As relations between Washington and Beijing crater, U.S. officials hope to rely more on America’s allies for support. Most important are Japan and South Korea.

However, ties between the two are tenuous, and Seoul’s Yoon government is suffering politically for making concessions to improve their relationship. It’s time for Washington to play alliance counselor.

Relations between the Koreas and Japan are badly burdened by history. The Kingdom of Korea was a tributary of the Chinese Empire but fell under Japanese domination in 1895. Fifteen years later Tokyo turned Korea into a colony and tried to remake Koreans as docile Japanese subjects.

Tokyo’s 1945 defeat freed the peninsula from Japanese control, but popular animus remains strong. Koreans remembered suffering under Japanese rule. Japan’s ethnic Korean minority faced discrimination and worse. Although Seoul and Tokyo normalized relations in 1965, demand for recompense from Koreans forced into labor and prostitution later disrupted relations between the two governments.

In 2015 Seoul and Tokyo reached an agreement to compensate the “comfort women” forced into prostitution by the Japanese military. But that pact soon collapsed. When litigation left courts threatening to seize Japanese property, Tokyo restricted trade with the ROK. Seoul then ended intelligence-sharing as part of the tripartite (with America) General Security of Military Information Agreement (GSOMIA).

The Trump administration convinced the South to reverse the latter decision, but Seoul-Tokyo relations remained in deep freeze. In October 2021 then-President Moon Jae-in met with Japanese Prime Minister Fumio Kishida. Moon sounded conciliatory but offered nothing new, while Kishida demanded “an appropriate response” to the issue. Observed researcher Justin Yeo: “Japanese society and the country’s political class have come to a near consensus opinion: No improvement of relations with the ROK is possible unless Seoul formally changes its position.”

South Korean President Yoon Seok-yeol, elected last year, recently proposed using a foundation funded by the ROK to compensate victims of the Japanese Empire as well as reinvigorating GSOMIA talks. Kishida responded by dropping trade restrictions on the South, while Japan’s Keidanren business organization announced creation of a joint scholarship fund to support student exchanges.

The Yoon plan enables both sides to step back from the brink, papering over a seemingly insoluble problem. Washington was pleased with the accord. Alas, Yoon’s statesmanship was not appreciated by his countrymen. The Nation’s Tim Shorrock warned that “Without a mechanism for reparations or a formal apology from Japan” the deal is likely to collapse like the previous one. Scott Snyder of the Council on Foreign Relations similarly worries that Yoon’s program “is at risk of failure in the absence of reciprocation.”

Indeed, some 60 percent of South Koreans oppose the agreement, angry that it does not include an admission of responsibility by Japan or force the latter to pay reparations.

Lee Jae-myung, head of the opposition Democratic Party, denounced “the most shameful and disastrous moment in our country’s diplomatic history” and complained that the ROK’s “national pride, victims’ human rights and historical justice were all exchanged for a bowl of omurice.”

With the National Assembly under DP control — and elections set for next year — Yoon will get little legislative help. Nor can his government easily clear away current court cases without the plaintiff’s consent. The ROK has sought Washington’s help to ease Yoon’s political pain.

Americans tend to see historical disputes as a wasteful distraction. However, it is difficult to forget or forgive past atrocities. Unfortunately, justice is impossible. The victors’ attempt to extract reparations from World War I’s losers fueled extremism and helped ignite an even worse conflict a generation later. After World War II no defeated power had the resources necessary to compensate more than a handful of victims. Today virtually everyone involved — decision-makers, perpetrators, and victims — has died. Younger Japanese are not responsible for the crimes of their elders.

Yet without some meaningful gesture from Tokyo bilateral relations seem condemned to endless frustration, vexation, and hostility. Nor is this the only historical issue to divide the two countries. Shortly after Yoon’s visit another textbook controversy broke out in Japan over language diminishing the imperial government’s responsibility for the conflict. The dispute reportedly “dominated South Korean media” and inflamed criticism of Yoon’s agreement with Kishida.

Washington should conduct low-key shuttle diplomacy between Seoul and Tokyo. What does the Yoon administration believe would help sell its policy? South Koreans don’t need to like the agreement. Reducing its electoral salience and moderating dislike of Japan would help build a broader political consensus, helping the agreement survive.

What is Tokyo prepared to do as a voluntary gesture rather than a judicial diktat? Encourage significant contributions from several Japanese companies — so far only two are before South Korean courts — to an ROK foundation? Strengthen tripartite security cooperation and highlight Seoul’s role? Create a new Japanese foundation to make donations in the South? Jointly commemorate the war’s end, or otherwise help mitigate wartime controversies? Stage a reciprocal and respectful visit by Kishida to Seoul? At the very least, stop inflaming South Korean passions by disclaiming responsibility?

Japan has much at stake in Yoon’s success. Should his party falter, any accommodation with Tokyo likely will be seen as political death. If the opposition holds onto its legislative majority and regains the presidency, ROK governments would be less willing to compromise.

The Biden administration should administer tough love to both parties. They can insult and sanction each other only because they enjoy American military protection. If something goes wrong, they expect to fall back on the U.S. The administration should indicate that Washington is under increasing fiscal pressure and has global responsibilities. Thus, it expects friendly powers, especially treaty allies, to do much more on their own behalf. Seoul’s and Tokyo’s cheap ride is ending. Cooperation is imperative.

Despite the issue’s emotional power, a solution is not impossible. Consider the long Greek-Macedonia deadlock over the latter’s name. Athens blocked Skopje’s accession to both the European Union and NATO, claiming that the new state formed after Yugoslavia’s dissolution had revanchist tendencies. Eventually the Greek government agreed to accept the name North Macedonia. Even that concession was controversial, with nearly 70 percent of Greeks opposed, but in 2019 a narrow parliamentary majority approved the accord.

Since then both nations have moved on—after spending nearly three decades convulsed by the issue.

World War II is long past but continues to warp the present. South Korea and Japan have yet to break its malign yet tenacious hold over their relationship. The ROK has made a move forward. Japan needs to reciprocate. Washington should help seal the deal.