries. It has also been deployed to European countries and the US.
The Defense Ministry is considering working with the US to raise the plane as soon as possible in order to keep the technology secret.