At least 30 North Korean troops, deployed to bolster Russian forces in their war on Ukraine, have been killed or wounded in Russia’s Kursk region, Ukrainian authorities said Monday, marking a significant turning point after months of speculation over what role Pyongyang’s troops might play in the war.

This is the first reported casualties since the Pentagon and Ukraine announced North Korea has sent about 10,000 troops to Russia to help it in the almost 3-year war.