The jet crashed on April 9 during an Air Self-Defense Force night exercise after having taken off from Misawa Air Base in Aomori, sources report. The pilot of the stealth jet is also missing.

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Now, Japan and the US are worried about the consequences of the aircraft being discovered by other countries. They specifically believe that such a development could be a major military intelligence breach.

In addition, science minister Masahiko Shibayama told that the research vessel Kaimei, which the Japan Agency for Marine-Earth Science and Technology owns, will also join in the operation, after a request from the Defense Ministry.

The ship has a remotely operated vehicle, able to observe up to a depth of about 3,000 meters.