This 60-mm mortar shell, believed to be American in origin, was discovered at Okinawa’s Naha Airport, Oct. 3, 2024. (Japan’s Ministry of Land, Infrastructure, Transport and Tourism)

CAMP FOSTER, Okinawa — Japanese troops removed a second piece of unexploded, World War II-era ordnance in less than a week from Okinawa’s capital city, this time at the airport.

The 60-mm mortar shell, believed to be American in origin, was discovered at Naha Airport around 9:30 a.m. Thursday, an airport spokesman said by phone Friday.

A construction worker found the shell in a restricted area about 1,640 feet south of the control tower, the spokesman said. Japan Ground Self-Defense Force soldiers collected the shell at 12:08 p.m.; there was no risk of it exploding, he said.

This is the seventh unexploded ordnance found at the airport this year, the spokesman said. On Okinawa, a magnetic survey is required ahead of any public construction work, he added.

“The other ordnances were found at the green area next to the runway during these surveys, which are carried on at night while the runway is closed, usually between 2 a.m. and 3 a.m.,” he said. “All of them were collected by Self Defense-Force officials because none of them were at danger of exploding.”

Some Japanese government officials are required to speak to the media only on condition of anonymity.

On Sept. 29, Japanese troops successfully disarmed and removed a suspected WWII-era bomb from a sewage system construction site in Naha after evacuating 1,400 people,

The mortar shell was discovered at Naha Airport a day after a 500-pound, World War II-era U.S. bomb lying beneath Miyazaki Airport in southern Japan exploded, cratering a taxiway and causing the cancellation of more than 80 flights, The Associated Press reported Wednesday.

No one was injured in the explosion, according to the report.

Tetsuo Saito — the minister of Land, Infrastructure, Transport and Tourism — said at a news conference Friday that the ministry will make an emergency magnetic survey at Miyazaki Airport. The Sendai, Fukuoka and Naha airports will be also considered for surveys, according to a transcript of Saito’s remarks uploaded to the ministry’s website.

The Miyazaki shell was beneath the taxiway shoulder, where the asphalt is thinner than the taxiway and runway. The magnetic surveys will be done mainly in that area of the airports, according to Japanese broadcaster NHK, which cited ministry officials.

The Naha Airport spokesman said the airport conducts magnetic surveys only in the areas within the scope of construction work.

“I know about the report, but we haven’t heard anything from the ministry yet,” he said.

Approximately 2,000 tons of ordnance remains undiscovered out of 10,000 tons dropped on the island during the Battle of Okinawa, according to the prefecture’s General Bureau website.

Crews disposed of nearly 22 tons of unexploded ordnance between April 1, 2023, and March 31.