South Korea's fuel shipments to Russia via sanctioned tankers undermine Ukraine support

South Korea's ports have become a crucial supply line for Russian fuel, according to shipping records and vessel-tracking data analyzed by The Guardian. Between July and August, more than 176,000 tonnes of diesel and other fuel products were loaded onto seven tankers at South Korean ports, which then made fourteen separate voyages to Russia's far eastern terminals. Three of those vessels were operating under active sanctions imposed by the UK and EU—a detail that exposes a widening gap between Seoul's public commitments to Ukraine and what its ports are actually enabling.

The mechanics of these shipments reveal how sanctions can be circumvented through deliberate routing and paperwork. The Layla, a sanctioned tanker, departed from the southeastern port of Ulsan twice in July and August, carrying 57,000 tonnes of diesel to Vladivostok. On its second voyage, the ship's manifest listed Niigata, Japan, as the destination—a common tactic to obscure the true endpoint. The Astoria, a Russian-flagged vessel also under Australian sanctions, loaded nearly 11,000 tonnes at Ulsan on August 1st and similarly declared Japan as its destination before sailing to Vladivostok. Most striking was the Chongchon, which never even docked. Instead, it received approximately 26,000 tonnes of fuel through a ship-to-ship transfer from another tanker anchored off the southern port of Yeosu in early August, a method that leaves no paper trail at port terminals and obscures the cargo's origin entirely.

The timing and scale of these shipments matter because Russia's refining capacity has been severely degraded by Ukrainian drone strikes. The International Energy Agency reported that Russian refinery throughput fell to its lowest level in more than two decades in June, and diesel production has dropped nearly 30 percent compared to the previous year. Ukraine's military intelligence agency has stated that Moscow has been forced to import fuel products to sustain its war effort. In August alone, Russia imported 368,000 tonnes of oil products by sea—more than seven times the previous month and the highest monthly total since the full-scale invasion began. South Korea accounted for 112,000 tonnes of that total, or 31 percent, making it the second-largest supplier after India.

The buyers identified through maritime analytics data included Rosneft, Russia's state-controlled oil company, which is sanctioned by the UK, US, EU, and Australia, and NNK, a Russian oil group whose owner and subsidiary are under UK sanctions. Yet these shipments do not appear to violate South Korean law. Seoul's sanctions regime relies primarily on export controls for industrial machinery, electronics, and vehicles—not fuel. The country has sent Ukraine humanitarian aid and non-lethal military supplies including helmets, body armor, and demining vehicles, and pledged $2.3 billion in support in 2023, mostly in the form of loans. But South Korea has consistently refused to send weapons directly to Ukraine, adhering to a longstanding policy against supplying lethal arms to countries engaged in active conflict.

This balancing act reflects Seoul's broader strategic calculation. South Korea has long sought to improve relations with Russia, and Moscow has signaled interest in restoring trade ties. In March, as regional tensions escalated, South Korea imported Russian naphtha under a US sanctions waiver and capped exports of certain fuels. Just days before the fuel shipments began surging in July, South Korea's president, Lee Jae Myung, pledged $100 million for Ukraine's reconstruction at a NATO summit in Turkey. A 2025 trade association survey found that nearly 80 percent of South Korean firms that had halted exports to Russia since the war began were willing to resume business.

When contacted by The Guardian, South Korea's foreign ministry did not address the specific shipments or the sanctioned tankers. Instead, it issued a statement describing the country as "a responsible member of the international community" and noting that it had expanded export controls to cover 1,402 non-strategic items with potential military applications. The UK Foreign Office similarly declined to answer questions about whether the UK-sanctioned tankers using South Korean ports had been raised with Seoul, though it reiterated its commitment to monitoring sanctions and pressuring Russia economically.

Isaac Levi, an analyst at the Centre for Research on Energy and Clean Air, a Finnish research organization, called the situation "shocking," saying it "undermines the sanctions regime and South Korea's support for Ukraine." The shipments risk positioning Seoul as a weak link in Western efforts to isolate Russia economically, particularly as relations with Kyiv have already grown strained over the recent transfer of two North Korean prisoners of war to South Korea—a move Seoul says was meant to remain confidential. The question now is whether Western allies will pressure South Korea to tighten controls beyond what its current laws require, or whether Seoul will continue to navigate the space between its stated solidarity with Ukraine and its strategic interest in restoring ties with Moscow.