As Security Threats Mount, Japan and South Korea Begin (Carefully) Mending Fences

SEOUL—When new South Korean President Yoon Suk-yeol first took office in May, all eyes were on the RSVP list for the inauguration ceremony—and, more specifically, just who exactly was going to show up from Japan.

In the world of diplomacy, subtlety reigns king, and who doesn’t attend a major ceremony matters as much as who does. The big questions over which Japanese officials would attend the South Korean presidential inauguration highlighted the fraught state of relations between two of Washington’s closest allies in the Asia-Pacific.

In the end, Japan tried to thread the needle by sending a delegate who was high-level enough but not quite the highest: Tokyo spurned Seoul’s request to send Japanese Prime Minister Fumio Kishida to the inauguration, opting instead to send Japanese Foreign Minister Yoshimasa Hayashi. It was as clear a signal as any that Japan is willing to talk to South Korea about finally patching up their strained relationship, but any long-term fix to their simmering political disputes won’t come easy.

Relations between modern-day Japan and South Korea sunk to their lowest levels in recent years, clouded by unresolved conflicts from Japanese atrocities committed during its brutal 1910-1945 occupation of Korea. During former South Korean President Moon Jae-in’s tenure, beginning in 2017, Japan and South Korea halted joint military drills with the United States and Seoul effectively tabled an intelligence-sharing pact with Tokyo, as the political fallout from their historical grievances clouded the relationship.

But now, with new leaders in place in both countries and looming threats from North Korea and China knocking on their doors, South Korea and Japan may finally be ready to turn a new leaf—or barring that, at least nudge it in the right direction.

For Washington, the question of how well South Korea and Japan get along is of vital importance to national security. The United States relies heavily on both allies to tackle overlapping threats from China, which it views as a long-term global superpower competitor; Russia, amid the fallout from Moscow’s military invasion of Ukraine; and North Korea, which has stubbornly expanded its ballistic missile and nuclear weapons programs despite damaging international sanctions.

“[T]he Indo-Pacific is on edge, worried about China’s behavior especially in the wake of Russian aggression,” wrote Sheila Smith, a scholar on Asia-Pacific studies at the Council on Foreign Relations, in an email. “[T]he U.S. and its allies are building a coalition strategy to manage the new pressures of the Chinese (and now Russian) challenge to the status quo. So encouraging Seoul and Tokyo to improve ties has real strategic import.”

But the United States has to be careful in how it tries to foster Seoul and Tokyo into mending fences. Push too softly, and those efforts may lose momentum. Push too hard, and the United States could risk stoking backlash in both countries and invite criticism that Washington is meddling in sensitive historical and domestic political questions.

Still, policymakers in Washington are hopeful that the stars are aligning for a new era in South Korea-Japan relations under the Yoon and Kishida governments, where if both countries can’t find a way to permanently fix their dispute, they can at least set them aside long enough to cooperate on security.

In Seoul, Yoon and his new conservative government have declared that improving relations with Japan is a top foreign-policy priority, and there’s ample evidence to suggest it’s more than just talk, according to interviews with multiple South Korean officials and experts.

(Foreign Policy reported from Seoul as part of a journalism fellowship organized by the Atlantic Council and Korea Foundation.)

Yoon has stacked senior positions in his government with experts who have been vocal advocates for improving bilateral ties. This includes South Korean Foreign Minister Park Jin, who played an outsized role during his time in the National Assembly working to address hang-ups in the Japan-South Korea relationship, South Korean National Security Advisor Kim Sung-han, a well-known foreign-policy expert who has pushed for closer trilateral cooperation with Washington and Tokyo, and South Korean Deputy National Security Advisor Kim Tae-hyo, an academic and former official in former South Korean President Lee Myung-bak’s administration from 2008 to 2013, who is also known for advocating closer South Korea-Japan ties.

“Given the personnel appointments, the Yoon Administration is taking its foreign-policy aims seriously, and especially notable is the expertise and familiarity the Yoon team has with Japan,” Smith wrote.

Already, the Yoon government has signaled it wants to improve ties with Japan by reviving the joint intelligence-sharing pact, known as GSOMIA, and possibly restarting trilateral military exercises as a deterrent against provocations from North Korea.

Although the Kishida government in Tokyo has taken a more hawkish approach to China than its counterpart in Seoul, there is growing concern in South Korea about what China’s sharp bent toward authoritarianism and more muscular foreign policy will mean for security on the Korean Peninsula in the future.

In both cases, South Korean officials widely believe their best bet lies with deepening ties with the United States and Japan to hedge against any further tensions with Beijing or Pyongyang.

Yoon’s party “knows the strategic importance of the relationship [with Japan] very well, but due to politics and historical sensitivities, it will have to move very cautiously,” said one member of South Korea’s National Assembly, who spoke on condition of anonymity to discuss sensitive issues.

U.S. President Joe Biden, meanwhile, is pushing for both countries to deepen their political and security cooperation through a series of carefully choreographed trilateral meetings.

On the margins of a NATO summit in Madrid on Wednesday, Biden met with Kishida and Yoon, marking the first meeting with leaders from all three countries since 2017.

The trilateral summit, according to officials familiar with the matter, marked a diplomatic success but came as something of a consolation prize: It came after South Korea and Japan failed to find a way to arrange their own separate bilateral summit on the sidelines of the NATO meeting, leaving the United States in a position to convene both sides in a three-way meeting.

Still, the early signs out of Madrid show that things seem to be working. Yoon touted cooperation with Tokyo and Washington as a bulwark against the threat of Pyongyang. “[North Korea’s] nuclear and missile threats continue to evolve, and the global landscape is facing increased uncertainties, thereby rendering our trilateral partnership all the more significant,” he said.

And Kishida added some diplomatic overtures of his own during the marathon of meetings in Madrid. “I know that President Yoon is working hard for Korea-Japan relations,” Kishida said. “Let’s make efforts to develop the Korea-Japan relationship into a healthier one.”

From the Japanese side, working on mending fences with South Korea could prove more difficult before its upcoming elections for its House of Councillors in July, lest it open Kishida’s party up to political attacks for unpopular foreign-policy moves. But after that, both South Korean and U.S. officials say there will be breathing room in both countries to work on patching up the relationship.

Much of the tension stems from disputes on whether Japan has done enough to make amends for its brutal treatment of forced laborers from Korea and its practice of forcing Korean women into sexual slavery up until World War II ended and the Japanese empire dissolved.

Japan insists that it resolved all compensation issues related to the survivors and victims in Korea under a 1965 treaty and a 2015 deal aimed at settling the issue of so-called comfort women. But in 2018, the South Korean Supreme Court ordered Japanese companies to pay reparations to surviving forced laborers from the wartime era, sparking a series of tit-for-tat economic and diplomatic reprisals that strained bilateral ties.

“There will need to be demonstrable steps that restore confidence in diplomatic efforts between the two,” Smith wrote. “Do not expect everything to be resolved at once.”