History was made this weekend.
South Korean President Lee Jae-myung made his first overseas trip for bilateral diplomacy, with stops in both Washington DC and Tokyo. But unlike his predecessors, Lee didn’t visit the United States first. Instead, his first stop was Japan — South Korea’s former colonizer.
Following a bilateral summit between Lee and Japan’s Prime Minister Shigeru Ishiba, Tokyo and Seoul issued their first joint statement in 17 years; pledging deeper cooperation on AI, trade, and denuclearizing the Korean Peninsula. They also announced plans to launch a joint task force to tackle shared challenges, including aging populations and declining birth rates.
But what stood out most from this summit wasn’t what was signed. It was the shared smiles and warm words between the two leaders.
“This is our second meeting, and I feel as if we are close friends,” South Korea’s Lee said about his Japanese counterpart.
The striking shift in tone — from enmity to friendliness — is impossible to ignore.
Japan’s colonial occupation of Korea, which lasted over three decades in the first half of the 20th century, has long cast a shadow over relations. In 2023, Lee criticized his predecessor for attending a landmark summit with Japan, calling him a “puppet” of Tokyo.
But since taking office two months ago, Lee has struck a more pragmatic tone. On August 15 — South Korea’s Liberation Day from Japanese rule — he referred to Japan as “an indispensable partner” for economic growth.
This recent thaw in relations isn’t just about diplomacy — it’s largely a reflection of what’s going on west of the Pacific.
Both countries are now navigating a volatile relationship with Washington, where US President Donald Trump’s unpredictable foreign policy has thrown once-stable alliances into question. He’s imposed tariffs, demanded greater defense spending, and pushed both nations to pay more for hosting US troops. Now, South Korea’s once-ironclad alliance with the US, long a mantra of the State Department, is far from sturdy.
“The problem is that Trump’s erratic and transactional diplomacy is unnerving for everybody,” Jeffrey Kingston, a professor of Asian Studies at Tokyo’s Temple University, told CNN.
“I think after the betrayal of Ukraine, I think a lot of America’s allies are wondering what does an American security guarantee really mean?”
In Japan, Russia’s invasion of Ukraine is often seen as a cautionary tale. Former Prime Minister Fumio Kishida famously warned: “Ukraine today could be East Asia tomorrow.” Both Tokyo and Seoul are increasingly anxious about North Korea’s growing nuclear arsenal and its deepening ties with Russia in its invasion of Ukraine — where North Korean soldiers are gaining the advantage of firsthand battlefield experience.
Another looming concern for Japan and South Korea is a potential conflict over Taiwan. With China stepping up military activity near the island, fears are rising that tensions could spiral into conflict, right on their doorstep. Should that happen will the US step in? Or, as seen during the recent Alaska summit, might Trump, or a future US President, try to strike a deal with an autocratic leader — without Taiwan in the room?
Beyond security concerns, Trump’s trade war has also rattled both economies.
While Japan and South Korea have each signed deals to delay the worst tariffs, tax hikes on auto parts, steel, and aluminium are hitting hard in economies built around the auto and tech industries.
At the same time, both leaders must carefully manage ties with Beijing, the top trading partner for both countries. While neither embraces Trump’s confrontational stance toward Xi, they must still navigate Washington’s demands without compromising their economic interests.
Having already met Trump face-to-face, Ishiba may have offered Lee advice on how to manage the president’s mercurial style. During a February visit to the White House, the Japanese leader flattered Trump, saying: “I was so excited to see such a celebrity on television.” Though Ishiba’s tone shifted after months of tariff pressure and mounting domestic criticism over the lack of a signed deal. “Trump,” he later said, “is not a normal person. He’s someone who changes the rules.”
One early obstacle in this budding partnership with South Korea may be Ishiba’s likely resignation. The prime minister is under mounting pressure domestically to step down after his party lost its majority in both houses of parliament.
If he does step aside, it will be critical that he passes this rare spirit of cooperation to his successor — to ensure the newfound goodwill between the nations continues to grow.
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