Debris left inside the barrel of a Type 10 tank likely caused the explosion that killed three Ground Self-Defense Force members and injured a fourth during live-fire training in Oita Prefecture in April, according to defense ministry officials. The Ground Self-Defense Force is preparing to publish its accident investigation report before the end of the year.
The accident occurred at about 8:40 a.m. on April 21, during a live-ammunition drill by the GSDF's Western Army Tank Unit at the Hijudai training area. A 120-millimeter anti-tank high-explosive shell burst inside the turret, the rotating gun mount on top of the tank. Three members inside the turret were killed, and a fourth, positioned away from it, was seriously injured.
How the Type 10 loads and fires
The Type 10 feeds shells stowed in the turret automatically into the barrel on a belt. The barrel is sealed after loading, and the crew fires by pressing a button manually. According to the officials, the 120-millimeter anti-tank shell burns up when fired, but residue occasionally remains inside the barrel.
Six Type 10 tanks took part in the drill, and the tank involved had fired several rounds. When a new shell was loaded for the next shot, the previous shell appeared to have burned incompletely and left debris in the barrel, causing a reaction that set off the round. The breech block, which seals in the blast, was reportedly not closed, and the crew inside the turret was caught in the explosion.
The Type 10 is a domestically produced tank adopted for service in 2010. As of the end of fiscal 2025, the GSDF held about 120 of them, including at the Kusu garrison in Oita Prefecture, the base for the Western Army Tank Unit, and in Hokkaido.