Europe’s blind spot: how Russian-linked oil trade continues off the EU’s Black Sea coast

In the final days of October 2025, maritime tracking data once again captured a scene that has become quietly familiar in the Black Sea. A tanker identified as Nikolay Gamayunov was observed moving slowly in international waters roughly 50 nautical miles east of the Bulgarian port city of Varna. For several hours, the vessel remained in the same area, before at least one other commercial ship approached and stayed alongside it.

Such side-by-side positioning at sea is a recognised indicator of ship-to-ship operations, commonly used for refuelling or transferring cargo without entering port. The activity took place beyond Bulgaria’s territorial waters, but close to the EU coastline – in a stretch of sea that lies just outside routine port controls and just inside a zone of fragmented and overlapping institutional responsibility.

On its own, the encounter could have been dismissed as an unremarkable detail of maritime traffic in a busy corridor. Similar meetings happen daily across the world’s oceans. What makes this one different is context.

The tanker involved, Nikolay Gamayunov, appears in War & Sanctions, a public database maintained by Ukraine’s military intelligence. The database tracks vessels linked to the transport of Russian oil and petroleum products since the start of the war in Ukraine. According to its records, the ship has repeatedly sailed to Russian Black Sea ports, has been documented switching off its Automatic Identification System (AIS) during voyages, and has previously called at ports in occupied Crimea.

The October 2025 sighting was therefore not simply an isolated maritime episode. It was the latest visible expression of a pattern that has been unfolding along the EU’s Black Sea frontier since at least 2023 – a pattern in which Russian-linked oil trade continues to adapt, offshore, to the constraints imposed by European sanctions.

The same moves, one year earlier: 2024

Tracking records from 2024 show that Nikolay Gamayunov was not alone. A near-identical tanker, Nikolay Velikiy, followed similar routes and displayed similar behaviour. Both vessels regularly sailed from Russian ports such as Novorossiysk, then slowed or anchored for extended periods in waters off Varna and Burgas.

Investigative reporting in Bulgaria documented multiple instances in which commercial ships departed Bulgarian ports, sailed directly to one of the tankers offshore, remained alongside it for hours, and then returned to port. While none of these movements, taken individually, constitutes proof of wrongdoing, Bulgarian authorities themselves acknowledge the limits of what they can verify.

In written responses to journalists, the Customs Agency stated that it had no data on fuel deliveries from the named tankers to Bulgarian ports and that no violations had been established within its remit.

The Maritime Administration confirmed that its role is limited to navigational safety and the authorisation of specific operations, not to oversight of the commercial parameters or origin of cargo transferred offshore.

Publicly available vessel-tracking data also show repeated gaps in the AIS signals of the tankers during these voyages. Under international maritime rules, AIS is intended to remain active at all times, except in narrowly defined circumstances related to safety. Extended or repeated shutdowns are widely regarded by regulators and sanctions-monitoring bodies as a warning sign – particularly in regions where sanctions evasion has already been documented.

By 2024, the pattern was already established: Russian-linked tankers loitering just beyond territorial waters, intermittent visibility on tracking systems, and repeated encounters with EU-bound vessels – all taking place in a zone where no single authority claims comprehensive oversight.

How the mechanism works

Ship-to-ship transfers are not, in themselves, illicit. They are a routine feature of global shipping, used to reduce congestion in ports or optimise logistics. In a sanctioned environment, however, the same technique can be repurposed to blur lines of accountability.

By transferring fuel or cargo offshore, vessels can avoid port inspections, customs checks and, in some cases, taxation. Conducting such operations just outside territorial waters adds an additional layer of complexity. In the contiguous zone – which extends up to 24 nautical miles from shore – coastal states may enforce certain laws, but continuous surveillance is rare and enforcement powers are often less clearly defined.

The Black Sea’s geography amplifies these effects. Narrow, busy and bordered by multiple jurisdictions, it offers ample opportunities for vessels to operate in spaces where oversight is partial and fragmented.

AIS shutdowns further complicate matters. When a ship temporarily disappears from tracking systems, the public record of its movements breaks. Where it went, which vessels it met, and what transfers may have taken place during that period become difficult, if not impossible, to verify after the fact.

The system does not depend on secrecy. It depends on ambiguity.

Why oversight fails – by design

The persistence of offshore transfers near EU shores is often framed as a failure of enforcement. In practice, it is more accurately described as a consequence of institutional design.

In Bulgaria, responsibility for maritime activity is divided among several agencies. The Customs Agency monitors goods entering ports. The Maritime Administration regulates navigational safety and authorises specific operations. Border police patrol territorial waters. Environmental inspectorates respond to pollution incidents.

In responses to media inquiries conducted between 2023 and 2025, all of these institutions consistently stated that they had no evidence of violations within their respective jurisdictions. At the same time, none disputed that offshore encounters between commercial vessels were taking place.

What emerges from these official positions is not a dispute over facts, but a division of responsibility so narrow that no institution retains sight of the full transaction.

The economics of the grey zone

The incentives that sustain offshore activity are straightforward.

In EU member states, marine fuel prices include excise duties and value-added tax. Together, these can account for a significant share of the final price. Offshore sales conducted beyond national tax regimes can therefore be markedly cheaper.

For shipping companies operating on tight margins, the difference is substantial. Offshore refuelling undercuts compliant suppliers and distorts competition, creating a powerful incentive to seek fuel at sea rather than in port.

These incentives intensified after the European Union banned seaborne imports of Russian crude oil in December 2022, followed by a ban on most refined petroleum products in February 2023. The introduction of a G7-backed price cap further reshaped the market.

Demand did not disappear. It adapted.

A parallel case: crude oil off Burgas (2023-2024)

The same structural vulnerabilities are visible further south, near Bulgaria’s largest oil refinery in Burgas.

Throughout 2023 and 2024, tankers were repeatedly observed conducting ship-to-ship transfers of crude oil in the waters off the city. Unlike the bunkering operations off Varna, several of these transfers were formally authorised by the Maritime Administration, carried out under pilot supervision and with tugboats equipped for spill response on standby.

Their legality was not disputed. Their consequences were.

From early 2024, residents of Burgas (the second largest port on the Bulgaria’s Black Sea coast|) and nearby coastal towns such as Chernomorets and Sozopol began reporting persistent petroleum odours drifting inland from the sea.

In official responses, the Regional Environmental Inspectorate confirmed receiving complaints, but stated that it lacked the technical equipment to measure all relevant volatile compounds and could not conclusively link the odours to specific offshore operations.

In July 2024, the government introduced a ban on ship-to-ship transfers within 35 kilometres of Burgas Bay. In the weeks that followed, journalists analysing vessel-tracking data documented further offshore encounters closer to shore than the permitted limit. Authorities stated that no formal violations had been established.

Although these operations involved crude oil rather than marine fuel, the regulatory logic remained unchanged: offshore transfers assessed individually, without cumulative oversight of their broader economic, environmental or sanctions-related impact.

What this means for Brussels

For the European Union, the significance of what is happening in the Black Sea goes well beyond the behaviour of individual vessels or the capacity of individual coastal states. It strikes at the core assumption underpinning the EU’s sanctions regime: that compliance can be monitored, verified and enforced through a combination of national authorities acting within a shared legal framework.

In practice, maritime enforcement remains overwhelmingly national, while the trade it seeks to regulate is transnational by design. Ships flagged in one country, owned through shell companies in another, insured – if at all – in a third, and operating just outside territorial waters expose the limits of a system that relies on coordination rather than command.

Brussels has tools at its disposal. The European Commission oversees sanctions policy. The European Maritime Safety Agency (EMSA) operates satellite-based monitoring systems capable of tracking vessels and detecting anomalous behaviour. EU agencies routinely share data on land borders and in airspace. At sea, however, these capabilities are unevenly integrated into enforcement practice.

What the Black Sea cases illustrate is not a lack of information, but a lack of institutional synthesis. Data exists, but they are scattered across agencies, jurisdictions and mandates. No EU-level body is tasked with assembling these data into a continuous operational picture of sanctioned maritime trade.

This gap has consequences. When enforcement depends on coastal states acting alone, disparities in capacity and political pressure become decisive. Areas with limited resources or heightened economic dependence on maritime trade risk becoming de facto pressure valves for the entire sanctions system.

For Brussels, the question is no longer whether sanctions are being circumvented – that much is widely acknowledged – but whether the EU is prepared to treat maritime enforcement as a collective responsibility rather than a coastal inconvenience.

What this reveals – and why it matters

The offshore activity observed near Varna and Burgas does not amount to a single, neatly defined violation of European law. It reveals something more complex and, in many ways, more troubling: a system that allows sanctioned trade to persist not through concealment, but through fragmentation.

European sanctions are designed on the assumption that trade flows can be traced, verified and, if necessary, interrupted. That assumption holds on land, where borders are fixed and customs authorities operate within clearly defined jurisdictions. At sea, it breaks down. Jurisdiction shifts by the mile, mandates overlap without aligning, and responsibility disperses across institutions that rarely share a common operational picture.

In this environment, compliance becomes a matter of interpretation rather than enforcement. Vessels may technically remain outside territorial waters. Transfers may be authorised individually while escaping cumulative scrutiny. AIS signals may be switched off without triggering automatic intervention. Each element, viewed in isolation, can be explained. Taken together, they form a system that is resilient to oversight.

The implications extend beyond sanctions policy. Offshore bunkering and ship-to-ship transfers conducted without effective monitoring distort markets, undermine legitimate operators and erode trust in regulatory frameworks. Over time, they normalise a form of economic activity that depends on ambiguity as a business model.

There is also a political cost. Sanctions are a statement of collective intent. When their enforcement appears uneven or porous, that intent is weakened — not only in the eyes of those targeted, but among the states tasked with upholding it.

Unless Europe develops mechanisms capable of seeing maritime trade as a continuous process rather than a series of disconnected checkpoints, the pattern documented in October 2025 is likely to repeat. The sea will remain a space where accountability fades with distance from shore, and where the line between legality and evasion is defined less by rules than by the gaps between them.

This article is part of the Bulgaria International Journalism Fellowship (BIJF), and implemented by AUBG’s Center for Information, Democracy, and Citizenship (CIDC).

Caption: The position of the tanker “Nikolai Gamayunov” on 31 October2025. The data in the right box shows that the ship’s last port of call was Novorossiysk, but it is not traveling anywhere. [Map: VesselFinder. Image: Dnevnik, partner of EUalive]

• Black Sea
• EU sanctions
• investigative journalism
• Russian oil

Updated: January 7, 2026 - 10:57