The leaders of Japan and South Korea promised to turn the page on years of animosity at a meeting on Thursday, putting aside their difficult shared history and pledging to work together to counter regional security challenges.
The summit between South Korea's Yoon Suk Yeol and Japan's Fumio Kishida in Tokyo - the first visit to Japan by a South Korean president in 12 years - highlighted how the two US allies have been brought closer by North Korea's frequent missile launches and growing concern over China's more muscular role on the international stage.
The urgency of the regional security situation - and the threat posed by North Korea - were underscored hours before Yoon's arrival, when North Korea fired an intercontinental ballistic missile that landed in the sea between the Korean peninsula and Japan.
Washington hailed the summit, calling Japan and South Korea "indispensable allies".
"Improved ties between Seoul and Tokyo will help us embrace trilateral opportunities to advance our common regional and international priorities, including our vision for a free and open Indo-Pacific," a State Department spokesperson said. "We applaud Prime Minister Kishida and President Yoon for taking this positive step forward."
Seoul-Tokyo tensions have long undercut US-led efforts to present a united front against China and North Korea.
"The fact that President Yoon visited Japan and the two countries held a bilateral meeting - rather than on the sidelines of an international forum - that alone should be commended as a possible turning point," said Hideki Okuzono, an international relations professor at the University of Shizuoka.
Christopher Johnstone, formerly East Asia director of US President Joe Biden's National Security Council and now with Washington's Center for Strategic and International Studies, said there was reason for optimism the breakthrough would prove durable, given shared concerns about China snd North Korea.
"Both Yoon and Kishida are early in their tenures, which increases the likelihood that the new tone in bilateral relations will solidify into a stronger foundation for bilateral ties," he said. "The fact that Yoon and Kishida own this breakthrough gives them motivation to see that it endures.”
The two countries agreed to drop an almost four-year trade dispute on some high-tech materials used for chips, something that dogged their relationship even as the political importance of semiconductors, and securing their supply, has increased.
They also agreed to revive regular bilateral visits and to restart a security dialogue suspended since 2018. Yoon also declared a "complete normalisation" of an intelligence-sharing pact, known as GSOMIA, which Seoul threatened to pull out of in 2019.
The relationship has been strained by a dispute over wartime history, including over compensation of South Koreans forced to work under Japan's 1910-1945 occupation, as well as the issue of women and girls forced into Japanese military brothels.
"Today was a good day for shared interests, shared values and shared goals," US Ambassador to Japan Rahm Emanuel said on Twitter.
Signs of a breakthrough came last week when Seoul announced a plan for its companies to compensate former forced labourers.
"This week Tokyo saw its cherry blossom trees blooming a little earlier than usual," Kishida said as he faced Yoon across a table.
"I'm very happy to have this opportunity to start a new chapter of a forward-looking future of Japan and South Korea relations on this day when we can feel the arrival of spring."
Yoon said North Korea's missile launch had shown the "grave threat" to international peace and stability.
"Today's meeting with Prime Minister Kishida has a special meaning of letting the people of our two countries know that South Korea-Japan relations, which have gone through difficult times due to various pending issues, are at a new starting oint," Yoon said.
Japan will remove curbs on some exports to South Korea of critical materials for smartphone displays and chips imposed in 2019 while Seoul will drop a World Trade Organization (WTO) complaint against Tokyo, officials from both sides said.
The attempt for closer ties brought a rebuke from China, whose foreign ministry said it opposed the attempt by certain countries to form exclusive circles.
Scepticism in South Korea
Yoon faces scepticism at home. In a poll by Gallup Korea published Friday, 64% of respondents said there was no need to rush to improve ties with Japan if there was no change in its attitude, and 85% said they thought the Japanese government was not apologetic about Japan's colonial history.
Nevertheless, economic ties are strong. IMF data shows the two countries were each other's fourth-largest export markets in 2021. Japanese exports to South Korea totalled US$52 billion (about RM233 billion) and South Korean exports to Japan US$30 billion.
Japan's biggest business lobby, Keidanren, said it and its South Korean counterpart, the Federation of Korean Industries, agreed to launch foundations aimed at "future-oriented" bilateral relations.
However, in a fresh reminder of the long-running tensions, two South Korean victims of wartime forced labour filed a lawsuit, seeking compensation from Japan's Mitsubishi Heavy Industries, their representatives said on Thursday.
Park Hong-keun, floor leader of South Korea's main opposition Democratic Party, said Yoon should seek a true apology and resolution from Japan on forced labour issues from his trip.