Russia has dispatched naval assets to escort a “shadow fleet” oil tanker being pursued by the US across the Atlantic, according to reports, as tensions over the vessel escalate.

The ship, formerly known as the Bella 1, has spent more than two weeks attempting to evade a US blockade of sanctions-hit oil tankers operating near Venezuela. Ship-tracking data from MarineTraffic showed the vessel nearing Iceland’s exclusive economic zone on Wednesday.

The ship began its journey in Iran and was bound for Venezuela to pick up oil, part of the so-called shadow fleet that moves oil for Russia, Iran and Venezuela despite US and allied sanctions.

According to the Wall Street Journal, Russia on Wednesday dispatched a submarine and other naval vessels to escort the tanker, which is believed to be heading for Murmansk in northern Russia. It remains unclear where the Russian navy could rendezvous with the ship, but the oil tanker’s entry into European waters has coincided with the arrival of about 10 US military transport aircraft and several helicopters in the UK.

In December, the vessel’s crew repelled an attempted US boarding near Venezuelan waters before abruptly changing course and heading into the Atlantic.

The tanker was renamed Marinera, with its crew hastily painting a Russian flag on the hull, and it was added to an official Russian shipping registry. Moscow subsequently lodged a formal diplomatic protest demanding that Washington halt its pursuit.

The ship has been under sanctions by the US treasury since July 2024, accused by American authorities of being involved in carrying illicit cargo for a company owned by Hezbollah, the Iranian-backed Lebanese group.

Russia’s state-run outlet RT earlier posted a video it said was filmed from the deck of the oil tanker, showing a US Coast Guard vessel trailing it. On Tuesday, Russia’s foreign ministry said it was monitoring the situation “with concern”.

On Tuesday, the US military’s Southern Command said it was prepared to support other US government agencies in countering sanctions-hit vessels operating in the region, stressing that American naval forces were closely monitoring ships of interest.

Flight records show the Marinera appears to have been closely monitored over the last two days by US P-8 surveillance aircraft flying from RAF Mildenhall in Suffolk as it crossed the Atlantic. Any US military operation launched from the UK would be expected to involve prior coordination with British authorities.

In November, the tanker departed the Gulf of Oman, transiting the Suez canal and the strait of Gibraltar before crossing the Atlantic in early December. As US pressure on Venezuela intensified – later culminating in the capture of the country’s president, Nicolás Maduro – the vessel stopped abruptly near the Caribbean on 15 December and reversed course, heading back towards Europe.

Its return journey across the Atlantic has been markedly atypical, according to marine transport experts. Instead of taking the usual route through the Channel, the tanker veered sharply north, steering into the stretch of ocean between Iceland and Ireland.

Registry data reviewed by the New York Times showed that at least three other oil tankers that have operated in Venezuelan waters in recent weeks had since been reflagged under the Russian banner, pointing to a growing trend of Moscow extending its registry to vessels facing US sanctions.

The latest standoff comes amid faltering US efforts to pressure Moscow to end its war in Ukraine. Donald Trump said on Saturday that he was frustrated with Vladimir Putin over Russia’s continued fighting. “I’m not thrilled with Putin. He’s killing too many people,” Trump said.

The US president rejected Moscow’s claims that Ukraine had tried to strike Putin’s residence in order to sabotage the ongoing peace talks.