The shadow fleet is undermining the maritime order more brazenly than ever
Bottom lines up front
- In 2026, the Baltic Sea countries, France, India, and others have inspected and detained more shadow-fleet vessels than in prior years.
- In response, Russian military vessels have begun escorting shadow vessels through the English Channel and Baltic Sea.
- Some Iranian shadow vessels have been able to sail despite the war in Iran and Iran’s blockade of the Strait of Hormuz. A not insignificant number have also managed to evade the United States’ blockade of Iranian ports.
Since the end of 2022, the shadow fleet—a large and growing group of ships that sail outside the official shipping system—has been in the news because of its role transporting sanctioned Russian oil. In March 2026, Iranian shadow vessels began attracting attention as well, as they have been able to keep sailing despite one and then two blockades amid the war in Iran.
Although there is no official definition of shadow vessels—also known as the dark fleet, the ghost fleet, or the parallel fleet—they are disproportionately old and typically feature these characteristics:
- Transport sanctioned cargo
- Have opaque ownership
- Lack insurance of the International Group of P&I Clubs (protection and indemnity associations)
- Are often aging, in poor condition, or both
- Frequently conceal their movements
In some ways, it is not surprising that the shadow fleet has emerged in recent decades: It has arisen in parallel with the rules-based international system, which came into being in the decades after World War II, with the early participation of the shipping sector. When countries violated the rules-based international order and, as a result, were put under economic sanctions by other nations, they resorted to the shadow fleet for imports and exports. South Africa used shadow vessels during the apartheid era. Countries such as Iran, Venezuela, and North Korea have relied on shadow vessels for years, even decades.
These are, however, relatively small economies. When Russia turned to the shadow fleet following Western governments’ introduction of a $60 per barrel price cap on Russian oil in December 2022, the shadow fleet grew dramatically. Whereas it had previously encompassed an estimated two hundred ships, in November 2023, more than 1,600 oil and product tankers had operated in the “opaque market” since January 2021.1Elisabeth Braw, “The Threats Posed by the Global Shadow Fleet—and How to Stop It,” Atlantic Council, December 6, 2024, https://www.atlanticcouncil.org/in-depth-research-reports/report/the-threats-posed-by-the-global-shadow-fleet-and-how-to-stop-it/
Since then, the shadow fleet has continued to operate. In August 2025, broker BRS estimated that there were 1,140 shadow oil tankers, more than 18 percent of the global oil tanker fleet.2Sam Chambers, “Shadow Tanker Fleet Still Growing by 30 Ships a Month Despite Increased Sanctions,” Splash247, Asia Shipping Media, August 5, 2025, https://splash247.com/shadow-tanker-fleet-still-growing-by-30-ships-a-month-despite-increased-sanctions/ Other ship categories have also seen the number of shadow vessels grow.
The large shadow fleet has come to pose a significant problem for coastal states and legally operating vessels. These risks include collisions and other accidents; spills of oil and other hazardous substances; and the threats to the maritime order itself that arise when a significant minority of ships do not uphold rules. In the Baltic Sea, the route most commonly used by the shadow fleet, these risks have raised especially serious concerns.
Shadow vessels have also damaged undersea cables, sometimes under mysterious circumstances. On Christmas Day of 2024, the Cook Islands-flagged shadow tanker Eagle S struck four data cables and one interconnector cable in the Gulf of Finland, the Baltic Sea’s eastern end.3“Maps Reveal the Path of the Eagle S on Christmas Day,” YLE News, Updated December 27, 2024, https://yle.fi/a/74-20133606 The incident caused considerable losses in connectivity and power provision, as well as financial losses for the operators; in the case of EstLink 2, the interconnector, its operators estimated the cost of repairs at about €60 million ($69 million).4Winston Qui, “Repair of EstLink 2 Electricity Subsea Cable Costs up to €60 million,” Submarine Networks, May 28, 2025, https://www.submarinenetworks.com/en/nv/insights/repair-of-estlink-2-electricity-subsea-cable-costs-up-to-%E2%82%AC60-million
In addition, the shadow vessels continue to pose a severe environmental risk. In a simulation of an accident in February 2026, a research center in Geesthacht, Germany, calculated how a hypothetical spill of 48,000 tons of Urals crude oil would spread over thirty days.5“How a Shadow Fleet Accident Would Affect the Baltic Sea,” Hansa.News, February 18, 2026, https://hansa.news/how-a-shadow-fleet-accident-would-affect-the-baltic-sea/ The simulation projected devastating effects, even with such a relatively limited spill. (The tankers that carry sanctioned oil from Russia’s Baltic ports—key ports of departure for Russian oil—through the Baltic Sea are typically of the Suez-max class, with capacity of 160,000 deadweight tons.6“A Guide to Bulk Vessel Sizes,” Clarksons, accessed April 3, 2026, https://www.clarksons.com/home/glossary/v/a-guide-to-bulk-vessel-sizes/)
In recent months, Danish pilots—the Western Europeans with the closest proximity to shadow vessels—have also reported noticing a deterioration in the quality of the seafarers on board.7Elisabeth Braw, The Undersea War (John Murray/Basic Books), forthcoming. This is hardly surprising, as seafarers who have a choice to board a legitimately sailing vessel would clearly do so, not least for their own safety.
Measures to tackle the shadow fleet
As soon as it became apparent that Russia was turning to the shadow fleet for its exports of sanctioned oil, Western governments tried to stem the traffic. The first, and primary, way they have done so in the months and years since is through sanctions of individual vessels. As of early 2026, the European Union has listed nearly six hundred shadow vessels by adding them to the list “of those subject to a port access ban and ban on provision of a broad range of services related to maritime transport.”8“Russia’s War of Aggression against Ukraine: Council Sanctions 41 Vessels of the Russian Shadow Fleet,” Press Release, Council of the EU, December 18, 2025,
https://www.consilium.europa.eu/en/press/press-releases/2025/12/18/russia-s-war-of-aggression-against-ukraine-council-sanctions-41-vessels-of-the-russian-shadow-fleet More than four hundred ships have been sanctioned by the EU, the United Kingdom, the United States, and Canada.9“Red ALERT: Shadow Fleet Sanctions Evasion and Avoidance Network,” United Kingdom’s National Crime Agency, July 2025, https://www.nationalcrimeagency.gov.uk/who-we-are/publications/753-red-alert-shadow-fleet-sanctions-evasion-and-avoidance-network/file
In December 2024, twelve European countries—Britain, Germany, Poland, the Netherlands, five Nordic nations, and the three Baltic states announced that they would begin checking suspected shadow vessels’ insurance certificates. (Under international maritime rules, vessels are required to have P&I insurance, and there was evidence that shadow vessels were sailing without proper P&I insurance as there were very few alternatives to the coverage offered by the International Group of P&I clubs, which are based in Western countries and thus subject to Western laws.) Six of the countries—Britain, Denmark, Sweden, Poland, Finland, and Estonia—would begin carrying out inspections in the English Channel, the Danish straits, the Gulf of Finland, and the Kattegat between Sweden and Denmark. “If the ships do not cooperate, next steps will be taken: they will be put on a list for prohibition, or they will be boarded in certain areas,” Estonian Prime Minister Kristen Michal said at the time.10Andrius Sytas, “Russian ‘Shadow Fleet’ to Be Boarded or Sanctioned if It Refuses to Prove Insurance,” Reuters, December 17, 2024, https://www.reuters.com/world/europe/russian-shadow-fleet-be-boarded-or-sanctioned-if-it-refuses-prove-insurance-2024-12-17/ By April 2025, Estonia had requested proof of insurance from more than five hundred vessels; by January 2026, the UK government had done so from more than six hundred suspected shadow vessels.11Minister for Foreign Affairs of the Republic of Estonia Margus Tsahkna, “We Will Continue to Deter Russian Shadow Fleet Vessels Sailing under Flags of Convenience,” Press Release, Republic of Estonia Ministry of Foreign Affairs, April 28, 2025, https://vm.ee/en/news/foreign-minister-tsahkna-we-will-continue-deter-russian-shadow-fleet-vessels-sailing-under; Thomas Copeland, “Tracking shows eight sanctioned Russian tankers currently in the English Channel,” BBC, January 30, 2026, https://www.bbc.co.uk/news/live/cy8yw4y7dw9t
The Baltic Sea states, as well as the UK, have also increased patrolling. In the Baltic Sea, the patrolling is also conducted by Commander Task Force Baltic, a German-led initiative comprising sailors, naval aviators, marines, ships, and aircraft from thirteen NATO member states, to which the NATO-initiated Baltic Sentry, a “multi-domain activity,” has been added.12“Commander Task Force Baltic Established,” German Navy, October 21, 2024, https://www.bundeswehr.de/en/organization/navy/news/commander-task-force-baltic-established-5850832; and “Baltic Sentry,” Supreme Headquarters Allied Powers Europe, accessed March 26, 2026, https://shape.nato.int/operations/operations-and-missions/baltic-sentry
In December 2024, Finland broke new ground by boarding the Eagle S. The ship, which had just struck five undersea cables in the Gulf of Finland, was navigating in Finland’s exclusive economic zone (EEZ) and was approaching other fiber-optic cables and the EstLink 1 interconnector, which runs between Estonia and Finland. The Finnish Border Guard instructed the ship to enter Finnish territorial waters, where Border Guard and police officers boarded her.13Merja Niilola, “Tidigare gränsbevakningsutbildare: Myndigheterna tog kontroll över tankern på ett för Finland unikt sätt,” YLE, December 27, 2024, https://yle.fi/a/7-10069773; The ship was later escorted out of Finnish waters; in a criminal trial against the captain and the two chief mates the following year, a Finnish court ruled it had no jurisdiction in the matter.
Some flag-of-extreme-convenience nations have removed shadow vessels from their registries. For example, the government of Eswatini appears to have discovered that a private outfit was running a fraudulent ship registry in the country’s name; the government subsequently began deflagging ships registered by the outfit.14Richard Meade, “How Eswatini Created a Shipping Register by Accident,” Lloyd’s List, September 4, 2024, https://www.lloydslist.com/LL1148912/Eswatini-shipping-registry-flagged-as-false-operation-by-IMO Although plenty of flags of extreme convenience (the author’s term) are still willing to flag shadow vessels, being deflagged is an inconvenience for shadow vessels and their owners.
In April 2025, Estonian authorities detained the Kiwala, a shadow vessel that claimed to be flagged in Djibouti but was, in fact, sailing without flag registration.15Agence France-Presse, “Estonia Says Russian ‘Shadow Fleet’ Tanker Can’t Sail Without Resolving 40 Deficiencies,” via Moscow Times, April 13, 2025, https://www.themoscowtimes.com/2025/04/13/russian-shadow-fleet-tanker-detained-in-estonia-has-40-deficiencies-a88711 (The detention occurred after Estonian authorities had instructed the ship, which had been navigating in Estonia’s EEZ, to enter Estonian territorial waters.16Republic of Estonia, “Estonia Is Inspecting the Sanctioned Vessel Kiwala,” Transport Administration, April 11, 2025, https://www.transpordiamet.ee/en/news/estonia-inspecting-sanctioned-vessel-kiwala) An inspection showed that the Kiwala had numerous deficiencies. After most of them had been rectified and Djibouti had agreed to flag the ship for a few days, the Kiwala departed. The incident marked the first time a shadow vessel has brazenly sailed without flag registration.
Escalation in shadow fleet behavior
The behavior by the Kiwala and her owner demonstrated an increased willingness among shadow fleet participants to violate rules including cardinal ones such as flag registration, apparently because they believe that they will not be punished for doing so. Several weeks after Estonia’s detention of the Kiwala, Estonian authorities tried to detain another known shadow vessel, the Jaguar, in the country’s EEZ. This time, however, the ship did not obey the Estonian instructions to move into Estonian territorial waters. Instead, a Russian fighter jet responded by breaching Estonian airspace.17“Russian Fighter Jet Breaches Estonia’s Airspace,” ERR News (English-language portal of Estonian Public Broadcasting), updated May 16, 2025, https://news.err.ee/1609694252/russian-fighter-jet-breaches-estonia-s-airspace; and Richard Meade, “Dark Fleet Politics Escalate as Russia Scrambles Jet to Protect ‘Nationless’ Tanker,” Lloyd’s List, May 15, 2025, https://www.lloydslist.com/LL1153484/Dark-fleet-politics-escalate-as-Russia-scrambles-jet-to-protect-nationless-tanker
Soon after the Kiwala and Jaguar incidents, Finnish authorities warned that the Russian Navy had begun escorting shadow vessels through the Gulf of Finland.18Richard Meade, “Russian Naval Escorts Raise Stakes in Baltic Security Stand-off,” Lloyd’s List, May 27, 2025, https://www.lloydslist.com/LL1153663/Russian-naval-escorts-raise-stakes-in-Baltic-security-stand-off Such escorts appear to have been formalized in January 2026, when the Russian government’s maritime board decided to take measures that would, from the Russian perspective, protect merchant ships linked to Russia. “Issues related to ensuring the safety of navigation on strategic maritime routes are considered. Particular attention is paid to problems associated with violations of international maritime law by unfriendly states,” the Maritime Board said in a statement announcing the measure.19Atle Staalesen, “Russia Hints It Will Deploy Navy to Protect ‘Shadow Fleet,’” Barents Observer, January 28, 2026, https://www.thebarentsobserver.com/news/russia-hints-it-will-deploy-navy-to-protect-shadow-fleet/444331
The Russian escorts mark a new twist on maritime order. Traditionally, navies have occasionally escorted merchant vessels in waters plagued by pirates or other forms of violence. That occurred, for example, during the 1980s “Tanker War” between Iran and Iraq, when the United States escorted US-flagged vessels from the Persian Gulf through the Strait of Hormuz. Naval escorts of rule-breaking vessels through the waters of coastal states seeking to uphold maritime rules are a highly concerning development.
At the time of writing, the Strait of Hormuz dominates global news for another reason having to do with the maritime order. When the United States and Israel launched a war against it on February 28, 2026, Iran responded by threatening global shipping in the crucial and narrow strait; some merchant vessels were even hit by missiles. This rendered the strait de facto blocked and caused prices of oil and other crucial exports from the Persian Gulf to surge.
The de facto closure remained even after a ceasefire appeared to have been agreed, as transiting the strait remained subject to Iranian permission and, reportedly, the payment of substantial tolls. The ships successfully leaving the Persian Gulf included numerous shadow vessels transporting Iranian oil to international destinations. Like other shadow vessels, shadow vessels transporting Iranian cargo typically have flags of extreme convenience (the author’s term) such as Tanzania and Gabon.
On April 13, the United States imposed a blockade of its own, blocking ships navigating to and from Iranian ports. According to the US Central Command, during the first 48 hours the blockade, involving more than ten thousand US servicemembers, more than twelve ships and more than one hundred aircraft, successfully blockaded all ship traffic to and from Iranian ports. When BBC Verify, the BBC’s verification unit, checked this assertion using open-source intelligence, it could not be confirmed.20“Is the US blockade of Iran working?” BBC News, April 15, 2026, https://www.bbc.com/news/videos/cx2449xklnko Lloyd’s List reported on April 20 that several shadow vessels had evaded the blockade since it was imposed.21“At least 26 Iranian shadow fleet vessels bypass US blockade,” Lloyds List, April 20, 2026, https://www.lloydslist.com/LL1156966/At-least-26-Iranian-shadow-fleet-vessels-bypass-US-blockade
The number of shadow vessels sailing without valid flag registration has, in turn, grown rapidly since the first cases were observed in early 2025. The shipping-industry publication Lloyd’s List reports that the number of false-flagged ships in the Baltic Sea quadrupled during the second half of 2025, and in February 2026 the investigative news outlet Follow the Money reported that more than five hundred vessels were sailing without valid flag registration.22Follow the Money (FTM), “Hundreds of Shadow Fleet Ships Sail under False Flag,” FTM, February 12, 2026, https://www.ftm.eu/articles/hundreds-of-shadow-fleet-ships-sail-under-false-flag; and Bridget Diakun and Joshua Minchin, “False Flag Baltic Transits Almost Quadruple throughout 2025,” Lloyd’s List, February 6, 2026, https://www.lloydslist.com/LL1156288/False-flag-Baltic-transits-almost-quadruple-throughout-2025
Irregular passengers
In 2025, Danish pilots on shadow vessels crossing the Danish straits began seeing individuals on board who were not listed in crew documentation. “We’re seeing uniformed personnel carrying the camouflage uniform of the Russian Navy. When I’m on these ships, I do what I can to see the crew list. I want to see what I’m dealing with,” Bjarne Skinnerup, a Danish pilot, told this author in September 2025. But, he said, the uniformed officers were not on the crew lists. He suspected unofficial passengers might be mapping Danish infrastructure.23Elisabeth Braw, “Russia’s Shadow Fleet Is Doing More Than Sanctions-Busting,” Foreign Policy, October 2, 2025, https://foreignpolicy.com/2025/10/02/russia-shadow-fleet-pushpa-drones/ Since then, the Swedish Navy has said that it, too, has seen unlisted personnel on shadow vessels in the Baltic Sea.24“Marinen: Ryssland skyddar skuggflottan med militär operation,” SVT, December 15, 2025, https://www.svt.se/nyheter/inrikes/marinen-ryssland-skyddar-skuggflottan-med-militar-operation
It is not known what duties these passengers have. The very fact that they are on board without their names appearing in any documentation is, however, a violation of maritime rules and illustrates shadow vessels’ increasing brazenness.
Further measures to tackle the shadow fleet
On New Year’s Eve 2025, the Finnish Border Guard detained the cargo ship Fitburg—suspected of striking cables in the Gulf of Finland—after instructing the ship, sailing under the flag of Saint Vincent and the Grenadines, to enter Finnish territorial waters.25“Finnish Customs: The Cargo of the Vessel Fitburg Consisted of Sanctioned Steel Products,” Customs Press Release, January 1, 2026, https://tulli.fi/en/-/finnish-customs-the-cargo-of-the-vessel-fitburg-consisted-of-sanctioned-steel-products At the end of January 2026, French authorities detained the shadow tanker Grinch—which was sailing without a valid flag registration—between Spain and Morocco.26Raghib Raza, “Captain Detained After Tanker ‘Grinch’ Seized by French Authorities,” Marine Traffic, January 26, 2026, https://www.marinetraffic.com/it/maritime-news/16/general/2026/12648/captain-detained-after-tanker-grinch-seized-by-french-author A few weeks earlier, French authorities had detained the former Kiwala, the ship Estonian authorities had detained in May 2025. She had been renamed Boracay and purported to be flagged by Benin, but refused to provide evidence of her flag registration when instructed to do so by the authorities;27ERR News, “France Detains Shadow Fleet Vessel Previously Stopped by Estonian Authorities,” January 10, 2025, https://news.err.ee/1609816878/france-detains-shadow-fleet-vessel-previously-stopped-by-estonian-authorities in March 2026, the ship’s captain, a Chinese national, was convicted in absentia of failing to obey the authorities’ instructions.28Marion Solletty, “France Sentences Tanker Captain as EU Countries Crack Down on Russian Shadow Fleet,” Politico, March 30, 2026, https://www.politico.eu/article/china-captain-shadow-fleet-vessel-sentenced-france-amid-shadow-fleet-crackdown/
In the early months of 2026, similar detentions continued. In February, India boarded three Iranian shadow vessels some one hundred nautical miles off Mumbai in the Arabian Sea.29Will Xavier, “Indian Coast Guard Detains Suspected ‘Shadow Fleet’ Tankers for Oil Smuggling,” Baird Maritime, February 9, 2026, https://www.bairdmaritime.com/security/incidents/piracy/indian-coast-guard-detains-suspected-shadow-fleet-tankers-for-oil-smuggling These were the first interdictions against shadow vessels by India, a major recipient of oil transported by Russian shadow vessels, and may have been a gesture of goodwill toward the United States, which had, earlier that month, reduced its 50 percent tariffs on India to 25 percent.30White House, “Fact Sheet: The United States and India Announce Historic Trade Deal,” February 9, 2026, https://www.whitehouse.gov/fact-sheets/2026/02/fact-sheet-the-united-states-and-india-announce-historic-trade-deal/
In early March, Belgian forces, with some French air support, boarded the Ethera, a tanker sailing under a false Guinean flag, in Belgium’s EEZ in the North Sea.31“Belgian Soldiers Board Sanctioned Oil Tanker of Shadow Fleet,” Belgian Ministry of Defense, March 1, 2026, https://www.mil.be/nl/news/belgische-militairen-enteren-gesanctioneerde-olietanker-van-schaduwvloot/; and Kate Connolly, “Suspected Russian ‘Shadow Fleet’ Tanker Seized in North Sea,” Guardian, March 1, 2026, https://www.theguardian.com/world/2026/mar/01/suspected-russian-shadow-fleet-tanker-seized-north-sea A few days later, the Swedish Coast Guard detained the Caffa, a cargo ship also sailing under a false Guinean flag, in Swedish territorial waters.32Swedish Coast Guard, “Misstänkt statslöst fartyg bordat – utredningsåtgärder pågår,” March 6, 2026, https://www.kustbevakningen.se/nyheter/misstankt-statslost-fartyg-bordat–utredningsatgarder-pagar/ A few days after that, the Swedish Coast Guard detained another vessel sailing under a false flag. In both cases, the Swedish authorities detained crew members on suspicion of document falsification.33Swedish Coast Guard, “Intensivt utredningsarbete på Sea Owl I,” March 13, 2026. On April 3, the Swedish Coast Guard detained yet another shadow tanker, the false-flagged Flora 1, which was sailing off Sweden’s southern coast and had already caused an oil spill off the Swedish island of Gotland in the Baltic Sea.34“Kustbevakningen har bordat nytt fartyg – misstänks för brott,” SVT, April 4, 2026, https://www.svt.se/nyheter/lokalt/skane/kustbevakningen-har-bordat-nytt-fartyg On April 11, the Swedish Coast Guard boarded the Panama-flagged bulk carrier Hui Yuan of its southern coast. Although the Chinese-owned ship is not a ghost vessel, she too had been violating maritime rules by dumping Russian coal residue into the Baltic Sea on her way from Ust-Luga to Las Palmas in Spain.35“Bulkfartygets befälhavare har erkänt brott, fartyget får lämna Sverige,”36 Kustbevakningen (Swedish Coast Guard), April 12, 2026, https://www.kustbevakningen.se/nyheter/kustbevakningen-har-bordat-bulkfartyg-misstankt-for-brott-mot-miljobalken/
In March, the Irish government gave the Naval Service legal powers to board shadow vessels, though none have yet been boarded.37Conor Gallagher and Jack Horgan-Jones, “New Legal Powers Will Allow Naval Service to Board Vessels, Including Russia’s Shadow Fleet,” Irish Times, March 11, 2026, https://www.irishtimes.com/ireland/2026/03/11/new-legal-powers-will-allow-naval-service-to-board-vessels-including-russias-shadow-fleet/ The UK has also announced it will detain shadow vessels but has not yet done so.38Jack Fenwick, “UK Can Legally Stop Shadow Fleet Tankers, Ministers Believe,” BBC, January 11, 2026, https://www.bbc.co.uk/news/articles/cy8pn7jgy3no It has, however, provided support to French authorities in the detention of at least one such vessel.39“Royal Navy Joins French Operation against Sanctioned Russian Tanker,” UK Royal Navy, March 20, 2026,
https://www.royalnavy.mod.uk/news/2026/march/20/20260320-royal-navy-joins-french-operation-against-sanctioned-russian-tanker
Danish waters, a crucial passageway for vessels bound for Russian Baltic ports, saw 292 crossings by sanctioned vessels in 2025.40Malte Humpert, “Denmark Records 292 Russian ‘Shadow Fleet’ Tankers Passing through Danish Straits,” gCaptain (website), February 13, 2026, https://gcaptain.com/denmark-records-292-russian-shadow-fleet-tankers-passing-through-danish-straits/ That number is similar to observations in 2023 and 2024. Danish authorities have recently introduced innovative means to ensure these ships have a basic level of seaworthiness, and they have done so by taking port-state control to the sea. Port-state control (PSC) is the inspection of vessels by port officials when ships dock. In the international shipping system, ports are the de facto enforcement body insofar as one exists. Shadow vessels, however, travel through the Baltic Sea without docking at non-Russian ports.
That has prompted the new Danish measure. “We have introduced port-state control out at sea as a shadow fleet countermeasure. That means that sanctioned ships are going straight through, because we’re no longer giving them the possibility to get service at anchor since they face the risk of control. We did port-state control in this way on 122 ships last year,” said Brian Wessel, director-general of the Danish Maritime Authority. “But we don’t detain a lot of ships; five in 2025. We also check all the data with other countries and insurance companies, which means that we have a lot of data and a strong picture of the whole route, also outside Danish waters.”41Brian Wessel (director-general, Danish Maritime Authority), in discussion with the author, March 4, 2025. While Denmark’s small number of detentions may seem surprising given the considerable traffic through the country’s waters, it is perhaps understandable, as Russia has proven it is willing to exact revenge against detentions. Such behavior by Russia—and potentially other countries—puts smaller nations wishing to detain shadow vessels at a distinct disadvantage; every detention requires enormous courage because Russia can decide to retaliate anywhere, against anything, using any means.
Shadow vessel developments outside the Baltic Sea
The shadow vessels used by Iran, Venezuela, and North Korea have gained less attention than ones transporting Russian cargo—unsurprisingly so, as there are far fewer of them. In December 2025, however, the United States imposed a “blockade of all sanctioned oil tankers going into, and out of, Venezuela” and deployed Coast Guard vessels to the Caribbean, near Venezuela, to enforce the blockade.42“UN Experts Condemn United States Blockade and Aggression against Venezuela,” Office of the High Commissioner for Human Rights (OHCHR), United Nations, Press Release, December 24, 2025,
https://www.ohchr.org/en/press-releases/2025/12/un-experts-condemn-united-states-blockade-and-aggression-against-venezuela Experts from the United Nations Office of the High Commissioner for Human Rights noted that “there is no right to enforce unilateral sanctions through an armed blockade,” but the blockade remained and the US Coast Guard seized two shadow tankers.43“UN Experts Condemn,” OHCHR Press Release; and Max Matza, “US Seizes Second Oil Tanker Off Venezuela’s Coast,” BBC, December 21, 2025, https://www.bbc.co.uk/news/articles/c0mpy1ynnzzo;
In early January 2026, the Venezuelan shadow vessel Bella 1 broke through the blockade and began making her way across the Atlantic—chased by US Coast Guard and Navy vessels.44Matza, “US Seizes.” While en route, she changed her name to Marinera and, more crucially, she changed her flag status, from a false Guyanese registration to Russian flagging. A Russian Navy ship and submarine arrived to escort her.45“Coast Guard Cutter Munro Monitors Oil Tanker Bella 1 in North Atlantic Ocean,” Defense Visual Information Distribution Service, January 6, 2026, https://www.dvidshub.net/video/992486/coast-guard-cutter-munro-monitors-oil-tanker-bella-1-north-atlantic-ocean; and Jose M. Macias III, “What the Bella-1 Teaches Us About Targeting Shadow Fleets,” Center for Strategic and International Studies, January 8, 2026, https://www.csis.org/analysis/what-bella-1-teaches-us-about-targeting-shadow-fleets In the waters between Iceland and the UK, US forces boarded and detained the Marinera. Although the United Nations Convention on the Law of the Sea (UNCLOS) affords nations the right to detain ships sailing without flag registration outside their territorial waters, and the United States has a policy to act “in a manner consistent with its provisions relating to traditional uses of oceans,” the Marinera could point to its Russian flag registration.46U.S. Position on the U.N. Convention on the Law of the Sea, Office of the Staff Judge Advocate, Volume 97, 2021, https://digital-commons.usnwc.edu/cgi/viewcontent.cgi?article=2949&context=ils Had the Russian vessels decided to intervene, the situation would have escalated dramatically. US marines and sailors boarded another vessel several days later.47Heather Mongilio and Sam LaGrone, “Marines, Coast Guard Seize Tanker Olina in Caribbean,” USNI News, US Naval Institute, January 9, 2026, https://news.usni.org/2026/01/09/marines-coast-guard-seize-tanker-olina-in-caribbean Since then, the US has detained more Venezuelan shadow vessels. All were boarded outside US territorial waters, where UNCLOS would have given the United States the undisputed right to board.
Another development in shadow-vessel traffic unfolded after Iran effectively closed the Strait of Hormuz in the first week of March 2026. That meant that the tankers that transport oil, gas, and other commodities to international destinations could no longer leave or enter the Gulf. The week before the US-Israel attacks began, 38 percent of global crude oil, 29 percent of liquefied petroleum gas, 19 percent of liquified natural gas (LNG), and a variety of other cargoes passed through the Strait of Hormuz.48“Hormuz Shipping Disruptions Raise Risks for Energy, Fertilizers and Vulnerable Economies,” UN Trade and Development (UNCTAD), March 10, 2026, https://unctad.org/news/hormuz-shipping-disruptions-raise-risks-energy-fertilizers-and-vulnerable-economies That weekly flow translates to an average of 129 ships per day.49“Hormuz Shipping Disruptions,” UNCTAD. The following week, only between three and six ships transited the strait each day, primarily shadow vessels transporting Iranian oil.50“Hormuz Shipping Disruptions,” UNCTAD; and Lori Ann LaRocco, “Iranian Shadow Fleet and Greek Affiliated Ships Lead Strait of Hormuz Transits,” gCaptain, March 6, 2026, https://gcaptain.com/iranian-shadow-fleet-and-greek-affiliated-ships-lead-strait-of-hormuz-transits/ Presumably they had received assurances that Iranian forces would not target them. The war against Iran had thus become a lethal risk for legally sailing vessels but an advantage for Iranian shadow vessels, another development undermining the maritime order.
Effect on the shadow fleet
By early 2026, a strong dialectic was becoming clear within the shadow fleet: Baltic Sea coastal states—and some others, including France, Belgium, the United States, and India—were becoming more assertive in tackling the fleet, and shadow vessels, their crews, and owners were becoming more brazen.
In most cases, the coastal states acted in full compliance with UNCLOS. The actions by the United States, though, were more controversial as they were fighting fire with fire: combatting maritime rule violations with means that were themselves not fully compliant with maritime rules. As Stephanie Connor, a nonresident senior fellow at the Atlantic Council’s GeoEconomics Center, noted:51Stephanie Connor, “When Economic Warfare Meets Gunboat Diplomacy: What to Know About the US Seizures of Shadow Fleet Tankers,” Atlantic Council, February 5, 2026, https://www.atlanticcouncil.org/dispatches/when-economic-warfare-meets-gunboat-diplomacy-what-to-know-about-the-us-seizures-of-shadow-fleet-tankers/; M/T stands for motor tanker.
- Although US authorities have purportedly filed warrants to seize dozens more tankers linked to the Venezuelan oil trade, only two warrants have been unsealed to date: authorizations for the seizure of the M/T Skipper (previously known as the Adisa) and the Bella I (now known as the Marinera), both of which were sanctioned for their involvement in supporting Hezbollah and the Quds Force, one of the branches of Iran’s Islamic Revolutionary Guard Corps. … Sanctions alone do not authorize the seizure or confiscation of property.
Indeed, the US government used alleged actions related to terrorism—not sanctions evasion—as the legal basis for its pursuit of the Skipper and the Bella 1. From a US legal perspective, alleged terrorism-linked activities gives significant jurisdiction for civil forfeiture.52Special thanks to Celeste Kmiotek for clarifying this point.
Regarding the dramatic seizure of the Bella 1/Marinera, Rob McLaughlin of the University of Wollongong and Australian National University, and Conor McLaughlin of the Australian National Centre for Ocean Resources and Security observe that the US government’s rejection of the Bella 1/Marinera’s en route reflagging to Russia is difficult to accept given Russia’s confirmation of this transfer. They add:
- It is of course possible that the United States has other information that undermines the Russian claim. But on the publicly available information at the moment, the Russian claim of flag state jurisdiction, and thus protection rights over the Marinera, based on fulfillment of Russian domestic law requirements for registration and the limited international law approach to genuine link, appears to be effective.53Rob McLaughlin and Conor McLaughlin, “A Law of the Sea Assessment of the U.S. Boarding of the Bella 1/Marinera,” Just Security, January 14, 2026, https://www.justsecurity.org/128760/law-sea-assessment-boarding-bella1-marinera/
Another development plays a role in the evolution of the shadow fleet: the price of oil. Until March 2026, the price had been comparatively low—so low that, in January 2026, the coalition that imposed the price cap in December 2022 lowered it from $60 to $44.10 per barrel.54European Commission, “New Dynamic Mechanism to Lower Price Cap for Russian Crude Oil to $44,10 per Barrel,” Directorate-General for Financial Stability, Financial Services and Capital Markets Union, January 15, 2026, https://finance.ec.europa.eu/news/new-dynamic-mechanism-lower-price-cap-russian-crude-oil-4410-barrel-2026-01-15 On December 31, 2025, Brent crude averaged $61 per barrel.55“Brent Crude Oil,” Trading Economics, Price Chart, https://tradingeconomics.com/commodity/brent-crude-oil Still, the lower price meant Russia had to export more oil to reach the desired revenue. Wessel describes the impact:56Wessel interview with the author.
- The number of Russian shadow vessels is not decreasing but increasing, because with the oil price down 30 to 40 percent the Russians are pressured and need to export more. It’s also increasingly difficult for them to operate their shadow fleet, and therefore they have to broaden it and to get more ships to export the same amount. Chinese and the Indians are still buying Russian oil. But the hassle Russia has in getting its oil around the world is increasing.
- I wouldn’t have said this three, four months ago, but now I can say that our efforts are working and it’s really difficult for the Russians, and they’re getting less revenue for their oil.
That is, of course, precisely what the price cap was designed to achieve.
But the oil market has changed since the author interviewed Wessel on March 4, 2026—with the price of oil rapidly rising as a result of the de facto closure of the Strait of Hormuz. By early April, it had reached $109 per barrel, which made oil transport on shadow vessels extremely lucrative.57“Brent Crude Oil,” Trading Economics. (The announcement of the ceasefire on April 7 caused the price to drop, but as this report is finalized on April 10, the ceasefire appears fragile, and the oil price is rising once again.)
In response to the global oil crisis triggered by the war in Iran, the United States lifted its sanctions on Russian oil.58“GENERAL LICENSE 134 Authorizing the Delivery and Sale of Crude Oil and Petroleum Products of Russian Federation Origin Loaded on Vessels as of March 12, 2026,” Office of Foreign Assets Control, US Department of the Treasury, https://ofac.treasury.gov/media/935191/download?inline At the time of writing, this means that legally sailing vessels can transport Russian crude above the price cap without violating US rules, though this would still be a violation of the price cap imposed by the G7 and the EU.
Increased Russian links to the shadow fleets
For the first nearly two and a half years of reliance on the shadow fleet, Russia did not acknowledge its links to it. That changed with Estonia’s attempted detention of the Jaguar and the Russian Air Force’s menacing intrusion into Estonian airspace. Since then, Russian military vessels have, as previously noted, begun to regularly escort shadow vessels through the Baltic Sea and the English Channel.
Russia has also formalized its links to the shadow fleet in other ways. While in the early months and years shadow vessels mostly sailed with illegitimate or useless insurance certificates, by early 2026 official—but sanctioned—Russian insurers were increasingly underwriting shadow vessels transporting Russian cargo. In late February 2026, around one-third of all oil tankers crossing the Baltic presented insurance certificates from sanctioned Russian or Russian-linked insurers.59Richard Meade, “One in Three Baltic Tanker Transits Are Covered by Russian Insurance,” Lloyd’s List, February 26, 2026, https://www.lloydslist.com/LL1156459/One-in-three-Baltic-tanker-transits-are-covered-by-Russian-insurance
Russia is also beginning to flag more tankers. The Russian Maritime Register of Shipping, itself under EU sanctions, “is preparing to identify and inspect approximately 80 tankers in the near term, with the aim of re-registering them under the Russian flag,” Euromaidan Press reports, citing Ukraine’s Foreign Intelligence Service. The vessels included in the plans are currently flagged in the Seychelles (thirty-five ships), China (twenty-three), Azerbaijan (thirteen), and Samoa (eight), with additional tankers registered to owners in Vietnam, India, the United Arab Emirates, and the Marshall Islands, the news outlet reports.60Maria Tril, “Russia Plans to Re-register 80 Shadow Fleet Tankers under Its Own Flag to Evade Western Sanctions, Ukraine Intelligence Says,” Euromaidan Press, March 13, 2026, https://euromaidanpress.com/2026/03/13/russia-plans-to-re-register-80-shadow-fleet-tankers-under-its-own-flag-to-evade-western-sanctions-ukraine-intelligence-says/ It is unknown how many of them are shadow vessels, but the fact that Russia plans to flag more tankers suggests it is committed to continued export of oil under any circumstances and is planning to take action against coastal states trying to detain tankers.
Unconventional responses to shadow vessels
Ukraine is the Russian shadow fleet’s main victim, as proceeds from the oil exported by the shadow vessels fund Russia’s war against Ukraine. Unsurprisingly, Ukraine has long sought to combat the Russian shadow fleet, and starting in 2025 it has done so in unconventional ways. In November 2025, drones thought to have been fired by Ukraine struck the shadow tankers Kairos and Virat off the Turkish coast in the Black Sea.61Danny Aeberhard and Tom Bennett, “Ukraine Hits Tankers in Black Sea in Escalation against Russia,” BBC, November 30, 2025, https://www.bbc.co.uk/news/articles/cp9ky5z2gx0o The following month, drones also thought to have been fired by Ukraine struck the Oman-flagged shadow tanker Qendil, en route to Port Said in Egypt, in the Mediterranean, some 2,000 kilometers from Ukraine.62“Burn, Sea Baby, Burn,” Opinion, Lloyd’s List, December 19, 2025, https://www.lloydslist.com/LL1155929/Burn-Sea-Baby-burn The same month, the Comoros-flagged shadow tanker Dashan was struck—again reportedly by Ukrainian drones—near the Russian port of Novorossiysk.63Sherie Ryder, “Russian Shadow Fleet Tanker Targeted by Ukrainian Sea Drone,” BBC, December 11, 2025, https://www.bbc.co.uk/news/live/cz941j0l48et
In March 2026, the China-bound shadow vessel Arctic Metagaz, which was carrying Russian liquefied natural gas and navigating with its automatic identification system turned off, exploded off the coast of Malta. Russian authorities blamed the incident on Ukrainian drones.64Herman Grech and Christopher Scicluna, “Russian Gas Tanker Explodes between Malta and Libya,” Times of Malta, March 3, 2026, https://timesofmalta.com/article/russialinked-gas-tanker-ablaze-150-miles-off-malta.1124914 The attack put the ship adrift and it was on the verge of sinking, which posed an “imminent and serious” ecological threat, European officials warned.65“Russian ‘Shadow Fleet’ Gas Tanker Adrift in Mediterranean Poses ‘Imminent and Serious’ Threat, EU States Say,” Sky News, March 16, 2026, https://news.sky.com/story/russian-shadow-fleet-gas-tanker-adrift-in-mediterranean-poses-imminent-and-serious-threat-eu-states-say-13520686 On April 2, authorities in Libya—into whose search-and-rescue waters the ship had drifted—announced that a towing operation had failed and that the ship was “completely out of control at sea.66”Malte Humpert, “Libya Confirms ‘Arctic Metagaz’ Salvage Has Failed and Vessel Out of Control at Sea Near Malta SAR Zone,” gCaptain, April 2, 2026, https://gcaptain.com/libya-confirms-arctic-metagaz-salvage-has-failed-and-vessel-out-of-control-at-sea-near-malta-sar-zone/ In late March, Ukraine struck the oil and gas terminal in the Russian port of Ust-Luga on two occasions using long-range drones, the Security Service of Ukraine (SBU) announced. The attacks caused serious damage and fire to the port, which caused serious disruption to Russian oil exports.67Asami Terajima, “’Serious Damage:’ Ukrainian Drones Deal Fresh Blows to Russia’s Ust-Luga Port, SBU Says,” Kyiv Independent, March 29, 2026, https://kyivindependent.com/russian-governor-reports-fire-at-ust-luga-port-amid-ukrainian-drone-strike/ It also caused a significant backup of shadow vessels in the Gulf of Finland.
While understandable from a moral and national security perspective, the Ukrainian attacks pose a dilemma for policymakers from Europe and other countries allied with Ukraine, as they appear unlawful and could be used by Russia as a pretext for further escalation. Indeed, in mid-March 2026 a top Russian official said Russia is considering deploying naval “mobile firing groups” to escort merchant vessels.68“Russia Considers Sending Armed Naval Patrols to Protect ‘Shadow Fleet,’” Financial Times, updated March 18, 2026, https://www.ft.com/content/6ba075d8-890b-40d8-a1a8-8be8ad250822
Conclusion
Baltic Sea coastal states, the countries most affected by the shadow fleet, have made considerable strides in tackling the dangerous and disruptive fleet. They have done so to uphold maritime order and protect their waters from accidents that could pose significant harm to other ships and to marine life, and for the most part, their actions have been in full compliance with UNCLOS.
Regrettably, they now face a situation in which shadow vessels, their crews, their owners, and the Russian state do not comply with coastal states’ enforcement of maritime rules but instead opt for escalation. Such escalation involves even more brazen behavior by the ships as well as menacing escorts and other “protective” activities by the Russian state. The shadow fleet’s new behavior and Russia’s involvement in it may, in fact, be the most pronounced example of the breakdown of the rules-based international order—even amid proliferating rule violations in different parts of the world.
Detentions of shadow vessels by the United States undermine these activities. Though there is no doubt that Venezuela has relied on shadow vessels, especially for exports of oil, the US pursuit of Venezuelan-linked shadow vessels has gone to the limit of or beyond what is permitted under UNCLOS. Although the United States has not signed UNCLOS, it has long adhered to it and, in fact, acted as the key protector of several of its pillars, most especially freedom of navigation. A more constructive approach might have been to work with the countries whose ports the Venezuelan-linked shadow vessels use, or whose waters they traverse, to push for proper port-state control or detention.
Even so, coastal states and other UNCLOS signatories should remain firm in their commitment to rules-based enforcement of maritime rules. Enforcement that violates UNCLOS would trigger a race to the bottom.
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Image: The oil tanker Marinera, previously known as Bella 1, which was seized by the US Coast Guard, is moored in the Moray Firth, off the coast of Scotland on January 14, 2026. (REUTERS/Russell Cheyne)

