Some 11,000 North Korean soldiers have already arrived in the Russian border area of Kursk, according to Ukraine.
“We see an increase in the number of North Koreans, but we see no increase in the response of our partners. Unfortunately,” Ukrainian President Volodymyr Zelensky said in his evening video message.
He said the information was based on findings from the Ukrainian intelligence services.
Kiev assumes the North Korean soldiers will soon be deployed by Russia against Ukraine.
But Zelensky described the Ukrainian advance into Kursk, which began in August, as a success, saying a “protection zone” had been created along the Russian-Ukrainian border and new Russian prisoners have been taken for potential future exchanges.
“This has greatly helped in the liberation of our people from Russian captivity,” he said.
Meanwhile observers say the Ukrainian army is suffering ever greater losses of life and material in its operations on Russian territory.