Russia attacked the Ukrainian capital Kyiv with a sophisticated combination of missiles and drones for the first time in 73 days on Wednesday, authorities reported, as the Pentagon said most of the North Korean troops sent to help Moscow’s war effort are fighting to drive Ukraine’s army off Russian soil in the Kursk border region.

"Today I can confirm that over 10,000 (North Korean) soldiers have been sent to eastern Russia, and most of them have moved to the far western Kursk Oblast, where they have begun engaging in combat operations with Russian forces,

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.

"The deepening military cooperation between Russia and North Korea is a threat to both the Indo-Pacific and Euro-Atlantic security," NATO Secretary-General says.

The Pentagon said on Monday that it is concerned Russia could use the soldiers to support its military operations against Ukraine in Kursk.

Kyiv "could secure mass surrender and defection among North Korean soldiers if proactive psychological warfare is mobilized," said one North Korean defector.

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.

Former North Korean soldiers, operating under the name Defectors' Propaganda Corps, have delivered materials to Ukraine aimed at encouraging North Korean military personnel serving in the Russian army to desert.