An Air Self-Defense Force F-15 fighter from the Naha Air Base in Okinawa Prefecture apparently went down Tuesday morning in the East China Sea during a training flight and the pilot is listed as missing, Defense Ministry officials in Tokyo said.

The ASDF and Maritime Self-Defense Force have discovered what appears to be pieces of an aircraft floating near the area where radar contact with the fighter was lost.

The F-15J disappeared from radar around 10:33 a.m. over the sea approximately 185 km northwest of the Naha base while it was engaging in a training mission with three other F-15s, Defense Ministry officials said.

"We are currently investigating the details of the accident, and doing everything we can to search for the missing pilot. We will provide continuous updates on any discoveries we find," Shigeru Iwasaki, ASDF chief of staff, said in a prepared comment.

The missing pilot as identified as Maj. Yuji Kawakubo, 37, a veteran with more than 3,000 hours of flight time, including 1,700 in F-15s.

Kawakubo was engaging in combat drills with the other fighters when his plane went down.

ASDF officials said they have found no evidence to suggest he managed to eject.

The other fighters spotted the floating debris at 10:46 a.m. The missing plane's tail fin was discovered at 11:12 a.m. by an MSDF P-3 patrol aircraft and an ASDF rescue aircraft.

At 11:39 a.m. the rescue aircraft discovered a speed brake and portions of a tail.

While the reason behind the accident remains unknown, ASDF officials said it was "highly likely" the F-15 crashed into the sea.