Japan and South Korea are moving into one of the warmest periods of cooperation they have seen in years, and it is happening as relations with China continue to grow colder. This week’s summit in Nara between Japanese Prime Minister Sanae Takaichi and South Korean President Lee Jae Myung showed how strongly both countries now feel about standing together in a region shaped by growing Chinese power and uncertainty from the United States.
The two leaders met in Takaichi’s home prefecture for a two day visit that was designed to show unity, trust, and a shared vision for the future. Even though Takaichi is a conservative and Lee is from the left, both see the same challenge. China is becoming more aggressive in trade, technology, and military pressure, and both Japan and South Korea believe they are stronger when they face it together.
A Visible Show of Unity
Takaichi and Lee made a point of meeting in public and speaking warmly about one another. They highlighted their close relationship with the United States and their shared concerns about regional security, supply chains, and North Korea’s nuclear weapons.
Lee described the moment in clear terms. “As we navigate a complex and unsettled international order and strive toward a new and better future, I believe that cooperation between South Korea and Japan is more important than ever, more important than anything,” he said. “This meeting in Nara between us holds particularly profound significance.”
Takaichi also spoke about the growing partnership. “There will be further talks between relevant departments to deepen cooperation, both in terms of the economy and economic security, in ways that are strategic and beneficial to both sides,” she said during a joint press conference. She added that the two leaders held in depth discussions on supply chain cooperation.
They also agreed to expand cooperation in what Lee called a future oriented way. He said the two countries exchanged views on both regional and global issues and decided to move forward together.
From Old Disputes to New Cooperation
The warmth between Tokyo and Seoul is striking because their relationship was deeply damaged only a few years ago. In 2019, they fought a trade war after Japan limited exports of key technology materials to South Korea. Old anger over Japan’s occupation of Korea from 1910 to 1945 came back into public debate. South Korea even threatened to end an intelligence sharing agreement with Japan.
Things began to change in 2022 when both countries restarted high level diplomacy. Rising Chinese pressure and President Trump’s trade policies made cooperation more important than old arguments. Even after new leaders came into office, the momentum continued.
Andrew Yeo of the Brookings Institution explained why the shift has lasted. “The relative steadiness of Korea Japan relations to date reflects how profoundly the geopolitical environment has changed,” he said.
China’s Growing Pressure
China has become the main force pushing Japan and South Korea together. Beijing was furious after Takaichi said in November that if China attacked Taiwan, Japan could be pulled into a conflict to defend itself or its allies. China considers Taiwan a breakaway province and has vowed to take it by force if necessary.
After those remarks, China hit Japan with a wave of punishment. It canceled flights, tightened export controls on goods that could be used by the military, and began cutting off supplies of rare earths and high tech magnets that Japanese companies need.
China also tried to pressure South Korea to take its side. When Lee visited Beijing last week, Chinese officials urged him to join them against Japan. The official Chinese statement said the two countries should “join hands” to defend the outcome of World War II and resist what Beijing claims is a revival of Japanese militarism.
Lee acknowledged China’s position on Taiwan by saying he respects the one China policy, but he did not agree to turn against Japan. Instead, he traveled straight from Beijing to Nara to meet Takaichi, showing where South Korea’s true priorities lie.
China sees the growing unity between Japan and South Korea as a direct threat. Together with the United States, they form a powerful group that can resist Chinese pressure on trade, technology, and security.
Rintaro Nishimura of The Asia Group explained it plainly. “It is never a good thing for China when Japan, Korea and the U.S. are on the same page,” he said.
That is exactly what China fears most. Japan and South Korea host large numbers of US troops and take part in trilateral military exercises. They are also coordinating on supply chains and critical minerals, which limits China’s ability to use its economic power as a weapon.
Japanese Finance Minister Satsuki Katayama has been talking with other advanced economies about securing critical minerals, driven by fears that China will use its control of rare earths to hurt Japan’s economy. Defense Minister Shinjiro Koizumi is also meeting with US officials to strengthen security ties.
A Clear Shift in the Region
Supporters of closer ties say the moment demands action. Lee said the world is facing unprecedented change driven by new technology and shifting power. “Deepening and broadening cooperation between our two nations is a historical imperative we can no longer delay,” he said.
Takaichi agreed that both countries have a responsibility to the region. “Both countries should work together to play a role in regional stability,” she said, and she expressed hope to visit South Korea soon.
Japanese scholar Ayumi Teraoka added that outside forces are pushing the two countries together. “The deteriorating security environment in the Indo Pacific makes it even more necessary for these leaders to collaborate,” she wrote. “Washington’s renewed unpredictability and waning engagement in multilateral forums require Japan and South Korea to work together to sustain regional public goods and protect their interests.”
Former US Ambassador to South Korea Kathleen Stephens praised how Seoul is handling the difficult balance. “Seoul’s choreography of summitry with Washington, Tokyo, and Beijing has been masterful,” she said. “But the real challenges will come when real choices have to be made.”
While Lee still says China and Japan should resolve their differences through dialogue, the reality is that Beijing’s actions are driving Tokyo and Seoul closer together. China’s export controls, harsh rhetoric, and pressure over Taiwan have made it clear that it is willing to use both economic and political force.
At the same time, Japan and South Korea are showing that they are ready to face those challenges side by side. Their meeting in Nara was not just about good manners or ceremony. It was a clear signal that in a colder relationship with China, warmth between Tokyo and Seoul is becoming a strategic necessity.
As China pushes harder, Japan and South Korea appear more determined than ever to stand together.
FAM Editor: As security alliances develop, trade routes will adjust, cultures will adjust, closeness becomes closer. This is an evolution that will find many countries cooperating to stand against China if China decides that it needs to invade Taiwan.
