Just weeks ago, relations between Ukraine and South Korea appeared stable and constructive. Shared concerns over deepening military cooperation between Russia and North Korea, the presence of North Korean troops fighting against Ukraine, and plans for economic partnership and reconstruction aid seemed to form a solid foundation. Ukrainian Foreign Minister Andrii Sybiha met his South Korean counterpart in New York, while President Zelensky held his first meeting with South Korean President Lee Jae-myung. Seoul even announced an additional $100 million in non-military assistance.

That cooperation unravelled rapidly after Ukraine transferred two North Korean prisoners of war — captured in Russia’s Kursk Oblast — to South Korea. Kyiv presented the move as a gesture of goodwill. Seoul reacted with anger. President Lee publicly accused Ukraine of violating a confidentiality agreement meant to protect the prisoners and their families still in North Korea. Ukraine denied any such agreement existed. South Korea demanded an official apology, later recalled its ambassador from Kyiv, and threatened further measures. What began as a humanitarian transfer quickly escalated into one of the most serious political crises in bilateral relations since the start of Russia’s full-scale invasion.

The sharp reaction coincides with Lee Jae-myung’s broader effort to ease tensions with North Korea and revive inter-Korean dialogue. Pyongyang, however, has shown little interest. Kim Jong Un continues to deepen his strategic alliance with Moscow, publicly supporting Russia’s war and receiving military-technical assistance in return. North Korean troops are gaining real combat experience in modern drone and combined-arms warfare — experience that South Korean experts warn could eventually alter the balance of power on the Korean Peninsula.

According to South Korean security expert Sangmin Shim of the Asan Institute, the current administration in Seoul appears overly focused on normalising relations with Russia and avoiding any friction with Pyongyang. In this context, Ukraine’s transfer of the prisoners was treated not as a positive step but as an unwelcome complication. Shim notes a clear inconsistency: South Korea has long claimed North Korean prisoners as its own citizens, yet now views their presence on its territory with anxiety. He also argues that the government underestimates the military lessons North Korean forces are acquiring in Ukraine and remains insufficiently prepared for the long-term security consequences.