Ukraine is fighting a war against two nuclear weapons countries: Russia, a signatory of the non-proliferation treaty, and North Korea, which is not. Since 2014, Moscow has been undermining the logic and letter of the Nuclear Non-Proliferation Treaty (NPT) with its nuclear posturing.

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 previously fighting alongside Russia's army on the Kursk front line appear not to have been engaged in combat since mid-January, South Korea's spy agency told AFP on Tuesday, after Ukraine claimed they had been withdrawn following heavy losses.

Ukrainian special operations forces have given an insight into the brutal, near-suicidal tactics of the North Koreans they have faced in intense fighting in the Russian border region of Kursk.

It is time to examine not only the effects and effectiveness of North Korean troops in combat, but the wider implications for international security and conflict management.

A Ukrainian news outlet has published a video showing the capture of a North Korean soldier, as South Korea's spy agency said Kim Jong Un has pulled troops from Russia's Kursk region. Newsweek has contacted the Russia's Foreign Ministry for comment.