Russia's shadow fleet in the Baltic, 2024-2026

Russia's 'shadow fleet' -- tankers that operate outside Western-regulated insurance, classification and flag oversight to move sanctioned oil -- is not one static list; it is a moving target that different trackers size very differently. By June 2026 sanctioned 'shadow' tankers carried 54% of all Russia's seaborne oil (66% of crude specifically), even as roughly a third of Russia's export tonnage had shifted back onto G7-linked, insured ships that month. Estimates of the fleet's total size range from 600-1,000 ships to over 3,000, depending on definition.

Each package layers in more than vessel names. The 18th package (Jul 2025) cut the G7 oil price cap from $60 to $47.6/barrel; the 19th (Oct 2025) banned reinsuring shadow-fleet vessels outright; the 20th (Apr 2026) activated the EU's 'anti-circumvention tool' for the first time and reached a third-country port (Karimun, Indonesia) for the first time; and by the 21st package (Jul 2026) the price-cap adjustment mechanism itself was frozen until mid-2027 to stop Russia benefiting from a Strait-of-Hormuz-driven price spike.

Being on a sanctions list did not, for most of 2025, mean a ship would actually be stopped. That changed in 2026. On 14 June 2026, Royal Marine Commandos fast-roped onto the tanker Smyrtos in the English Channel -- the UK's first physical boarding of a shadow-fleet vessel, three months after London first announced it would board sanctioned ships transiting its waters. Opposition MPs pointed out that in those three months, at least 94 shadow-fleet transits of UK waters had gone unchallenged.

The UK is not acting alone. EUNAVFOR MED IRINI -- created to police Libya's arms embargo -- and Operation ATALANTA both gained Article-110 flag-verification boarding authority in 2026 and used it well outside the Baltic: IRINI's sixth such boarding, of the tanker Sun off Italy on 30 August 2026, came after earlier boardings of the Toa Payoh and South Star. France separately detained the tankers Tagor and Deliver in June 2026 for false Cameroonian-flag claims. The common legal thread across all of these is the same one used against the Smyrtos: a vessel with no genuine flag has no right to innocent passage.

The clearest illustration of how hard the fleet is to pin down is a single hull. Estonia's Navy detained the tanker Kiwala in April 2025 after finding its Djibouti flag registration had lapsed -- but released it two weeks later once Djibouti agreed to provisionally re-accept it. By September 2025 the same hull, now called Pushpa, loaded 750,000 barrels of Russian crude at Primorsk and was named as a suspect in a Copenhagen drone incident three days later; days after that, France detained it off Saint-Nazaire under a third name, Boracay. Analytics firm Windward counted five names, seven flags, four owners and nine managers for this one vessel since late 2022.

The Eagle S case shows the opposite failure mode: a clean detention that still collapsed legally. Finland held the tanker after it dragged its anchor 90km across the Gulf of Finland on Christmas Day 2024, severing the Estlink 2 power cable. But in October 2025 a Finnish court dismissed all charges, ruling that under UNCLOS such 'incidents of navigation' can only be prosecuted by the ship's flag state (Cook Islands) or the crew's own countries -- not Finland. The crew went home; no charges were ever brought against the owner.

Estonia's May 2025 attempt to inspect the tanker Jaguar went further still: when the ship ignored the order, a Russian Su-35 briefly entered Estonian airspace with its transponder off to shield it, prompting a NATO F-16 response -- Estonia's first reported Russian airspace violation that year. Weeks later, Poland intervened when a tanker sailing as 'Sun' made suspicious moves near the Poland-Sweden power cable; Warsaw sent a patrol aircraft and the survey vessel ORP Heweliusz rather than attempting a boarding.

Short of a boarding, Baltic states have leaned on insurance-document checks. Finland has demanded CLC pollution-liability certificates from Russia-origin tankers since December 2024; Denmark added Port State Control-style environmental checks outside Skagen from October 2025, funded through its 2026 budget. Denmark's own count: 292 sanctioned-tanker voyages through its straits in 2025 alone -- the volume any Baltic insurance-checkpoint regime has to process.

Sweden's Navy confirmed in December 2025 that armed personnel -- likely private contractors -- are stationed aboard some shadow-fleet tankers, alongside a more constant Russian naval presence near Baltic shipping lanes. By April 2026, Ukrainian drone strikes on Primorsk and Ust-Luga had left 30-40 tankers idling empty in the Gulf of Finland, and Estonia's own naval commander told Reuters that after Russia scrambled a fighter jet to shield one inspection attempt, the escalation risk of detaining vessels in Estonia's own waters was now 'too high' -- intervention would be reserved for an imminent spill or infrastructure damage.

This is where the underwriting reality diverges most sharply from the sanctions-list narrative. KSE Institute's Feb 2025 survey of the roughly 14,000-vessel global tanker fleet found insurance status verifiable for only 63.5% of ships; among tankers that carried oil in 2024, only 29.4% of those carrying Russian crude held recognized International Group P&I cover, against over 90% for tankers carrying no Russian cargo at all. Non-IG-insured vessels were, on average, nearly four years older and far more likely to fly a grey- or black-listed flag.

The legal backstop for an uninsured spill is the 1992 Civil Liability Convention (CLC) and its IOPC Fund, which can pay up to roughly $279 million per incident once an owner's own liability cap is exhausted -- a system that worked after the Prestige and the Hebei Spirit. Between 2024 and mid-2025, Estonia and Finland radioed insurance-document demands to over 2,000 tankers; more than 90% produced some certificate, but roughly a third of those came from sanctioned Russian insurers, and no government has said how many of the rest were ever verified as real.

In mid-2026 the theoretical gap became an actual spill. The Caroline Bezengi, a 2001-built Suezmax carrying 800,000 barrels of Russian Urals crude, suffered an engine-room explosion off Yemen on 8 June 2026 and grounded on 30 June inside a 667km² Omani marine reserve. By mid-August, estimates of the oiled area ranged from 390km² (Oman's own Environment Authority) to over 2,000km² (independent satellite analysis) -- itself a sign of how little verified data exists once a shadow tanker is in trouble.

Making matters worse, the IOPC Fund told Reuters in August 2026 that it would not contribute, treating the loss as an 'act of war' -- a category the 1992 Convention excludes from compensation, but one the Fund had not yet formally ruled on. IOPC Funds delegates had already warned in November 2025 that shadow-fleet vessels pose a systemic risk to the compensation system itself, not just to individual coastal states -- Caroline Bezengi is the first live test of that warning.

Cameroon illustrates the cycle well. By early 2026 it had quietly become the shadow fleet's second-largest flag registry -- behind only Russia's own flag -- peaking at 143 sanctioned tankers in February 2026, until its own investigation found its flag was being sold through fraudulent websites. Cameroon suspended new registrations on 6 February 2026 and told the IMO in June it had struck 39 ships from its registry, with its sanctioned-tanker count falling from 141 (end-April) to 116 (end-June). A single Dubai-based operator that ran both the Gabon and Comoros registries became the first registry manager sanctioned by the EU and UK; both registries have since been emptied of sanctioned tonnage.

Displaced tonnage does not disappear -- it moves. Panama, once the single largest shadow-fleet flag with 193 sanctioned tankers, deregistered over 650 vessels since 2019 and now flags only 14; Equatorial Guinea, by contrast, grew from 2 sanctioned tankers in December 2025 to 27 by June 2026, the fastest growth of any flag. Even landlocked Malawi -- which has no maritime registry at all -- had its name used on fraudulent certificates throughout 2025. Increasingly, expelled vessels skip smaller registries altogether and simply re-flag as Russian, whose sanctioned-tanker count grew from 125 to 219 in eighteen months -- not coincidentally, a genuine Russian flag defeats the 'stateless vessel' legal basis Western navies use to justify boarding.

Sanctions pressure and price-cap enforcement are visibly biting at the margin, even if Russia's overall export machine keeps running. In June 2026 the price cap itself was cut to $44.1/barrel, yet Urals crude still averaged $63.18 -- 43% above the cap -- while the discount to Brent held flat at $24/barrel. CREA calculates that full enforcement of even the current cap would have cost Russia 36% of that month's revenue; a $30 cap, its recommended level, would have cost 39% cumulatively since December 2022.

New-vessel recruitment into the Russia-serving shadow fleet has slowed markedly: only 3 new 'shadow' vessels joined Russian routes in June 2026, versus 8 tankers that carried Russian crude for the first time since 2020 that month -- 7 of them G7+-linked, hinting that some tonnage is drifting back toward compliant, insured shipping even as the hard core of 157 shadow tankers (42% of them 20+ years old) keeps running.

NATO's Baltic Sentry, launched in January 2025 under Allied Joint Force Command Brunssum, followed Germany's stand-up of Commander Task Force Baltic (CTF Baltic) at Rostock three months earlier. Its founding joint statement explicitly named the shadow fleet as a Baltic-wide security and environmental threat and committed allies to more insurance-certificate inspections -- language that anticipated, by a year, the insurance-checkpoint regimes Finland and Denmark later stood up unilaterally.

A few figures in this space simply disagree across otherwise credible sources. UK vessel counts range from 'over 550' to 'more than 600' depending on whether Arctic LNG tankers are included. Estimates of the shadow fleet's total size range from 600-1,000 ships to over 3,000. And this run could not verify a Dec-2024 IMO resolution matching the research brief's anchor -- the only directly-confirmed IMO shadow-fleet resolution (A.1192(33)) dates to Dec 2023, one year earlier; a genuine Dec-2024 IMO Legal Committee proposal exists but was not independently opened as a primary document in this run.

Enforcement architecture is still visibly improvised rather than settled. Estonia's Riigikogu gave its own Defence Forces the legal power to sink a threatening vessel as early as April 2025, yet Estonia's navy commander said a year later that the escalation risk of even a routine detention was 'too high.' The UK spent three months sitting on a boarding authorization before using it once. And EUNAVFOR MED IRINI's boarding authority, aimed at the shadow fleet, is being exercised in the Mediterranean, not the Baltic -- geography, not the sanctions list, increasingly decides which navy can act.

• Whether the Fitburg trial (opened 8 Sep 2026 in Helsinki, two days before this research run) results in a conviction, and whether it changes how Baltic states charge anchor-drag cases after the Eagle S dismissal.
• Whether Oman succeeds in forcing the IOPC Fund's 'act of war' exclusion to a legal test within its three-year window.
• Whether Equatorial Guinea faces the same EU/UK sanctioning of its registry operator that ended Cameroon's, Gabon's and Comoros's runs as flags of choice.
• How many of the roughly 2,000+ insurance certificates Estonia and Finland have collected since 2024 have actually been verified as genuine, rather than merely 'produced.'