North Korean troops have not been seen on the frontlines in Russia’s Kursk region for several weeks, a Ukrainian military official said Friday, amid reports of mass casualties among Pyongyang’s forces.

Ukraine’s special operations forces said on Friday that North Korean troops have not been spotted on the battlefield in Russia’s Kursk region for about three weeks, indicating they may have withdrawn after sustaining heavy losses,

North Korea sent its best troops to aid Russia in its war against Ukraine. But after months of suffering severe losses, they have been taken off the front line.