SEOUL - South Korean President Yoon Suk Yeol heads to the United States on Wednesday to attend an APEC summit where he plans to seek support from other leaders for a coordinated response to growing military ties between North Korea and Russia.

This year's Asia Pacific Economic Cooperation forum takes place in San Francisco, at a time when there are concerns in the region that the conflicts in Gaza and Ukraine are distracting Western powers from focusing on hot spots in the Indo-Pacific.

Yoon has criticised what he called illegal cooperation between North Korea and Russia, describing it as a "serious threat" to regional security in an interview with the Associated Press this week. The president said he would discuss with world leaders ways to jointly respond to the development.

His U.S. trip follows back-to-back visits to Seoul by U.S. Secretary of State Antony Blinken and U.S. Secretary of Defense Lloyd Austin, where they sought to provide reassurances on Washington's commitment to the region as well as voicing concerns over growing Russia-North Korea ties.

Austin said on Tuesday China and Russia were helping North Korea expand its military capabilities by enabling it to evade sanctions, an allegation the Kremlin dismissed as "absolutely unfounded."

Washington has said North Korea is supplying military equipment to Russia for use in its war with Ukraine, while Moscow is providing technical support to help North Korea advance its military capabilities.

North Korea and Russia have denied any arms deals, though their leaders pledged closer military cooperation at their September summit.

In the latest sign of warming ties, a Russian delegation led by natural resources minister Alexander Kozlov arrived in Pyongyang on Tuesday, the North's state media reported, as the politically isolated country announced new progress in its banned ballistic missile programme.

In San Francisco, Blinken held talks with his South Korean and Japanese counterparts on Tuesday and vowed a coordinated response to the North Korea-Russia cooperation.

Yoon plans to attend the Indo-Pacific Economic Framework (IPEF) and a roundtable on technology cooperation with Japanese Prime Minister Fumio Kishida at Stanford University before heading home.

South Korea and China are also in talks for a possible meeting between their leaders, Seoul's foreign ministry said. REUTERS