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.

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.

North Korean troops fighting for Russia have been pulled from the front line for extra training after crude tactics led to massive casualties.

North Korean troops have been pulled back from the frontline amid devastating losses, according to Ukrainian and American officials. Kim Jong Un ’s forces have not been seen on the battlefield for around three weeks, Ukrainian special forces said, according to the New York Times.