A dispute is escalating between Ukraine and South Korea. The root of the disagreement flows from Ukraine’s capture of two North Korean soldiers who were fighting alongside Russia in January 2025. Both soldiers later expressed a desire to relocate to South Korea. After negotiations, they were quietly transferred to Seoul in September. All was fine.
Then Ukrainian President Volodymyr Zelensky announced the soldiers’ transfer during his speech to the U.N. General Assembly late last month. It turned what Seoul regarded as a sensitive intelligence and humanitarian operation into a public diplomatic issue.
South Korean President Lee Jae Myung said that Ukraine and South Korea had agreed to keep the transfer confidential because publicity could endanger the soldiers, their families in North Korea, and complicate diplomacy on the Korean Peninsula. Kyiv initially disputed the existence of such an agreement. But South Korean intelligence officials later told lawmakers that Ukraine had, itself, first requested secrecy. Seoul demanded an apology, while Ukrainian Foreign Minister Andrii Sybiha described the affair as a diplomatic misunderstanding.
Still, this disagreement only highlights a widening gap between Seoul and Kyiv over a much larger question. Namely, that Ukraine increasingly sees North Korea’s participation in the war as proof that European and Korean security have become part of the same conflict. In contrast, South Korea remains wary of risking a deeper confrontation with either North Korea or Russia.
The bilateral relationship has also been strained by energy trade. Ukraine’s sanctions adviser, Vladyslav Vlasiuk, said more than 176,000 tons of petroleum products were shipped from South Korean ports to Russia in July and August, accounting for about 31% of Russia’s fuel imports in August. These transfers came just as Ukrainian strikes were hitting Russian refineries. Seoul disputed the implication that South Korea was supplying Russia and said it was investigating the shipments. South Korea still depends on Russian liquefied natural gas under long-term contracts and has sought sanctions exemptions to protect those supplies.
This is not to say that South Korea is on Russia’s side. On the contrary, South Korea has supported Ukraine since Russia’s full-scale invasion. It has joined sanctions against Moscow and provided reconstruction funding and other assistance to Kyiv. And while South Korea has not provided lethal assistance to Ukraine, it manufactures artillery ammunition, air-defense systems, missiles, and other weapons Ukraine desperately needs.
For a period under former president Yoon Suk Yeol, South Korean policy appeared more flexible. After Russian President Vladimir Putin and North Korean leader Kim Jong Un signed a mutual-defense treaty in 2024, Seoul said it would reconsider supplying arms to Ukraine. North Korea’s deployment of troops to Russia gave the debate greater urgency. South Korean officials discussed sending personnel to observe North Korean tactics, while Ukrainian officials pressed Seoul for air-defense systems and other military equipment.
In contrast, Lee has taken a more cautious approach. He fears that direct military support for Ukraine could encourage Russia to accelerate transfers of missile, satellite, air-defense, or other advanced technology to North Korea.
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The difficulty with Lee’s calculation is that Russia has already greatly expanded its military-technical cooperation with Pyongyang. South Korean and Western officials have repeatedly warned that this relationship is helping North Korea improve its military capabilities, and Ukraine now believes Moscow has also shared technology related to jet-powered drones. North Korean forces are also gaining experience in a war shaped by drones and rapid adaptation.
Seoul has been careful throughout the war, but Moscow has shown no comparable restraint. That leaves Seoul protecting against an escalation that already exists. The dispute over the two prisoners exposes a larger problem. South Korea is trying to preserve some distance from the war, but the transfer itself showed how difficult that has become.