A U.S. F-16 fighter jet accidentally released a dummy bomb over 200 kilograms during training outside a firing and bombing range near Misawa Air Base in northeastern Japan, the Defense Ministry said Thursday.
There was no report of injury or damage in the incident which occurred at around 6:35 p.m. Wednesday in Aomori Prefecture, according to U.S. Forces Japan.
The ministry lodged a protest with the U.S. military over the incident after the Japanese government was notified of it Thursday morning.
While the cause of the incident is still under investigation, U.S. aircraft at the Misawa base have suspended inert drops until further notice, the U.S. forces said.
"The dropped object is quite heavy and it must not happen. We will ask (the U.S. side) to take effective measures to prevent similar incidents from happening again," Chief Cabinet Secretary Yoshihide Suga said at a press conference.
Suga said Japanese government officials are also conducting an on-site investigation of the incident.
According to the Aomori prefectural government, the dropped object was found about 5 kilometers west of the bombing range. There are no houses around the area.
The 7.66-million-square-meter training ground is located around 20 kilometers north of the Misawa base and used by both U.S. military and the Japanese Self-Defense Forces.
It is the only site on the country's main island of Honshu where air-to-ground firing and bombing drills can be conducted, according to the ministry.