An explosion occurred at the northern section of a munitions storage area on Kadena Air Base, Okinawa, June 9, 2025. (Keishi Koja/Stars and Stripes)
An explosion last month at a munitions storage facility on Kadena Air Base, Okinawa, occurred when Japanese soldiers accidentally detonated a fuse on a World War II-era anti-tank shell, Japan’s military said Thursday.
The U.S.-made 75 mm shell exploded June 9 as four members of the Japan Ground Self-Defense Force inspected it for an unexploded fuse, according to an investigation report released by the service. The soldiers were preparing the shell for handover to a contracted disposal company.
The fuse detonated when one of the soldiers struck the shell with a tool while attempting to remove rust, a Ground Staff spokesman said by phone Thursday.
All four soldiers were treated for blast injuries at a local hospital, the Yomitan Fire Department told Stars and Stripes on June 9. One man in his 40s suffered minor to moderate injuries to his left hand, while the other three sustained minor injuries, including hearing issues. One soldier also had a scratch on his right arm and left cheek.
All have since recovered and returned to duty, the Ground Staff spokesman said. It’s customary in Japan that some government officials speak to the media only on condition of anonymity.
The shell had been stored with other unexploded ordnance, believed to date to WWII, in a temporary storage facility at the Kadena Ammunition Depot, which is managed by the Okinawa prefectural government.
The report cited the outsourcing of disposal work as an indirect cause of the accident.
Going forward, the Ground Self-Defense Force will prohibit “actions that may impact the fuse or the use of tools that may cause such impacts,” according to the report. It also plans to detonate unexploded ordnance if the fuse’s integrity cannot be confirmed, rather than outsourcing its disposal.
The report also said the force would “strive to secure more opportunities for disposals through detonations.”
Personnel and commanders will be retrained on safety protocols, and new protective equipment will be introduced for ordnance disposal work, the report said. The equipment is still being considered, the Ground Staff spokesman said.
Japan’s military temporarily paused rust removal on unexploded ordnance at storage facilities across the country during the investigation. Operations are expected to resume once new safety measures are in place, the spokesman said.
No U.S. personnel were involved in the incident, the 18th Wing at Kadena said in a statement the day of the explosion.
Unexploded ordnance from the 1945 Battle of Okinawa continues to be discovered across the island, including at former battlefield and construction sites. Between April 2023 and March 2024, nearly 22 tons of WWII-era ordnance were disposed of on the island, according to the Okinawa General Bureau’s website.
