North Korea is expanding a weapons plant that manufactures missiles used by Russia against Ukraine, according to new research from a US-based think tank.

"For the Republic of Korea, these actions pose a serious threat, as North Korean troops are gaining combat experience, which could present additional security challenges in the region in the future," Defense Minister Rustem Umerov said following his visit to South Korea.

South Korea’s president has met a visiting Ukraine delegation and called for a joint response to the threat posed by North Korea’s recent dispatch of more than 10,000 soldiers to support Russia’s war against Ukraine.