KYIV, Ukraine (AP) — North Korean troops are suffering heavy losses in the fighting in Russia’s Kursk region and facing logistical difficulties as a result of Ukrainian attacks, Ukraine’s military intelligence said Thursday.

The intelligence agency, known under its acronym GUR, said Ukrainian strikes near Novoivanovka inflicted heavy casualties on North Korean units. It said North Korean troops also faced supply issues and even shortages of drinking water.

Ukrainian President Volodymyr Zelenskyy said earlier this week that 3,000 North Korean troops have been killed and wounded in the fighting in the Kursk region. It marked the first significant estimate by Ukraine of North Korean casualties several weeks after Kyiv announced that North Korea had sent 10,000 to 12,000 troops to Russia to help it in the almost 3-year war.

The casualty disclosure came as the Biden administration was pressing to send as much military aid as possible to Ukraine before President-elect Donald Trump takes over in January.

Russia has sought to break Ukraine’s resistance with waves of strikes with cruise missiles and drones against Ukraine’s power grid and other infrastructure.

The latest attack on Christmas morning involved 78 missiles and 106 drones, striking power facilities, Ukraine’s air force said. On Thursday, Russia attacked Ukraine with 31 exploding drones; 20 were shot down and 11 didn’t reach their target due to jamming, the Ukrainian air force said.