South Korea’s ambassador to Kyiv returned to Seoul on Saturday, his recall the latest in a series of tit-for-tat actions that have severely strained bilateral ties.

The sudden deterioration in their relationship can be traced back to September 23, when Ukrainian President Volodymyr Zelenskyy told the United Nations General Assembly in New York that Ukraine had transferred two captured North Korean soldiers to South Korea.

The soldiers had been captured by Ukrainian forces in the Russian Kursk region in January 2025 as they fought alongside Russian troops.

The South Korean government immediately expressed its anger at Zelenskyy’s revelation, insisting that the two governments had reached an agreement to keep the transfer of the two men in mid-September a secret.

Kyiv hit back, by saying that no confidentiality agreement had been in place, to which South Korea accused Ukraine of effectively lying and demanded an official explanation and an apology.

Ukraine has attempted to smooth over what it has called a “diplomatic understanding,” but stopped short of the public apology that was expected in Seoul.

Then, reports emerged last week that a close adviser to Zelenskyy had said that more than 176,000 tons of diesel and other energy products were shipped to Russia from South Korean ports in July and August of this year, which would be a breach of international sanctions.

The office of president Lee Jae Myung in Seoul denied the accusation, and two days later recalled its ambassador to Kyiv.

There are several reasons why South Korea wanted to keep the POW transfer secret, Erwin Tan, a professor of international politics at Hankuk University, told DW. “The first was that revealing that the POWs had been repatriated to South Korea would result in Pyongyang retaliating against the families of the men for surrendering,” Tan said.

“Seoul also wanted to maintain a channel for communication with Pyongyang,” Tan said. “This is a major consideration for the left-leaning wing of Korean politics, which includes President Lee and has historically favored seeking rapprochement with the North.”Kim Sang-woo, a former politician with the left-leaning South Korean Congress for New Politics and now a member of the board of the Kim Dae-jung Peace Foundation, agrees that the South Korean government wanted to avoid “friction” with the North.

But Kim pointed out that it was always very likely that both Moscow and Pyongyang would find out about the transfer sooner or later and that Lee was being criticized in some quarters at home for appearing weak.

“There is criticism that Lee’s administration is effectively appeasing the North, that it has become too soft, and that is a very worrisome situation,” Kim said. Yet he admits to being surprised at how quickly the issue escalated.

“I think Lee was very angry that he was publicly being accused of lying about the agreement and it rapidly grew into a very messy confrontation,” he said.

While it is unclear why Zelenskyy used his high-profile UN speech to announce the repatriation of the two POWs, Kim believes it may have been a calculated move to win more support from Seoul. Kyiv could have carried out a prisoner swap with the Russians and won the freedom of some of its own men in return. But, Kim pointed out, Ukraine instead chose to accede to Seoul’s request in the hope that South Korea would respond with additional financial and possibly even military support. That move appears to have backfired. Professor Tan anticipates that the two governments will continue to “vent steam” over the issue.

“Given the high profile nature of the mutual accusations, both sides will probably engage in a mutual blame game for the immediate future, but I doubt that it will turn into a long-term case of mutual acrimony,” he said.

“I anticipate that after the furor has died down and the press is looking for the next new story, both sides will quietly resume contact on the basis of mutual pragmatism.”