He initially believed that he had been sent for training, but realized, when he arrived in Russia, that he had been sent on a mission, says a source in South Korea's intelligence service about the content of interrogations that Ukraine has held with the soldiers.
The soldier also claimed that North Korean forces had suffered significant losses in the operations.
South Korea's intelligence service says that they intend to continue cooperating with Ukraine's counterpart to find out more about North Korea's participation on the Russian side in the war.
Neither North Korea nor Russia has commented on the reports of the captures.
The USA, Ukraine, and South Korea claim that North Korea has sent at least 10,000 soldiers. South Korea estimates that around 1,000 of them have been killed or injured, while Ukraine reports that it is at least 3,000.
