US President Joe Biden and the leaders of Japan and South Korea said Friday they saw a "new chapter" of close three-way security cooperation as the Asian allies joined a first-of-a-kind summit that has already rattled China. US President Joe Biden(Bloomberg)

Going tieless at the bucolic Camp David presidential retreat, Biden praised the "political courage" of South Korean President Yoon Suk Yeol and Japanese Prime Minister Fumio Kishida in turning the page on historical animosity.

"Your leadership, with the full support of the United States, has brought us here because each of you understands that our world stands at an inflection point," Biden told a joint news conference in the wooded hills outside Washington.

Biden insisted the summit was not about China, which has been flexing its muscle both at home and in Asia under President Xi Jinping, including with major exercises around self-ruling Taiwan.

But in a joint statement, the three leaders said they opposed the "dangerous and aggressive behavior" of China in maritime disputes in the East and South China Sea.

"We strongly oppose any unilateral attempts to change the status quo in the waters of the Indo-Pacific," it said.

The two US allies largely see eye to eye on the world -- and together are the base for some 84,500 US troops -- but such a summit would have been unthinkable until recently due to the legacy of Japan's harsh 1910-1945 occupation of the Korean peninsula.

But Yoon, taking political risks at home, has turned the page by resolving a dispute over wartime forced labor, and is now calling Japan a partner at a time of high tensions with both China and North Korea.

Yoon said he hoped to be "forward-looking" and called the summit a "historic day" in bringing a "firm institutional basis" to the three nations' joint relationship.

The three leaders also agreed to a multi-year plan of regular exercises in all domains, going beyond one-off drills in response to North Korea, and made a formal "commitment to consult" during crises, with Biden saying they would open a hotline.

The leaders also agreed to share real-time data on North Korea and to hold summits every year.

Camp David marks the first time the three countries' leaders have met for a standalone summit, not on the sidelines of a larger event, and is the first diplomatic event since 2015 at the resort, which is synonymous with Middle East peacemaking.

- 'You can never become a Westerner' -

Even if Biden said the summit did not target China, Rahm Emanuel, the blunt-speaking US ambassador to Japan, took another tone when he previewed the meeting, saying the three nations were defying China with the United States showing, "We are the rising power; they are declining."

Chinese Foreign Minister Wang Yi urged the two economically developed Northeast Asian democracies instead to work with Beijing to "revitalize East Asia."

"No matter how blond you dye your hair or how sharp you shape your nose, you can never become a European or American, you can never become a Westerner," he said in a video shared on official media.

"We must know where our roots lie," he said.

But China's pressure tactics have led to a sharp deterioration in its favorability in Japan and South Korea, which have traditionally been more discreet than the United States in their comments.

Tensions have also risen with North Korea, which has launched a volley of missiles in recent months and is feared to respond to the summit with new action.

The leaders' joint statement renewed a call on North Korea to give up its nuclear weapons and urged all nations to enforce sanctions.

As the Camp David summit opened, North Korea said it had scrambled jets in response to what it called a US spy plane's incursion.

- Global allies -

The summit also set its focus beyond North Korea and even Asia.

Tokyo and Seoul have offered a major boost to Ukraine as major non-Western powers joining pressure against Russia's invasion.

Kishida said greater cooperation with South Korea was "almost inevitable" in light of the "crisis" in the world order.

"Due to Russia's aggression of Ukraine, the international order is shaken from its foundation. The unilateral attempt to change the status quo by force in the East and South China Seas are continuing and the nuclear and missile threats of North Korea are only becoming even greater," Kishida said.

The summit aims to institutionalize three-way cooperation to make it difficult for any reversal by a future leader -- a South Korean president who again seizes on hostility with Japan or, potentially, a return of Donald Trump, who has disparaged US troop commitments overseas as wasteful.

To the surprise of many observers, Yoon's embrace of Japan has drawn relatively muted protests at home.

Yoon, a conservative, has quickly become a close US ally, with Biden welcoming him for a rare state visit in which the South Korean leader regaled the audience by singing "American Pie."

But Yoon is constitutionally prohibited from serving more than a single term, which ends in 2027.

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