The Kyiv-Seoul relationship is souring, and so far the U.S. isn’t stepping in

Addressing the United Nations General Assembly last month, Ukrainian President Volodymyr Zelensky revealed that his government had sent two North Korean prisoners of war to South Korea, the first such transfer since Pyongyang dispatched troops two years ago to support Russia’s invasion.

The presence of North Korean soldiers in Russia was first revealed by South Korean intelligence. It was emblematic of the broader global dangers of the conflict − many in South Korea fear Pyongyang is using the war in Ukraine to gain battlefield experience that may one day prove useful against its neighbour − and the good relationship between Kyiv and Seoul, a major U.S. ally.

But Seoul reacted with fury to Mr. Zelensky’s comments on Sept. 23, claiming there had been a “clear understanding” that the transfer would be kept secret. South Korean President Lee Jae Myung accused Kyiv of turning the incident “into a spectacle for the sake of claiming credit,” endangering both the men involved (whose families in North Korea could face backlash) and South Korea’s own security, given the unpredictability of its volatile neighbour.

While Kyiv attempted to smooth over what it called a “diplomatic misunderstanding,” Ukrainian officials have continued to deny that they breached any formal agreement, further angering Seoul, which viewed this as tantamount to calling Mr. Lee a liar.

For many observers, the sudden deterioration in ties has come as a shock, particularly as South Korea had been an important ally to Ukraine in Asia, where many countries continue to trade with Russia.

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The situation escalated further last week, when The Guardian reported that more than 176,000 tonnes of diesel and other fuel were shipped from South Korea to Russia’s far east in July and August, potentially in breach of international sanctions. Ukraine had been attacking Russian oil refineries, so the shipments helped Moscow offset what could have been a crippling fuel shortage, according to Ukraine’s Presidential Commissioner for Sanctions Policy, Vladyslav Vlasiuk.

South Korea has denied the report and Mr. Vlasiuk’s accusations, and Seoul responded by withdrawing its ambassador from Kyiv, even as both sides have said they wish to find a way forward.

According to several reports, Mr. Zelensky’s purpose in revealing the prisoner transfer may have been to bolster support in South Korea for providing weapons to Ukraine, which Mr. Lee’s government has so far refused to do, though he committed a further US$100-million in non-lethal aid in July.

If so, Kyiv profoundly misjudged the mood in Seoul, where Mr. Lee’s government has been seeking to restart the stalled Korean peace process after U.S. President Donald Trump floated a potential meeting with North Korean leader Kim Jong Un.

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Joseph Webster, a senior fellow at the Atlantic Council, said the backdrop to the current spat is Seoul’s and Kyiv’s “increasingly complicated security relationship with the United States.”

“Normally, the U.S. would firmly support the security of both partners, especially its ally, South Korea, and work behind the scenes diplomatically to smooth out the dispute. Instead, the U.S. is aloof, or even adversarial,” he said. “In the absence of firmer security ties with D.C., both Ukraine and South Korea are trying to make their own way in a dangerous world, even if that means playing hardball with other democracies.”

South Korea is highly vulnerable to disruptions in the oil market, which has been thrown into chaos by Ukraine war and Mr. Trump’s subsequent attacks on Iran. With the U.S. lifting sanctions on Russian diesel, many in Kyiv fear Seoul will follow Mr. Trump’s lead and resume trade with Moscow, alleviating some of the pressure on its own economy.

“Seoul is very unlikely to fundamentally transform its relationship with Russia and Ukraine, but its diplomatic irritation with Kyiv and oil price angst are real,” Mr. Webster said. “Getting out of the situation will be difficult, not least because the U.S. is not present, and few other powers enjoy credibility with both Kyiv and Seoul. Canadian diplomacy may prove vital during this test of the middle-power strategy.”