South Korea’s spy agency reported that North Korea has sent more troops to Russia in response to heavy casualties suffered by soldiers deployed on the Russian-Ukraine fronts.

The National Intelligence Service mentioned in a brief statement that it is working to establish the exact number of additional troops sent by North Korea to Russia.

Additionally, the NIS stated that North Korean troops were relocated to fronts in Russia’s Kursk region during the first week of February after reportedly withdrawing temporarily from the area.

Ukrainian President Volodymyr Zelenskyy, in an address on Feb. 7, confirmed a new Ukrainian offensive in Kursk and said North Korean troops were fighting alongside Russian forces there.

North Korea has been supplying a vast amount of conventional weapons to Russia, and last fall, it sent about 10,000-12,000 troops to Russia as well, according to US, South Korean, and Ukraine intelligence officials. 

North Korean soldiers are highly disciplined and well trained, but observers say they’ve become easy targets for drone and artillery attacks on Russian-Ukraine battlefields due to their lack of combat experience and unfamiliarity with the terrain.

In January, the NIS said about 300 North Korean soldiers had died and another 2,700 had been injured. 

Zelenskyy earlier put the number of killed or wounded North Koreans at 4,000, though US estimates were lower at around 1,200.

Earlier Wednesday, South Korea’s JoongAng Ilbo newspaper, citing unidentified sources, reported that an additional 1,000-3,000 North Korean soldiers were deployed to Kursk between January and February.

South Korea, the US and their partners worry that Russia could reward North Korea by transferring high-tech weapons technologies that can sharply enhance its nuclear weapons program.

North Korea is expected to receive economic and other assistance from Russia as well.

During talks in Saudi Arabia last week, Russia and the US agreed to start working toward ending the war and improving their diplomatic and economic ties.

Ukrainian officials weren’t present at the talks.

That marked an extraordinary shift in US foreign policy under President Donald Trump and a clear departure from US-led efforts to isolate Russia over its war in Ukraine.

Observers say North Korean leader Kim Jong Un could send more troops to Russia to win further Russian assistance before the war ends.