The meeting on the sidelines of the Asia-Pacific Economic Cooperation summit in Peru comes as North Korea has deployed thousands of troops to Russia to help Moscow try to claw back land in the Kursk border region that Ukraine seized earlier this year.

The president said stronger ties with South Korea and Japan are working, but did not address whether President-elect Donald J. Trump would continue his approach when he takes office in January.

US President Joe Biden told the leaders of Japan and South Korea that their coordinated efforts were essential to “countering North Korea’s dangerous and destabilizing cooperation with Russia” as they met Friday on the sidelines of the APEC Summit in Lima.