South Korea's defense chief has suggested there is a high possibility that North Korea will send troops to Ukraine to support Russian forces.

North Korea has been providing Russia with shells and missiles, underscoring their deepening military cooperation.

South Korean Defense Minister Kim Yong-hyun told a parliamentary committee on Tuesday that the relationship between the two countries has become as close as a military alliance.

Asked by a lawmaker if there is a possibility of North Korea deploying troops to Ukraine, Kim said it is "highly likely."

Ukrainian media reported on Friday that six North Korean officers were killed in a Ukrainian missile strike in a Russian-controlled area in eastern Ukraine.

Kim said the report is probably true under the circumstances.