Ukraine's military intelligence service said on Thursday that the first North Korean units trained in Russia had been deployed in the Kursk region, a Russian border area where Ukrainian forces staged a major incursion in August.
The Kremlin has previously dismissed reports about the North's troop deployment as "fake news". But Russian president Vladimir Putin said on Thursday that it was Moscow's business how to implement a partnership treaty with Pyongyang.
Putin did not deny that North Korean troops were currently in Russia.
"The first units of the military from the DPRK, which were trained at the eastern Russian training grounds, have already arrived in the combat zone of the Russian-Ukrainian war. In particular, on October 23, 2024, their presence was recorded in the Kursk region," the Ukrainian intelligence agency said in a statement.
It said a total of around 12,000 North Korean troops, including 500 officers and three generals, were already in Russia, and training was taking place on five military bases.
Russian Deputy Defence Minister Yunus-Bek Yevkurov was appointed responsible for overseeing the training of North Korean military, the agency said.
Ukraine has earlier called on its allies to respond firmly to North Korean involvement into war by imposing new sanctions and further isolating Pyongyang.
On Wednesday, the U.S. said it had seen evidence that North Korea has sent 3,000 troops to Russia for possible deployment in Ukraine.
South Korea's National Intelligence Service said the North had shipped 3,000 troops, including special forces, to Russia's Far East for training and acclimatising at military bases there, probably to be deployed for combat in the war.
Moscow and Pyongyang ties grew deeper after Russia invaded Ukraine in February 2022 and they signed a comprehensive strategic partnership deal in June.
Putin has said the treaty included a mutual assistance clause for each side to help the other repel external aggression.
North Korea has supplied ballistic missiles and ammunition rounds to Russia for its war in Ukraine, Kyiv and its Western allies say. Pyongyang has denied this.
