Nearly 600 unexploded shells from World War II's Battle of Okinawa have been retrieved from Okahajima, a small Okinawa island popular with kayakers. (Keishi Koja/Stars and Stripes)

ITOMAN, Okinawa — Hundreds of unexploded, U.S.-made shells believed to date to the Battle of Okinawa have been recovered from a small island by the Japan Ground Self-Defense Force.

Eleven members of the 101st Explosive Ordnance Disposal unit, assisted by 10 members of the Maritime Self-Defense Force, collected 420 shells Wednesday and another 160 Thursday from Okahajima, a spokesman for the Ground Self-Defense Force’s 15th Brigade told Stars and Stripes by phone Friday.

Okahajima, a half-mile from Itoman city, is a small island popular with kayakers.

The shells were mostly 3.5- and 3-inch rounds and white phosphorus bombs. The work was complete by noon Friday, the spokesman said.

Japanese police and the Self-Defense Force discovered the shells in February after tourists reported smoke on the island, the brigade spokesman said. Some government spokespeople in Japan are required to speak to the media only on condition of anonymity.

The spokesman said the removal went forward “without any trouble” and the collected shells were taken to a Ground Self-Defense Force base. They will be detonated or disposed of at a later date.

“It is very unusual to collect this amount of unexploded ordnance,” the spokesman said. "Most of the shells were from U.S.-made bombs. There were also shells from Japan-made bombs."

Approximately 10,000 tons of ordnance fell on Okinawa during the war and nearly 2,000 tons remain undiscovered, according to the prefecture’s General Bureau website. More than 13 tons were disposed of between April 1, 2021, and March 31, 2022.

“We do not know why so many shells were placed on this small island," a spokesman for the Itoman city Disaster Prevention Department said by phone Friday.