Tokyo, December 19, 2025
Table of Contents
A surprising diplomatic alignment is taking shape between Japan and South Korea, despite ancient tensions and China’s growing influence in the region.
- The relationship between Japan and South Korea,once deeply strained,is showing signs of resilience amid increasing regional pressure from China.
- New leadership in both countries-Prime Minister Sanae Takaichi in Japan and President Lee Jae-myung in South Korea-presents an unlikely but potentially effective partnership.
- China is actively attempting to pressure Japan, mirroring tactics used against south Korea in the past, highlighting the strategic importance of the japan-South Korea alliance.
- Despite historical grievances, pragmatic considerations and shared security concerns are driving a cautious but growing cooperation between Tokyo and Seoul.
The fragile but substantive thaw in relations between Japan and South Korea is being tested as both nations navigate a more assertive China,and a shifting geopolitical landscape. The two U.S. allies are finding themselves in a position to potentially counter Beijing’s influence, a dynamic that began to emerge in 2022 after a period of intense bilateral friction.
What factors are driving the renewed focus on cooperation between Japan and South Korea? The increasing muscle-flexing of China in the region is a primary catalyst,forcing a reassessment of strategic priorities.
China’s Pressure Campaign
In November, beijing launched a pressure campaign against Japan following remarks by Prime Minister Takaichi suggesting tokyo might intervene militarily if China were to attack or blockade Taiwan. The response was swift: China suspended seafood imports from Japan, canceled Japanese concerts and movie releases, and discouraged its citizens from traveling to Japan. The Japanese Defense Ministry also reported instances of Chinese fighter aircraft locking their radar onto Japanese planes-a tactic reminiscent of similar actions taken against south Korea in 2016-17 after Seoul agreed to host the U.S. missile defense system,THAAD.
South Korea has, so far, maintained a neutral stance in response to China’s pressure, but the parallels to its own experience with Beijing’s coercion are not lost on Seoul. The historical context is crucial: under previous administrations, notably that of Ye and Prime Minister Shinzo Abe aimed to resolve the comfort women issue “finally and irreversibly,” but it was discredited by the subsequent progressive administration of Moon Jae-in in 2017, shattering Japan’s trust.
By the time the conservative Yoon Suk-yeol became president in 2022 and sought rapprochement with Tokyo, Japanese officials were wary, having learned that agreements with South Korean conservatives often lacked broad public support and could be easily overturned by subsequent progressive administrations. Encouraged by the Biden administration, Yoon and then Prime Minister Fumio Kishida restored shuttle diplomacy, intelligence sharing, and chip component exports, culminating in a joint statement at Camp David in 2023 that committed the three nations to consultation in the event of a regional contingency, including a potential Chinese invasion of Taiwan.
managing expectations and Building Momentum
Upon Takaichi’s inauguration in October,the South Korean left expressed apprehension about her right-wing policies. Similarly, when lee won the election in June after Yoon’s impeachment, many in Japan questioned his commitment to cooperation, given his past criticisms of Japan’s historical actions and its release of treated wastewater from the Fukushima nuclear power plant in 2023. Despite Lee’s initial conciliatory tone-choosing Tokyo as his first foreign destination-doubts remained about his long-term commitment.
Though, early interactions between Takaichi and Lee have been surprisingly positive. At the Asia-Pacific Economic Cooperation forum in October, Takaichi bowed to the South Korean flag, a gesture widely covered in South Korean media. Lee, in turn, told a domestic audience that he was “no longer worried” about having Takaichi as his counterpart, a sentiment echoed by Japanese media. Lee is reportedly considering a visit to Tokyo in January 2026.
By deepening cooperation across ideological lines and carefully managing expectations, Tokyo and Seoul have a rare chance to forge an alignment that can withstand future political shifts.
