The top diplomats of South Korea, the United States and Japan held three-way talks on the sidelines of the Asia-Pacific Economic Cooperation summit in San Francisco on Tuesday, as they are stepping up cooperation to address North Korean threats and other regional and global issues.

Foreign Minister Park Jin, US Secretary of State Antony Blinken and Japanese Foreign Minister Yoko Kamikawa met trilaterally less than two months after they held brief talks on the margins of the UN General Assembly in New York.

Their meeting came as Washington is seeking greater cooperation from regional allies and partners in the midst of multiple security challenges, including the war between Israel and the Hamas militant group and Russia's protracted war in Ukraine.

"Looking around the world, there is so much work for us to do together," Blinken said, noting that the agenda for Tuesday's meeting included North Korea's military cooperation with Russia, support for Ukraine and other regional and global issues.

Park noted that cooperation among the three nations has been reaching "unprecedented heights" since the summit between President Yoon Suk Yeol, US President Joe Biden and Japanese Prime Minister Fumio Kishida at Camp David in August.

"The agreements among our leaders are, one by one, bearing fruit," he noted, pointing to the arrangements from the trilateral summit, which include holding various trilateral meetings on various topics, including space, on a regular basis.

He added, "The rules-based order is facing multiple challenges in this poly-crisis era. Strengthening cooperation among like-minded countries is more important than ever."

Atop their agenda was expected to be burgeoning military relations between North Korea and Russia, which Seoul, Washington and Tokyo see as a violation of multiple UN Security Council resolutions banning any weapons trade with Pyongyang.

The three diplomats could also discuss joint responses in the event of Pyongyang pressing ahead with its stated plan to make a third attempt to put a military reconnaissance satellite into orbit.

Blinken was expected to use the three-way session to explain the agenda for the high-stakes summit between President Joe Biden and Chinese President Xi Jinping, which is slated to take place in San Francisco on Wednesday.

Senior US officials have said that the summit would cover a "whole range" of issues, including Sino-US relations, North Korean threats, Taiwan, the instability in the Middle East and Russia's war in Ukraine.

Seoul and Tokyo have watched developments in the relations between the world's two largest economies due to the implications for their diplomacy, security and trade.

Last week, Blinken visited Tokyo and Seoul on a multi-nation trip, during which he highlighted America's "intense focus" on the Indo-Pacific despite the Israel-Hamas war and Russia's war in Ukraine. (Yonhap)