South Korea's spy agency says that North Korean forces have suffered more than 3,000 casualties while fighting alongside Russian troops.

North Korea began sending an estimated 11,000 troops to the Russian Kursk region late last year, soon after North Korean leader Kim Jong-un and Russian President Vladimir Putin agreed on a mutual defense pact designed to strengthen their alliance against what they called a US-led “Western hegemony.”

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 ballistic missiles fired at Ukraine by Russian forces since late December have been far more precise than salvos of the weapons launched over the past year, two senior Ukrainian sources told Reuters.

"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.

It also shed some light on the mindset and training of the conscripted North Korean soldiers sent to fight Russia’s war a continent away from their home. Highly disciplined, ready to die but also very young and with little battlefield experience they elicited curiosity and even some pity from the Ukrainian soldiers who captured them during two separate missions on Jan.