South Korea’s assessment comes as Ukraine’s stout defence takes a growing toll for every square kilometre Russia seizes.

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 troops, largely special ops forces, have suffered high casualties in bloody assaults not unlike other units, including prison units.

"The worst problem we are facing is the one coming from North Korea," the head of Kyiv's military intelligence agency said in the fall.

North Korean ballistic missiles have been striking targets in Ukraine with increasing accuracy in recent weeks compared to over the past year — suggesting the Hermit Kingdom is using the battlefield as a testing ground for its new tech.

The Ambassador of Ukraine to South Korea, Dmytro Ponomarenko, declared Kyiv's readiness to transfer North Korean soldiers captured in the Kursk region to Seoul. The Ambassador of Ukraine to South Korea,