Zelenskyy revealed during an address to the United Nations General Assembly last week that Ukraine had recently transferred the two North Korean soldiers to South Korea after they were captured while fighting alongside Russian forces. The soldiers were captured in Russia’s Kursk region in January 2025.

South Korean President Lee Jae Myung subsequently expressed regret over the disclosure, saying Seoul and Kyiv had agreed not to make the transfer public because of diplomatic, security and humanitarian concerns.

Ukraine has disputed Seoul’s account, with a Ukrainian presidential source denying that such a confidentiality agreement existed. South Korean officials have rejected that denial.

Seong Ghi-hong, a senior presidential adviser for public relations, said Sunday that Seoul expressed “strong regret” over what it described as Ukraine’s unilateral disclosure and subsequent denial of the confidentiality agreement.

South Korea said the agreement was intended in part to protect the two soldiers and their relatives in North Korea. Seoul also said Ukraine had its own concerns that public disclosure could prompt criticism over giving up a potential opportunity to exchange the North Koreans for Ukrainian prisoners held by Russia.

The dispute escalated Monday when South Korea’s Foreign Ministry summoned Ukraine’s acting ambassador in Seoul to formally protest the disclosure and demand an explanation and apology. The Ukrainian diplomat said Seoul’s position would be conveyed to Kyiv.

The two prisoners were among thousands of North Korean troops sent to support Russia’s war effort. While still in Ukraine, both men had expressed a desire to resettle in South Korea.

The disagreement has introduced new tensions into relations between Seoul and Kyiv, with South Korean officials warning that the episode has damaged trust between the two governments.