Seoul: Bound by proximity, yet estranged by the past, relations between South Korea and Japan have undergone times of turbulence since normalizing diplomatic ties six decades ago, following Japan's colonial rule over the Korean Peninsula.

According to Yonhap News Agency, the two neighboring countries in the present day share much in common: They are both rules-based democracies, key Asian security allies of the United States, and major economic powers. Yet unresolved disputes over wartime history have remained a constant source of friction, keeping them at odds.

As South Korea and Japan mark the 60th anniversary of the normalization of diplomatic ties on June 22, they find themselves at another pivotal moment in their relationship, with the launch of a new South Korean government and growing economic and security challenges in a shifting geopolitical landscape.

The 1965 treaty that normalized Seoul-Tokyo relations arguably patched up a long-standing feud rooted in Japan's colonial rule over Korea from 1910-45 and the atrocities committed by Tokyo during that period. After 14 years of unsuccessful negotiations by previous leaders, the signing of the normalization pact was a strategic move by then South Korean President Park Chung-hee to rebuild his country from the ruins of the 1950-53 Korean War, with help from the neighboring nation.

Under the settlement agreement, signed along with the normalization treaty, South Korea received US$800 million in grants and soft loans from Japan as compensation for its colonial occupation. The normalization pact helped facilitate South Korea's rapid economic growth. But many South Koreans believe it failed to adequately address the wartime suffering of Koreans. Japan maintains its stance that all reparation issues were resolved under the settlement.

This discrepancy has continued to create disputes over pending issues of Japan's sexual enslavement of Korean women, its forced mobilization of Koreans to mines and factories during World War II, its territorial claims over South Korea's Dokdo islets, and related distortion of history in school textbooks.

Over the years, Japanese leaders expressed "deep remorse and heartfelt apology" in key statements issued in 1993, 1995, and 2005 over the country's colonial rule and wartime aggression. But those efforts were largely overshadowed by the growing influence of domestic politics in both countries, with Japan's political mainstream increasingly leaning to the right, and South Korean politics often divided between pro- and anti-Japan blocs.

Bilateral ties hit a low in the 2010s, often referred to as a "lost decade," with no leader-level exchanges or summits taking place during the period. The feud intensified during former President Moon Jae-in's administration, following South Korea's Supreme Court rulings in 2018 that held Japan still responsible for compensating victims of forced labor.

Tokyo retaliated against Seoul with export controls on key industrial materials vital to South Korea's manufacturing sector. In response, Seoul announced a decision to terminate a bilateral military information-sharing pact with Japan. The deteriorating relations took a dramatic turn under the conservative Yoon Suk Yeol administration. Yoon announced in March 2023 the government will compensate forced labor victims without Japan's involvement.

Yoon's decision lifted a burden Tokyo had never agreed to take on, leading to a thaw in relations. Yoon met 12 times with then Japanese Prime Minister Fumio Kishida, marking the resumption of the "shuttle diplomacy" of regular visits by leaders. The turning point was strongly welcomed by Washington, paving the way for the launch of a trilateral cooperation framework that was reinforced at the Camp David summit among Yoon, Kishida, and then U.S. President Joe Biden in August 2023.

Newly sworn-in South Korean President Lee Jae-myung, who's known for his hard-line stance on Japan, has signaled his intent to maintain the current course in relations with Tokyo, including upholding his predecessor Yoon's solution to the wartime forced labor issue. Lee has pledged to pursue a "two-track" approach, separating historical disputes from forward-looking cooperation, to keep positive momentum alive in bilateral relations.

But doubts still linger over whether, and for how long, Lee will be able to keep his commitments. As the opposition party leader, Lee had denounced the Camp David summit as a "'losing move' that turns back the wheel of history to a time before Korea's liberation from Japan." Lee once called South Korea's joint military drills with the U.S. and Japan "an extreme pro-Japan action."

"I believe Japan is keen on maintaining good relations with South Korea," Shin Kak-soo, former South Korean ambassador to Japan, said by phone. "However, Japan does not easily let go of distrust." South Korea and Japan face a series of unresolved issues in the months ahead. A bilateral agreement on the joint development of an underwater continental shelf is set to expire this month, with Japan widely expected to withdraw from the deal.

Tensions also remain over wartime history issues. Last year, South Korea boycotted a memorial event in Japan honoring Korean laborers forced to work at the Sado mine complex during wartime. Seoul cited Japan's lack of sincere efforts to acknowledge the victims, despite having agreed to the site's inscription on the UNESCO World Heritage list. This year's event is expected to take place after the summer.

Experts said the Lee government needs to present a clear vision and principles for relations with Japan, whether it be about future cooperation or past history issues. "The president calls for 'pragmatic diplomacy centered on national interests,' but he needs to define what those interests are in relations with Japan, especially with regard to sensitive issues," said Choi Eun-mi, a research fellow at the Asan Institute of Policy Studies.

It also remains to be seen what message Lee will give to Japanese Prime Minister Shigeru Ishiba during their expected meeting on the sidelines of the Group of Seven summit in Canada this weekend, Choi added. In his first phone call with Ishiba, Lee underscored the importance of Seoul-Tokyo relations and trilateral cooperation with the U.S. to work together on "various geopolitical crises," apparently referring to North Korea's nuclear and missile threats and its expanding military ties with Russia.

"Seoul-Tokyo relations have often been treated as a domestic issue in Korea because of their deep historical ties. But they should be approached as a matter of foreign policy. The strategic cooperation with Japan is so important in the current security situation," Shin said. "As President Lee has emphasized continuity, it's important not to make bold assurances. The relationship should be handled cautiously and demonstrated through concrete actions."