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

Pyongyang is believed to have sent some 11,000 soldiers to help Putin’s army recapture a swathe of the Kursk region of Russia which Ukrainian forces seized in a surprise attack last summer. The Russian military has been gradually gaining ground in the attempt to force Ukrainian units out of Kursk.

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engaged in combat since mid-January, South Korea's spy agency told AFP on Tuesday, after Ukraine claimed they had been withdrawn following heavy losses.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 president highlights incursion into Kursk region, alleged Russian losses, London's continued support in talks with UK foreign secretary - Anadolu Ajansı

Over recent weeks more than 20 North Korean KN-23 ballistic missiles have struck Ukraine, according to Reuters. These missiles, capable of hitting targets up to 500 miles away, have overwhelmed Ukraine’s already depleted air defence systems.

A military source, who requested anonymity to discuss sensitive information, described a marked improvement in the precision in all the more than 20 North Korean ballistic missile

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.