North Korea has started sending troops to fight with Russia in Ukraine, South Korea’s spy agency has said as Seoul warned of a grave security threat.

The allegation comes a day after Ukrainian President Volodymyr Zelensky said that he believed ten thousand North Korean soldiers could join the war, based on intelligence information.

South Korean President Yoon Suk Yeol called for a security meeting yesterday and said that the international community must respond with all available means.