Forty ships accused of belonging to a large “shadow fleet” moving sanctioned oil for Venezuela and others were reflagged to Russia last year in an apparent attempt to gain Kremlin protection from American seizure.
Analysis by the shipping intelligence publication Lloyd’s List suggests that of those, at least 17 suspicious vessels joined the Russian registry over the past month, compared with 15 ships in the previous five months of 2025.
The sudden flurry of activity appears to be linked to Donald Trump’s announcement last month of what he called a US “blockade” of sanctioned oil tankers in and out of Venezuela.
The term “shadow fleet” is defined by Lloyd’s List as ships for which deceptive practices are used in order to allow them to transport goods – including oil and gas – in violation of sanctions and price caps.
On Thursday, a ship subjected to sanctions by the US over concerns it had been involved in distributing illicit Russian oil was identified as sailing through the Channel under a false name and Cameroonian flag. Tracking data suggested it was heading towards Russia after departing from the Star Rafineri refinery, near İzmir, western Turkey, on 30 December.
In 2024, only 18 ships identified as being part of the shadow fleet were thought to have changed their national registration to take the Russian flag, but Trump’s interest appears to have drawn many others to make the move.
Before its dramatic seizure by US special forces on Monday, the tanker Marinera carrying Venezuelan oil was known as the Bella 1. It had sought to evade American intervention by switching its flag from a falsified Guyanese flag to a Russian flag, a crude image of which had been painted on its side.
The tactic failed to protect Marinera – or a second vessel, known as M/T Sophia, which was seized in the Caribbean and escorted to the US by the coastguard on the grounds that it was conducting “illicit activities”.
In early December, US special forces also seized the Skipper, a tanker off Venezuela that the US treasury had placed under sanctions in 2022 after claims it had been smuggling oil on behalf of Iran’s Revolutionary Guards and Hezbollah.
Bridget Diakun, a senior risk and compliance analyst at Lloyd’s List Intelligence, said that as of October there were 1,423 ships within the shadow fleet suspected of moving sanctioned goods for Russia, Iran and Venezuela.
The fleet was growing by about 10 vessels a month, the data suggested. In recent weeks there had been a sudden trend towards some of those ships applying to join the Russian registry, Diakun said.
Russia had reportedly dispatched a submarine to escort the Marinera in the days before it was boarded by US special forces, and the Kremlin had warned the White House off from intervening.
According to analysis by the Center for Strategic and International Studies, Russia’s shadow fleet transports an estimated 3.7m barrels of oil a day, representing 65% of Russia’s seaborne oil trade, and generates an estimated $87bn (£69bn) to $100bn (£80bn) annual revenue.
On Thursday, Douglas Alexander, the secretary of state for Scotland, defended the UK’s involvement in the seizure of the Marinera after Russia claimed that this was a breach of the 1982 UN Convention on the Law of the Sea.
Alexander said: “This ship is part of the shadow fleet that funds Russia’s war effort in Ukraine.
“As a UK government and as the United Kingdom, our national interest is served by avoiding the illegal fuelling of terrorism, of conflict and of misery, whether in Ukraine, the Middle East or anywhere else. So when we were asked by the United States to provide operation assistance, including basing an air surveillance support, we were absolutely willing to step up.
“I think it is right and reasonable we work with our allies to confront the attempt to sanction-bust that we are witnessing from the Russians on a regular basis.”
