A couple hundred North Korean troops fighting alongside Russian forces against Ukraine have been killed or wounded during battle in the Kursk border region, a senior military official said Tuesday.

The official didn’t provide details on exactly how many have been killed, but said the North Korean forces don’t appear to be battle-hardened, which contributes to the number of casualties they’ve had. The official was providing the first significant estimate of North Korean casualties, which comes several weeks after Ukraine announced that North Korea had sent 10,000 to 12,000 troops to Russia to help it in the almost 3-year war.

The official spoke on condition of anonymity to provide a U.S. assessment of the war. The White House and Pentagon on Monday confirmed that the North Korean forces have been battling on the front lines in largely infantry positions. They have been fighting with Russian units and, in some cases, independently around Kursk.

Ukrainian and Russian forces have been in a fierce battle around Kursk, and the official said Russia has been able to take back about 20% of the territory gained there by Kyiv. They said it will be possible for Ukraine to hold ground there for some time, but it will depend on how the rest of the fight is going, including the long-range strikes that Kyiv has been launching.

(AP)