A captured North Korean soldier is seen in this photo posted on Ukrainian President Volodymyr Zelenskyy's X, Saturday (local time). Zelenskyy said two soldiers were captured in Russia's Kursk region and are being interrogated in Kyiv. Yonhap

Ukrainian forces captured two North Korean soldiers on a battlefield in Russia's western Kursk region, South Korea's National Intelligence Service (NIS) confirmed on Sunday.

The soldiers testified there were "considerable losses" of North Korean troops, according to the NIS.

The NIS' confirmation came hours after Ukraine's President Volodymyr Zelenskyy said Saturday (local time) in a post on Telegram that its forces captured two soldiers alive in the border region, and they are being investigated by the Security Service of Ukraine (SBU) in Kyiv.

It is the first time that North Korean troops have been captured during combat operations and interrogated. About two weeks ago, another North Korean soldier was captured but died a day later due to serious injuries.

According to the NIS, the Ukrainian military captured them on Thursday. Both sustained injuries that were not life-threatening.

One of them testified that he arrived in Russia in November, where they received one week of military training before being deployed to the frontline. He said he had thought he came to Russia for training only, learning only after his arrival that he had been dispatched to the war.

He further said troops suffered major losses during battles, adding he had been without food and water for four to five days before being captured, according to the NIS.

The spy agency said it is cooperating closely with the SBU and will continue sharing intelligence. It also implied its own involvement in interrogating the soldiers, particularly by providing translation assistance, as reported by Ukraine media and other global news agencies which said a South Korean working for the NIS is helping with translation.

A captured North Korean soldier is seen in this photo posted on Ukrainian President Volodymyr Zelenskyy's X, Saturday (local time). Zelenskyy said two soldiers were captured in Russia's Kursk region and are being interrogated in Kyiv. Yonhap

According to the media, the two were born in 2005 and 1999, respectively.

The younger soldier, a rifleman, carried a forged Russian military ID card identifying him as a 26-year-old from Siberia's Tuva Republic. He told investigators he had received the ID during joint training with Russian forces in late 2024.

The older soldier, who identified himself as a sniper, is unable to speak due to a jaw injury and has been communicating with investigators via writing.

Medical staff confirmed that both are receiving treatment for their injuries.

Zelenskyy said it has been difficult to capture North Koreans alive, because "Russians and other North Korean soldiers finish off their wounded" to hide "evidence of North Korea's involvement in the war."

Ukrainian Foreign Minister Andrii Sybiha emphasized that the soldiers are regular members of North Korea's armed forces, not mercenaries.

It is expected the captured soldiers could provide meaningful intelligence on the extent of North Korea's military support for Russia.

The ultimate fate of the captured soldiers remains uncertain. If Russia claims them as part of its armed forces, they could be classified as prisoners of war (POW) under the Geneva Conventions and repatriated. However, if both Moscow and Pyongyang deny their affiliation, they could be deemed unlawful combatants, complicating their status under international law.

Some have speculated that the soldiers might seek asylum in South Korea, though such an outcome would face significant diplomatic and logistical challenges. Zelenskyy previously suggested that North Korean POWs could be exchanged for Ukrainian soldiers held by Russia.

North Korea reportedly began deploying troops to Russia's Kursk region in late 2024, with an estimated 11,000 personnel involved.