The transfer of two North Korean soldiers to South Korea was intended to be a quiet diplomatic success. Ukraine captured them in January 2025 while they were fighting for Russia in the Kursk region. After months of bilateral talks, they arrived in South Korea in mid-September. Ukrainian President Volodymyr Zelenskyy announced the transfer at the U.N. General Assembly on September 23. That started a spat that culminated in South Korea recalling its ambassador to Ukraine on October 8, its first protest recall since 2008. 

Seoul is still demanding acknowledgment and an apology, while Kyiv considers the matter closed. On October 20, Seoul announced plans to withdraw roughly half its embassy personnel, citing what it described as Ukraine’s failure to take constructive steps to resolve the dispute.

Ukraine had a clear strategic interest in drawing the world’s attention to North Korea’s participation in Russia’s war. Instead, the episode exposed something else: a lack of sufficiently clear ground rules for managing the sensitive political consequences of South Korea-Ukraine cooperation.

Nearly a month after Zelenskyy’s revelation, the two governments still can’t agree on what they agreed on in terms of confidentiality. Seoul says confidentiality governed the talks from the start, even though no formal nondisclosure document was signed. It says internal records support that account and that it told Kyiv before Zelenskyy’s speech not to breach the understanding. Kyiv initially denied that a confidentiality agreement existed; Foreign Minister Andrii Sybiha later said the dispute stemmed from differing interpretations of the confidentiality requirements at various stages of the transfer.

Sybiha’s explanation points to the more useful lesson. An informal diplomatic understanding is not inherently defective, but whatever understandings and consultation process existed were not enough to prevent the disclosure dispute. Seoul had substantial reasons for discretion, including possible risks to the soldiers and their relatives who remain in North Korea. Ukraine had strong motives for publicity: North Korean troops are participating in the ongoing Russia-Ukraine war, and more are expected to arrive on the frontlines. 

South Korea’s intelligence service has also told lawmakers that Ukraine originally requested secrecy, partly because the transfer of North Korean POWs could invite criticism that Ukraine had forgone a possible prisoner-exchange opportunity. If that account is correct, the incentives for secrecy and publicity shifted over time. Agreements that must survive shifting incentives need to be written down.

Of course, given the lack of clarity around confidentiality, Kyiv should have consulted with Seoul rather than proceeding with a public announcement. South Korea was justified in demanding an explanation and safeguards to prevent a recurrence. Ukraine later sent language that South Korean Foreign Minister Cho Hyun said contained an apology, but Seoul deemed it insufficient. Kyiv later declared the controversy closed. 

For now, the two governments are stuck defending incompatible accounts of the past. What they should be doing is figuring out how to handle the next case.

The deeper problem is that the issues passing through their bilateral channels have evolved faster than the practices for handling them. To give an idea of the robustness – or lack thereof – of bilateral mechanisms before Russia’s invasion, the eighth round of foreign ministry political consultations in 2019 came after a seven-year gap and focused largely on conventional bilateral diplomacy. 

As recently as September 16, a week before Zelenskyy’s speech, Ukrainian officials were discussing reviving those consultations. But the older platforms for discussion aren’t fit for purpose anymore. After North Korean troops entered Russia’s war, Zelenskyy and then-South Korean President Yoon Suk-yeol agreed in October 2024 to intensify intelligence and expertise exchanges. Their foreign ministers have discussed battlefield conditions, North Korean prisoners, and Russia-North Korea military cooperation. In 2019, they were talking about “trade, investment, science, technology, and agriculture” – far less sensitive topics.

That means the same questions are likely to recur in South Korea-Ukraine relations. Ukrainian forces encounter North Korean troops and weapons in combat; South Korea wants to know what those encounters reveal about tactics, missile performance, battlefield adaptation, and Russian assistance. Future cases could involve another prisoner, captured equipment, debriefing materials, sanctions intelligence, or evidence of Russian technology transfers. Each could raise the same basic questions: what information is jointly sensitive, who may disclose it, and what happens if the other government objects?

Ukraine’s foreign minister has called the two countries “natural allies,” but Seoul has not adopted Kyiv’s strategic position toward Russia and continues to withhold direct lethal assistance. Seoul has its own reasons to preserve diplomatic space with Moscow and Pyongyang. The two governments do not need identical interests, but they do need ground rules for handling the information they are already sharing. 

First, South Korea and Ukraine should define confidentiality in writing. For jointly handled information or information shared under agreed restrictions, the two governments should document what is protected, how long the restriction applies, and who may authorize disclosure. In the POW spat, Kyiv’s first response was to deny that any agreement existed; a written text would have clearly established the existence and scope of any commitment.

Second, an objection should trigger a defined escalation process. Advance notice was insufficient in the POW case. Kyiv warned that Zelenskyy would speak at the U.N. and might raise the case, and Seoul responded by objecting to public disclosure. But the speech went ahead, even though the disagreement remained unresolved. Future cases should require another round of consultation when either government objects to disclosure – first among the officials handling the issue and, if necessary, between senior political offices. That would not guarantee compromise, nor should it give either government an indefinite veto over the other’s public statements. It would move the disagreement to a point where compromise remains possible.

Third, South Korea and Ukraine need to give Russia-North Korea security cooperation a standing, quiet place within the bilateral relationship. If Seoul and Kyiv do revive their political consultations, those talks should include a regular security track to compare assessments of North Korean battlefield performance, weapons, Russian assistance, North Korean personnel returning from the war, and other lessons relevant to the Korean Peninsula. Their existing intelligence and expertise exchanges should feed into this track. 

The point is continuity: officials should not have to rebuild priorities, contacts, and disclosure boundaries every time a new incident forces the issue. The same track should host the written terms and escalation contacts, so officials who know one another can try to resolve an objection before it reaches the leaders.

These principles could help resolve the current standoff. Seoul wants Ukraine to acknowledge that confidentiality was part of the talks; Kyiv maintains that there was never a firm agreement. A possible compromise would acknowledge that confidentiality was discussed, that the two sides understood its scope differently, and that future sensitive cases will use written terms and a defined consultation process before any disclosure. The first two elements broadly align with Sybiha’s own formula, so the statement would ask Kyiv to concede less than it may seem. 

Ukraine could also express regret for any added risk to soldiers’ relatives. That would differ from the regret Kyiv’s Foreign Ministry has expressed so far, which focused on the dispute’s escalation into public criticism, and would give Seoul something closer to the acknowledgment it has sought. Such a statement would not require Seoul to abandon its account of the negotiations or Kyiv to admit a deliberate breach. Three European governments have reportedly offered to help ease tensions, suggesting that outside assistance may be available.

Even as Seoul reduces its diplomatic presence in Kyiv, it says humanitarian and reconstruction support for Ukraine will continue. Still, the expanding confrontation shows how difficult it can be to keep one grievance from overshadowing broader cooperation. Ground rules will not eliminate the larger differences between the two governments – Seoul’s interest in preserving room for dialogue with Pyongyang and Kyiv’s in exposing North Korea’s role in the war – and leaders can always ignore procedures. But a written agreement and clear procedures for handling disclosure will help head off similar cases before they erupt into public view.

Russia and North Korea have built a partnership suited to the war they are now fighting together. Seoul and Kyiv don’t need a formal alliance, but they do need better channels to handle the sensitive information that’s now a part of their partnership: the next prisoner, the next captured weapon, the next intelligence finding, and the next disagreement over who gets to tell the world.