International Law in Action: Navigating the Seas to Intercept Sanctioned Russian Oil

The Law of the Sea is being actively employed in the pursuit of sanctioned Russian oil, as evidenced by a recent European Union inspection. An Italian military helicopter observed the oil tanker Toa Payoh, with the Italian Navy ship Thaon di Revel nearby, during an inspection in international waters west of the Italian island of Pantelleria on August 2, 2026. The Italian Defence Ministry confirmed that the EU-sanctioned tanker had declared a Cameroon flag and was identified as part of Russia’s so-called 'shadow fleet'.

Following the reversal of certain sanctions policies on Russian oil by US President Donald Trump, Ukraine’s Western allies have intensified their use of international law. Experts have informed Al Jazeera that countries sanctioning Russian oil have, for the first time this year, exercised their rights to board and inspect vessels under the Law of the Sea. Michelle Bockmann, an analyst at maritime intelligence company Windward, stated, “The whole idea now is to disrupt, deter and make it more expensive and costly for Russia to logistically get their oil to market on these ships, and that’s definitely happening.”

Some Russian officials anticipate further actions. Nikolai Patrushev, chairman of the Russian Maritime Board, told officials during a visit to China on October 12, “Western countries are trying to organise the interception of our vessels. London and Brussels are drawing up plans to blockade the Baltic Sea and the straits leading into it. Other key shipping routes are also under threat.”

Western sanctions extend beyond prohibiting the purchase of Russian oil within sanctioning territories. They also prevent Western-insured tankers from selling Russian oil to third parties, except at below-market prices, significantly reducing Russia's profit margins. Since the imposition of sanctions in 2022, Russia has been exporting approximately half of its crude oil via a “shadow fleet” of tankers not owned or insured by Western institutions, often failing to meet environmental and safety standards. The right to enforce these standards allows the United States, United Kingdom, and European Union to conduct compliance inspections under Article 110 of the United Nations Convention on the Law of the Sea (UNCLOS), which grants coastal states the authority to inspect vessels.

This has diminished Russia’s capacity to circumvent oil sanctions, a challenge that has persisted for 45 months since the EU, US, and other Group of Seven (G7) states first imposed them. Bockmann noted, “A lot of these ships were using fraudulent registries, and they were stateless.” She explained that under UNCLOS, “Instead of just hailing them, ‘Hey, what’s your flag? What’s your insurance?’ and then letting them merrily go on their way under the right of innocent passage … they now had a legal basis to board them.”

Shadow tankers have engaged in various illicit activities, making them susceptible to suspicion and boarding. These include transferring Russian oil between vessels on the high seas to obscure its origin, disabling trackers to evade monitoring, falsifying their positions, evading insurance obligations, and flying false flags. The US initiated the use of Article 110 against such practices late last year by boarding vessels evading US Department of the Treasury sanctions against Venezuelan oil exports in Operation Southern Spear. With assistance from the UK, US Marines seized the Russian-owned Bella I in the North Atlantic last January, a vessel sanctioned for carrying Iranian, Venezuelan, and Russian oil. The UK and France have since boarded several other vessels under UNCLOS regulations.

While these inspections are infrequent compared to the vast number of shadow tankers operating, they have exerted pressure on this fleet, according to experts. Kristina Siig, a professor of economic law at Aalborg University in Denmark, commented, “Article 110 had just been sitting there, not really getting any traction. The tool has always been there, but it just never got pulled out of the drawer.”

This increased adherence to international law has had ripple effects throughout the shipping industry. George Xiradakis, a maritime consultant, stated, “Due diligence has become the biggest headache in ship management.” He advised Al Jazeera that ship charterers and buyers “have to check thoroughly that a ship is in compliance with international standards,” noting that the time required for these checks has increased significantly compared to 2025.

Sanctioning nations have pursued the shadow fleet rigorously. After being excluded from Western fleets, Russia turned to flags of convenience. However, the EU, UK, and US successfully persuaded those registries to de-register shadow vessels. Bockmann reported, “St Kitts and Nevis were the very first ones in early 2024… Palau, Gabon, Gambia, Cook Islands, San Marino, Barbados, Comoros, Guinea-Bissau, Sao Tome – they’ve all stopped.” Russia responded this year by registering many of these tankers under its own flag, with TankerTrackers.com listing 340 dark or shadow tankers as Russian-flagged. Sanctioning states have countered by utilizing UNCLOS.

Ukrainian President Volodymyr Zelenskyy aims to halt all of Russia’s fossil fuel export revenue and has warned that any rapprochement with Moscow by Trump could prolong the Russia-Ukraine war. Kyiv has targeted at least 26 of Russia’s 30 refineries this year, impacting the global market. The Centre for Research on Energy and Clean Air (CREA) calculated that Russia experienced an initial windfall of 31 billion euros ($35 billion) this year, partly due to increased oil and gas prices caused by the crisis in the Strait of Hormuz. This temporarily offset a trend of declining Russian oil and gas revenues since the Ukraine war began in 2022, with month-on-month revenues rising by 52 percent in March. However, Russia’s revenues from crude oil, refined products, and gas all decreased by eight percent in August, following a 12 percent drop in July and a one percent drop in June.

The official justification for these inspections is safety, and under UNCLOS, “we have a right, we actually have a joint obligation, to try to help each other to police that,” said Siig. However, she clarified that the underlying agenda of these inspections—to halt Russia’s war of aggression in Ukraine by disrupting its oil trade—is not directly enforceable under UNCLOS. “We are not allowed to tell certain states that they can’t export goods. The only entity that can do that is the UN. To enforce sanctions, you have to have state jurisdiction.”

This interplay of national and international law makes Denmark and Sweden crucial, as they control the narrow Baltic Sea chokepoints through which shipping must pass to reach the North Sea and the Atlantic. Tankers carrying crude oil and petroleum products from the Ust-Luga and Primorsk refineries in the Leningrad region must transit through Danish and Swedish territorial waters, where national laws are fully applicable, to access global markets. The Danish Maritime Authority reported 292 Russian shadow tanker transits through the Baltic in 2025 and has progressively strengthened its inspection regime. In February 2025, Danish authorities began compliance inspections on tankers anchored off Skagen, detaining the Vietnamese-flagged shadow tanker Vigo in April due to lax fire safety standards. In October, Denmark expanded its inspections to include ballast systems, fuel quality, emissions, waste management, and certificate verification.

“The Danish approach has been to throw the book at [Russia],” Siig observed, noting that Danish authorities now require an oil insurance certificate, a sail plan through the Danish Straits, and safety documents in addition to an insurance certificate. Russia has reacted with anger to the perceived pressure, particularly the risk of being confined to the Baltic Sea. On September 14, a Russian frigate fired two flares at a Danish helicopter conducting an inspection in international waters south of Gedser, in the Danish Straits. A recent report from the Danish Defence Intelligence Service stated, “Russian forces are increasingly acting aggressively towards NATO military units in the Baltic Sea region.” The report further noted, “Russia is under more pressure than it has been at any other point during the war against Ukraine. Ukraine’s sustained long-range attacks are causing still more extensive damage deep inside Russia… The Russian economy is on the brink of a major crisis, driven by military expenditures, international sanctions and Ukrainian strikes.”

Siig indicated that Denmark is proceeding cautiously as it applies these international law provisions for the first time. While Danish authorities may now request an oil insurance certificate, safety documents, a sail plan through the Danish Straits, and an insurance certificate, closing off the Strait is not under consideration. “I have seen no public evidence that such a measure is being considered. Under the ordinary Law of the Sea regime, the Danish Straits are international straits subject to transit passage, and the Kingdom of Denmark has a strong interest in preserving that rules-based system,” Siig stated. “Russia has lost the Baltic,” she concluded. “Everybody seemed to be getting along just fine. Then Ukraine happened, and suddenly they got boxed in, geopolitically.” Ukraine has urged its allies to enforce sanctions more rigorously, a move Siig suggested “might stop the Ukrainian war, and it might start a new one.”