South Korea's military suspects North Korea is preparing to send more troops to Russia to fight Ukrainian forces, following reports of heavy casualties among North Korean soldiers due to a lack of modern combat training.

Leader Kim Jong Un pledged to pursue "sustained countermeasures," citing security ties between the U.S. and its regional allies.

Kim Jong Un said an elevated U.S. security partnership with South Korea and Japan poses a grave threat to his country and vowed to further bolster his nuclear weapons program, state media reported Sunday.

The warning came after Kim accused the US of escalating tensions on the Korean Peninsula through its alliance with South Korea and Japan.View on euronews

North Korean leader Kim Jong Un has vowed to bolster his nuclear weapons program in response to the U.S.’s enhanced security partnership with South Korea and Japan. Last year, the U.S. expanded bilateral military exercises with South Korean and trilateral training with South Korea and Japan.