Workers on Monday prepared a garden outside the international media center ahead of the Trump-Kim summit in Hanoi. (SeongJoon Cho/Bloomberg)

Yoichi Funabashi is chairman of Asia Pacific Initiative, a Tokyo-based think tank.

As President Trump and Kim Jong Un meet for the first time since their historic meeting in Singapore last year, it is vital that the United States has the joint backing of Japan and South Korea, which, through trilateral cooperation, can play a crucial role in strengthening Washington’s hand in pushing for North Korea’s denuclearization.

Unfortunately, relations between Tokyo and Seoul are at a historic low. As former South Korean Foreign Minister Gong Ro-myung has lamented, relations between the two countries are “the worst they have been since the normalization of relations” in 1965.

If people are unaware of the deterioration in relations, then the upcoming centenary of the March First Movement will no doubt make clear the severity of the “compound fracture” in relations. For Koreans, March 1, 1919, marks the formal independence of Korea, which at the time triggered as many as 2 million Koreans to protest against Japanese colonial rule.

Recently, relations have soured so far as to even have consequences in the security sphere. In October, Japan decided to skip naval drills in a controversy over its “Rising Sun” flag, while more recently, tensions arose when Japan and South Korea accused each other of “extremely dangerous” and “hazardous” practices over an incident involving a Japanese plane being tracked by South Korea’s fire-control radar. Of all the issues, however, it is the latest dispute over requisitioned workers from the Korean Peninsula that is perhaps most concerning.

In 1965, in addition to the Treaty on Basic Relations, Japan and South Korea signed an agreement stating that the ”problem concerning property, rights and interests of the two Contracting Parties and their nationals problems were . . . settled completely and finally.”

However, last October, the South Korean Supreme Court upheld an earlier decision, in which it found that Nippon Steel & Sumitomo Metal Corp. should compensate requisitioned workers from the Korean Peninsula during the period of Japanese colonial rule.

The South Korean Supreme Court takes the position that Japan did not acknowledge the “unlawfulness” of colonial rule and thus “denied legal compensation” from the requisitioned workers. The administration of Japanese Prime Minister Shinzo Abe has condemned this ruling, calling it “extremely regrettable” and “inconceivable in light of international law.” South Korean President Moon Jae-in has argued that claims of the individual workers remain.

The Moon administration is stuck in a dilemma. Siding with the ruling has resulted in a diplomatic fallout with Japan, but undermining his country’s Supreme Court would have risked a constitutional crisis.

This comes in the context of South Korea’s indictment of its former chief justice, Yang Sung-tae, for abusing his power and developing overly friendly relations with disgraced former president Park Geun-hye. Given the emotionally charged and politically sensitive atmosphere surrounding the Supreme Court, Moon dare not risk going against the most recent ruling.

By placing the administration in this position, the Supreme Court has opened a Pandora’s box at both the bilateral and global level. It has paved the way for as many as 23 million Koreans who lived under colonial rule to also seek compensation. At a broader level, the ruling also opens the door for past victims of other wartime atrocities to make individual claims — even where such issues were deemed to have been resolved through comprehensive peace treaties.

Japanese Foreign Minister Taro Kono said during an interview with Bloomberg News that the decision puts into question the commitment of the Korean government to international agreements. The ruling has not only weakened the ability of the Korean government to sign agreements, but also reduced incentives for other governments to negotiate with Seoul through diplomacy.

Gong, the South Korean foreign minister, has suggested that the South Korean government take the initiative to establish a fund to address the issue of requisitioned workers with initial contributions from South Korean companies, with the view that contributions from Japanese companies would then follow. The thought behind this is to create much needed space for reconciliation through diplomacy following the example of German funds such as the Foundation Remembrance, Responsibility and Future.

However, both Tokyo and Seoul appear to have dismissed this possibility. A spokesperson for the presidential Blue House, Kim Eui-kyeom, has said that “the idea itself is absurd” and that “the decision of the Supreme Court must be respected.” Meanwhile, the Japanese government believes this approach would be difficult as Germany and Japan are in fundamentally different situations. The Japanese government believes the division of Germany into East and West after World War II precluded the possibility of an inter-state claims agreement.

As a result of the challenges to resolving the issue bilaterally, the Japanese government is considering taking the issue to international adjudication and the International Court of Justice (ICJ). However, the prime minister of South Korea, Lee Nak-yeon, has already dismissed this. Given that the ICJ depends on participation of both countries, this legal route seems unlikely.

The two countries are at a crisis. Though international law is crucial to preserving the liberal international order, framing the issue as a legal matter has offered little progress. All parties must, therefore, recognize the diplomatic crisis and be aware of the broader geopolitical consequences of the fallout.

It is a shame that bilateral negotiations have stalled at a time when the citizens of South Korea and Japan are increasingly engaging in cultural exchange. This is reflected in the explosion in popularity of K-pop groups such as TWICE in Japan, as well as the continued increase in the number of South Korean tourists visiting Japan.

However, cultural exchange alone cannot resolve the issues between the two countries.

Instead, the Abe and Moon administrations must swiftly show robust political leadership to create a less hostile atmosphere where civil society can drive an improvement in relations. In doing so, Tokyo and Seoul can reduce the gap between deteriorating government-level relations and in the willingness and desire to improve relations that exists at the civilian-level.

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