File photo taken on Oct. 14, 2018 shows F-35A fighter aircraft from the Japan Air Self-Defense Force taking part in a military review at the Ground Self-Defence Force's Asaka training ground in Asaka, Saitama prefecture. (Xinhua/AFP)

WASHINGTON, April 25 (Xinhua) -- A privately owned deep-sea search vessel with U.S. Navy salvage team on board has departed for Okinawa, Japan to assist search operations for a downed Japanese F-35A fighter, U.S. Navy said in a statement Thursday.

The Vessel, DSCV Van Gogh, is a multipurpose diving support and construction platform equipped with U.S. Navy remotely operated vehicles and a towed-pinger locator system, said the statement.

A senior U.S. Navy official told CNN on Wednesday that search efforts are closing in on the aircraft's fuselage. "We have a pretty good idea where it is."

A Japanese Air Self Defense Force (JASDF) F-35A stealth fighter went missing while on training approximately 85 miles (137 km) east of Misawa Air Base on April 9.

Japan's Defense Ministry confirmed that the crash in waters off Japan's northeast was the first of an F-35A anywhere in the world.

The crash not only raised questions about the reliability of the U.S.-designed advanced fighter but also sparked concerns over the Japanese government's plans to buy 105 more of the 100-million-dollar fighters as it seeks to overhaul its aged fleet of mainstay jets as part of its controversial national defense guidelines.