Lost secrets?

What We Know About Mysterious Crash of F-35A off Japan

Despite finding some of the parts of the crashed jet, Japanese investigators are still having trouble determining the cause of the accident, as the jet's black box has still not been located.

The top stealth fighter jet disappeared from radars on 9 April during drills 135 km northeast of Misawa city. Japan, joined by some US forces, launched a massive search operation for the wreckage of the jet and its pilot on the same day, but so far little progress has been reported. Search teams have found parts of the plane floating on the surface of the sea, confirming that it crashed, but the precise cause of the incident and the pilot's fate remain a mystery.

...During the first couple of days, the country deployed numerous ships and aircraft to participate in the rescue operation, but the amount was subsequently reduced. The US has also sent forces, such as the USS Stethem (DDG 63) destroyer, Navy P-8 Poseidons, and U-2 Dragon Lady reconnaissance jets, and even B-52 bombers from an air base in Guam. Japanese Defence Minister Takeshi Iwaya also revealed on 12 April that the country had initiated an underwater search as well.

According to some media outlets, such as Nikkei, the intense efforts to locate and recover the F-35A's wreckage are tied to fears that the advanced technology used in the jet could fall into the hands of China or Russia.

The media outlet indicated that the US has given "a never-before-seen level of priority on this crash", devoting spy jets, bombers, and Navy vessels to find a single crashed F-35.