South Korean President Lee Jae Myung has accused Ukrainian President Volodymyr Zelensky of breaking a confidentiality agreement. At the UN, Zelensky revealed that Ukraine had sent two captured North Korean soldiers to South Korea. It was an unusually public rebuke between two governments that have largely stood on the same side of the war. It also shows how sensitive the question of North Korean prisoners remains on the Korean peninsula.

The disclosure came during Zelensky's address to the UN General Assembly in New York on Wednesday. "Recently, we sent two North Korean prisoners of war to the Republic of Korea," he told world leaders. Remarking that such soldiers are hard to capture alive, he said one had tried to kill himself when he realised he was about to be taken prisoner. Zelensky used the case to highlight North Korea's role in the war, accusing Kim Jong Un of using his soldiers "like currency" in exchange for Russian help with missiles and drones.

Lee responded the next day on X, posting during a state visit to Mexico. He said he did not know why the Ukrainian side broke the agreement and went public, and that he found it very disappointing. He called the transfer a highly sensitive matter that could affect diplomacy, security and stability on the Korean peninsula. There had been calls to disclose the soldiers' arrival, he said, but the two sides had agreed that secrecy was the right course given the problems publicity could cause.

According to Seoul, the understanding goes back to July. Lee and Zelensky met on the sidelines of a NATO summit in Ankara and agreed to handle the prisoners on humanitarian grounds, respecting their wishes and international law. Seoul says they also agreed to keep the transfer itself confidential. A senior South Korean presidential official said Kyiv had informed Seoul in advance that Zelensky might mention the prisoners at the UN. Seoul had asked that the transfer itself not be revealed.

Kyiv sees it differently. In response to questions from South Korean media, the Ukrainian presidential office said it had disclosed only the fact of the transfer, not details of the process. It added that keeping the transfer entirely secret would have been strange.

Seoul's caution has a clear rationale. The South Korean government had refused even to confirm the prisoners' arrival, citing the safety of the soldiers and their relatives still in North Korea. South Korea considers North Koreans its citizens under its constitution and had said it would accept the men if they wished to come.

The two soldiers were captured by Ukrainian forces in Russia's Kursk region in January 2025. They are the only surviving North Korean troops publicly known to have been taken prisoner by Ukraine. Both later said they wanted to go to South Korea, in interviews and handwritten letters to North Korean defector groups. According to opposition lawmaker Yu Yong-weon, they left Ukraine last weekend, travelled through a third country and arrived in South Korea several days before the announcement.

The episode has also become a domestic political problem for Lee. The conservative opposition has attacked his government for staying silent and letting a foreign leader announce the prisoners' arrival. Analysts, meanwhile, say Zelensky's disclosure has handed Pyongyang a propaganda headache. For Seoul, the priority now is to protect two men whose defection it never wanted to publicise.