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.

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.

North Korean missiles used by Russia in attacks on Ukraine since December have become more accurate, Reuters reported on Feb. 6, citing sources familiar with the matter. Analysts believe North Korea is using the battlefield as a testing ground for its missile technology,

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

Experts say Pyongyang’s advancing missile technology raises global security risks and threatens regional stability.