Vladimir Putin has ramped up Russia’s use of its so-called shadow fleet to circumnavigate Western sanctions, an expert has warned. The issue has been of growing concern this year, with vessels believed to be part of the Kremlin’s shadow fleet linked to drone incursions and accused of severing undersea cables in Europe.

The vessels are typically ageing oil tankers with murky ownership and dubious flagging. Gonzalo Saiz Erausquin, research fellow at the Royal United Services Institute think tank, said while the shadow fleet is not a new threat, it is playing an increasingly significant role. He said it “expanded drastically” following Russia’s full-scale invasion of Ukraine in February 2022.

The expert told The Guardian: “That saw what we call the shadow fleet explode to some 900-1,200 vessels globally.

“It is not highly structured or homogeneous. These are vessels that Russian interests are able to purchase secondhand, opaquely owned tankers or owned by companies prepared to engage in illicit activity.”

The fleet has an illicit network supporting it, including a rise in fake flag registration websites and opaque companies that will facilitate trade, The Guardian reported.

Iran and Venezuela are said to be taking inspiration from Russia’s shadow fleet.

The three nations are allegedly shipping cargo to customers including India and China.

Earlier this week, the EU slapped sanctions on 41 more vessels that it said were part of Moscow’s shadow fleet, bringing the total number to almost 600.

Experts have expressed concern that increased efforts to police the shadow fleet could spark confrontations, with signs suggesting Russia is willing to use its military to protect the tankers.

These concerns were highlighted further on Friday after Ukraine struck a suspected shadow tanker with drones in the Mediterranean.

While on Tuesday, Donald Trump said he was ordering a “blockade” of sanctioned oil tankers leaving and entering Venezuela.

On Saturday, a tanker — reportedly not on the US Treasury list of sanctioned vessels — was seized in international waters by American forces, marking the second seizure of its kind this month.

The incident has sparked fury in Venezuela, with the country’s government describing the latest US action as “theft and kidnapping”.

“These acts will not go unpunished,” it warned.