North Korea is set to treble the number of its troops fighting for Russia along the front lines with Ukraine, sending an additional 25,000 to 30,000 soldiers to assist Moscow, according to an intelligence assessment from Ukrainian officials.

North Korea's state media showed on Monday leader Kim Jong Un draping coffins with the national flag in what appeared to be the repatriation of soldiers killed fighting for Russia against Ukraine, as the countries marked a landmark military treaty.

South Korea's spy agency says North Korea’s planned dispatch of thousands of military construction workers and deminers to Russia’s Kursk region will likely take place as early as July or August.