North Korean soldiers have begun fighting against Ukraine alongside their Russian allies, the US State Department said, after Pyongyang sent thousands of troops to Russia’s Kursk region to aid the Kremlin’s war efforts.

North Korean troops have begun engaging in combat operations alongside Russian forces, the U.S. State Department said on Tuesday, expressing concern that Russia had turned to North Korea for soldiers to fight in its war with Ukraine.

Nearly all would raise their hands to go, ex-military defectors explain, owing to regime loyalty, promise of higher status and a glimpse of the outside world.

Russia has amassed a large force of tens of thousands — including recently arrived North Korean troops — to carry out an assault on the Ukrainian positions in Russia’s Kursk region expected in the coming days,

Ukrainian officials expect a counteroffensive in western Russia to begin in the coming days as North Korea’s troops train with Russian forces.

Former North Korean soldiers, operating under the name Defector Propaganda Corps, have provided Ukraine with materials aimed at encouraging North Korean military personnel serving in the Russian army to defect.

The presence of North Korean soldiers alongside Russians fighting Ukraine raises many tactical and military questions, leading some analysts to wonder about their effectiveness and ultimate objectives.