Japan has grounded its entire F-15 fighter fleet following the crash of one of the jets into the East China Sea, officials said Wednesday.
Japan's Defense Ministry ordered the fleet to remain on the ground pending an investigation into the cause of the crash Tuesday, when an F-15 based on the island of Okinawa went down during a routine training mission.
The pilot of the jet remains missing and about a half dozen naval ships have been mobilized in a search for him, the ministry said in a statement. Debris from the jet's tail has been spotted in the ocean. It was not known if the pilot was able to eject before the crash.
Japan, with 202 F-15 fighters, is the biggest foreign user of the popular U.S.-designed planes but is currently looking for a newer aircraft to replace its aging fleet.
Though many upgrades and changes to the planes have been made over the years, F-15 fighters have been in service since the early 1970s and are increasingly expensive to maintain. The United States, which also relies heavily on the aircraft, is planning to phase out its F-15s in favor of the more advanced F-35 and F-22.
The Japanese versions of the plane, originally built by McDonnell Douglas, now Boeing, are produced domestically under a license by Mitsubishi Heavy Industries.