A dispute over the history of a 400-year-old gold mine has touched off fresh animosity between Japan and South Korea, just as the Biden administration needs their cooperation to confront new North Korean weapons that threaten the US allies.

Japan’s cabinet decided Tuesday the government would seek a Unesco World Heritage List designation for the mine on the island of Sado, which started operations about four centuries ago and closed in 1989. South Korea contends Tokyo is looking to whitewash the facility’s use of forced labor from the Korean Peninsula and has expressed “strong regret” over the the campaign.

“The Sado gold mine is a rare example of industrial heritage that operated continuously on a large scale,” Chief Cabinet Secretary Hirokazu Matsuno told reporters in Tokyo after the decision. “We intend to discuss it calmly and carefully with related countries, including South Korea.”

The battle over the mine could set the tone for Japan’s ties with its neighbor, after Prime Minister Fumio Kishida took office in October and with South Korea set to pick a new president in just over a month.

The Japanese government has said little about the human rights conditions at the mine. More than 2,000 Koreans worked there when Japan colonized the Korean Peninsula from 1910-1945, according to a report from the Yonhap News Agency in South Korea. The silence on the issue from Tokyo has raised concern in Seoul.

South Korea’s Foreign Ministry in late January said in a statement it “sternly urges Japan to stop its attempt” to seek the Unesco distinction. It has previously said it would campaign “to prevent sites where people were forced to work against their will from being inscribed as a World Heritage site without sufficient explanation of such historical facts.”

The neighbors had a similar dispute over the Hashima industrial site off the coast of Nagasaki that is already a Unesco World Heritage Site. About two years ago, South Korea expressed anger after Japan opened an information center in Tokyo that included materials suggesting conscripted Korean workers at Hashima were paid and well-treated -- saying it broke a deal the two reached to acknowledge the harsh labor conditions.

The top diplomats from the US, Japan and South Korea are due to meet this month, according to reports from the Yonhap and Kyodo news agencies. The Sado mine issue could cloud their discussions on a new array of weaponry North Korean leader Kim Jong Un has unveiled in recent months designed to deliver nuclear warheads to South Korea and Japan.

South Korea and Japan, major trading partners, have been at loggerheads for years over what constitutes proper contrition and compensation for Koreans conscripted to work in factories and mines that supplied Japan’s imperial war machine during the colonial period, and those euphemistically called “comfort women,” who were forced to work in military brothels.

The forced labor issue is a small part of the history of the Sado gold and silver mine, which once helped fund Japan’s shogunate in the 1600s. It was the country’s most productive mine for centuries and produced at least 78 t of gold and 2 330 t of silver until its operations came to end about three decades ago upon depletion.