A U.S.-made wartime bomb that unexpectedly detonated at Miyazaki Airport in October 2024 likely contained a timed detonator designed to delay the fuse's activation, according to a Defense Ministry investigation.

Experts have identified the bomb as one of the explosives dropped by U.S. forces during World War II. The bombs employed chemical reactions to activate their fuses and were intended to temporarily disable bases used by the Imperial Japanese military for suicide attack missions.

Ahead of next summer's 80th anniversary of the end of the war, the blast serves as a sobering reminder of the lingering legacy of wartime U.S. air raids on Japan.