South Korea’s President Lee Jae Myung was effusive as he welcomed home the crew of the container ship PanStar Acro from a voyage across the Arctic. Hailing the crew’s “courage and sense of responsibility” on “distant seas”, Lee pledged to “answer with unwavering action and open a new path for the Republic of Korea”.

European diplomats in Seoul were less enthused. Sailing the Northern Sea Route, which hugs the Russian Arctic coast, shaves 10 days off European journeys via the Suez Canal but requires extensive co-operation from Moscow.

The voyage, South Korea’s first, which returned this month, was emblematic of what European officials see as a diplomatic and commercial tilt by Seoul towards Moscow, even as the Kremlin deepens its partnership with North Korea and continues its war against Ukraine.

Those concerns were heightened by reports this month that more than 176,000 tonnes of fuel, mostly diesel, were shipped from South Korea to Russia in July and August, including aboard tankers subject to UK and EU sanctions.

Seoul’s relationship with Moscow has prompted some European diplomats to question whether South Korea — which they saw as a “like-minded” democracy, with shared economic and security interests — remains a reliable partner.

“[The South Koreans] aren’t really ‘like-minded’,” said one Seoul-based European diplomat who requested anonymity. “The attitude is that the [Ukraine] war won’t last for ever, and they want to get right back into business with Russia as soon as it’s over.”

European concerns over Seoul’s attitude to Russia predate Lee’s presidency. South Korea’s lax enforcement of its export controls on computer numerical control (CNC) machines, which can be used to produce munitions, has been a particular source of frustration.

Some observers say those concerns have grown under Lee, who took office in June 2025. Mason Richey, professor of international politics at Hankuk University of Foreign Studies in Seoul, said that South Korean-Russian relations had been “improving quietly” since last autumn.

In November 2025, the Institute for National Security Strategy, which is affiliated with Korea’s National Intelligence Service, held a closed-door conference with the Russian International Affairs Council, a Kremlin-backed think-tank aimed at finding opportunities for political dialogue and “prospects for expanding economic co-operation”, according to the RIAC website.

In June, INSS president Kim Seong-bae travelled to Moscow for a closed-door strategic dialogue with Russian counterparts, according to RIAC.

This month, Lee appointed Song Young-gil, a former leader of his Democratic Party, as special adviser for peace diplomacy. Song, who also served as a presidential envoy to Russia, has long advocated for closer ties with Moscow, and was awarded Russia’s Order of Friendship by President Vladimir Putin at the Kremlin in 2013.

Meanwhile, Seoul’s relationship with Kyiv has deteriorated following a dispute over the disclosure last month that two North Korean prisoners of war had been transferred from Ukraine to South Korea.

Lee has accused Kyiv of violating a secrecy agreement over transfer and demanded an apology. Seoul this month recalled its ambassador to Kyiv, its first such move since 2008, while Korea’s foreign ministry said it would withdraw additional embassy staff. Ukrainian officials have disputed the Korean account, calling it a “diplomatic misunderstanding”.

European leverage is also limited by the increasing importance of South Korea’s defence industry, which has helped replenish European stockpiles drawn down to arm Ukraine. Poland alone has ordered more than $18bn of Korean tanks, howitzers, fighter jets and rocket launchers since 2022.

European governments “still need weapons — precisely because of [the Ukraine] situation,” Richey said. South Korea is “not easily replaced”.