South Korea’s presidential office demanded an official explanation and apology from Ukraine on Sunday, accusing Kyiv of unilaterally disclosing the transfer of two North Korean soldiers to South Korea. It also accused Ukraine of falsely denying a non-disclosure agreement existed.

Senior presidential secretary Seong Ghi-hong said the office expressed strong regret over the disclosure and the denial. Seoul is reviewing additional measures if necessary.

Seoul says Ukraine had repeatedly requested secrecy, warning that disclosure could trigger domestic criticism that Kyiv gave up a chance to exchange the soldiers for Ukrainian prisoners. Zelenskiy revealed the transfer in his UN General Assembly address without sufficient prior consultation, Seoul said.

Ukraine’s embassy in Seoul did not immediately respond to Reuters’ request for comment. No Ukrainian rebuttal was found at the time of reporting.

The dispute centers on two North Korean soldiers captured while fighting for Russia, whom Zelenskiy said last week had been transferred to South Korea.