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.

In this volatile and extremely uncertain landscape, South Korea has little to gain and much to lose by taking premature action that might harm its national interests.