Japanese navy divers detonate two dozen shells believed to be from World War II at Naha Port, Okinawa, March 12, 2025. (Brian McElhiney/Stars and Stripes)
NAHA, Okinawa — Japanese troops detonated 24 suspected U.S. shells off the coast of Okinawa’s capital Wednesday, the third disposal of World War II ordnance in a month on the former island battleground.
Eleven explosive ordnance disposal divers from the Japan Maritime Self-Defense Force’s Sub Area Activity Okinawa unit set off the explosives underwater at 1 p.m., about 2,300 feet offshore from Shinko, one of four wharves at Naha’s civilian port.
The blast, which destroyed more than 1,630 pounds of ordnance, shook the two-story Naha Ecoisland waste disposal building near Pier 10, where Self-Defense Force personnel and media gathered to observe.
Vessels were barred from entering a 980-foot radius around the site, and swimmers and divers were restricted within a nearly two-mile radius starting at 9:30 a.m., according to an announcement posted Feb. 27 on Naha city’s website. Restrictions were lifted at 2 p.m.
The shells were discovered during construction work in the port’s harbor between January and November 2024 and had been stored underwater near the detonation site, the city’s announcement said.
The recovered ordnance included three 275-pound bombs, seven 5-inch shells, one 5-inch shell casing, one 4-inch shell, four 3-inch shells, seven 81-mm mortars, and one 110-pound bomb fragment.
Divers secured the shells with sandbags 50 feet below the surface before using C-4 explosives to destroy them, a Maritime Self-Defense Force spokesman told Stars and Stripes before the detonation. He did not specify how much C-4 was used.
The site has been used before for multiple detonations. Naha officials destroyed a 14-inch shell and a 5-inch shell in January 2024 and a 550-pound bomb in December 2023.
Similar operations have taken place elsewhere on Okinawa. On Feb. 13, ordnance disposal divers destroyed 461 U.S.-made, WWII-era shells a mile offshore of Nakagusuku Bay Port in Uruma. The following day, Japan’s Ground Self-Defense Force detonated 138 shells on land on Ie Shima, an island off the Motobu Peninsula, according to Japanese public broadcaster NHK.
On Feb. 25, members of the Ground Self-Defense Force’s 101st Explosive Ordnance Disposal Unit defused a U.S.-made 5-inch shell found in January by construction workers in Urasoe.
The Japanese government has increased efforts to locate unexploded ordnance at airports nationwide.
Authorities began surveys in October at Miyazaki Airport on Kyushu — the southernmost of Japan’s four main islands — after a WWII-era bomb exploded on a taxiway. Magnetic surveys followed in December at Naha Airport and airports in Sendai, Matsuyama and Fukuoka.
