North Korean soldiers sent to fight in Russia's Kursk region haven't been seen for several weeks, reports say.

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engaged in combat since mid-January, South Korea's spy agency told AFP on Tuesday, after Ukraine claimed they had been withdrawn following heavy losses.

North Korean soldiers had been missing from combat, fueling speculation they were pulled back after taking heavy losses.

This is almost certainly primarily due to heavy losses sustained during attacks against Ukrainian-held positions.” Reports differ on the scale of the losses but one put them as high as 4,000 North Korean soldiers killed or wounded.

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.

South Korea's National Intelligence Service has reportedly confirmed that North Korea has withdrawn its troops from the frontline in Russia's Kursk region after entering the war late last year