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.

The soldiers appear to have been pulled back from the front lines in Kursk after suffering heavy casualties during barely a month of combat, Ukrainian officials said.

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.