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 Korean forces have been pulled off the frontlines in the Kursk region after suffering heavy losses in combat, The New York Times reports. According to Ukrainian and US officials, North Korean soldiers who had been fighting alongside Russian forces against Ukraine were withdrawn after sustaining significant casualties.

The spokesman did not say how long that front line was. And while this is not the full picture, it does suggest significant North Korean casualties. Separately, the New York Times also reported that the North Koreans had been pulled off the front lines.