Though North Korean ballistic missiles account for only a small portion of Russia's missile strikes they carry a large warhead of up to one tonne and have a range of up to 800 km, the military source said. The Iskander-M, an equivalent Russian missile, carries a smaller payload and has a shorter range of 500 km.

North Korean soldiers fighting alongside Russia's army in the Kursk region appear to have suspended combat operations last month, South Korea's spy agency told AFP Tuesday, coming after Ukraine claimed the soldiers had been pulled from the front line after facing heavy losses.