Photo/Illutration Prime Minister Shigeru Ishiba, right, and impeached South Korean President Yoon Suk-yeol ahead of their second meeting in Lima in November (Asahi Shimbun file photo)

The detention of South Korea’s impeached president, Yoon Suk-yeol, has clouded the outlook of Japan’s relations with its neighbor and the trilateral partnership with the United States.

Foreign Minister Takeshi Iwaya tried to downplay a potential fallout from Yoon’s detention on Jan. 15.

“The importance of Japan-South Korea cooperation will only increase and never decrease,” he told reporters in the Philippines.

Yoon faces insurrection charges over his short-lived imposition of martial law in December.

The detention came two days after Iwaya said he had witnessed a stable management of South Korea’s national politics during his visit to the country.

Prime Minister Shigeru Ishiba was expected to seek to build on improvements in Japan-South Korea relations made under his predecessor, Fumio Kishida, and Yoon.

Since taking office in October, Ishiba has met with Yoon twice. He gave up plans to visit South Korea this month after Yoon’s martial law declaration on Dec. 3 threw the country into turmoil.

Yoon is credited with improving bilateral relations, which have been strained by different perceptions of issues related to Japan’s 1910-1945 colonization of the Korean Peninsula.

He struck a political settlement with Kishida concerning a longtime row over laborers from the Korean Peninsula who toiled in Japanese factories and mines during World War II.

For years, Seoul opposed Tokyo’s bid to inscribe one such site, gold mines on Sado Island, on UNESCO’s World Cultural Heritage list, saying they are a site of forced labor.

The two countries reached a compromise, paving the way for the mines in Niigata Prefecture being registered as a World Cultural Heritage site in July.

Historical issues can easily flare up, however.

In November, South Korea boycotted a memorial for workers who died in the mines, citing disagreements with Japan, and organized a separate ceremony for Korean laborers.

The Democratic Party of Korea, South Korea’s main opposition party that has confronted Yoon, has taken a tough stance on history issues with Japan.

U.S. President Joe Biden, who forged closer three-way cooperation with Tokyo and Seoul, will be replaced on Jan. 20 by Donald Trump, who advocates an America First agenda.

When ties between Japan and South Korea soured, Washington traditionally served as a mediator to stabilize bilateral and trilateral relations.

However, Trump, who is dismissive of multilateral cooperation frameworks, was indifferent to collaboration among Japan, the United States and South Korea the last time he was in the White House.

In 2019, South Korea came close to scrapping the General Security of Military Information Agreement, which facilitates the sharing of military intelligence with Japan, when the bilateral relationship hit one of its lowest points after World War II.

(This article was written by Nen Satomi and Toshiya Obu.)