US President Joe Biden and the leaders of Japan and South Korea said on Friday they saw a "new chapter" of close three-way security cooperation as the Asian allies joined a first-of-a-kind summit.

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.

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.

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. (AFP)