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At least 25 sanctioned Russian ships pass through UK waters after boarding threat

Published by Global Banking & Finance Review

Posted on March 31, 2026

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· Last updated: April 1, 2026

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At least 25 sanctioned Russian ships pass through UK waters after boarding threat
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By Andrew MacAskill and Muvija M LONDON, March 31 (Reuters) - More than two dozen ships sanctioned for being part of Russia's so-called shadow fleet have passed through UK waters since Prime Minister

Sanctioned Russian Ships Continue UK Channel Passage Despite Boarding Threat

Continued Passage of Sanctioned Russian Vessels Through UK Waters

By Andrew MacAskill and Muvija M

LONDON, March 31 (Reuters) - More than two dozen ships sanctioned for being part of Russia's so-called shadow fleet have passed through UK waters since Prime Minister Keir Starmer last week authorised the military to detain vessels used by Moscow to export oil.

The figures based on ship tracking data analysed by Reuters show that oil tankers sanctioned by Britain are continuing to travel along England's southern coast in the same numbers as before the announcement.

British officials said almost a week ago that the military was ​preparing to board the vessels for breaches of sanctions and the government hoped the announcement would force the ships to take longer routes away from British waters. Russia called it a "deeply hostile move" and said it could retaliate.

Since that statement, the British military has not announced it has boarded any Russian vessels while at least 25 sanctioned ships have entered British waters when travelling through the Channel as before, according to the Reuters analysis.

Government and Military Response

Starmer's Position and Deterrence Strategy

STARMER SAYS RUSSIA COULD PROFIT FROM OIL PRICE RISE

James Fennell, a former British naval officer, said the British military would probably target Russian vessels only selectively, citing the complexity of an operation, the threat of legal challenges and the risk that such action could bring Britain "one step closer to war with Russia".

"The government is hoping the threat acts as a deterrent and will gauge the effect before sanctioning a potentially risky boarding operation," he said. "They will be using back channels to tell Russia to cease and desist."

Britain's Ministry of Defence said any enforcement action would be "considered on a case-by-case basis" and it would not provide "a running commentary" on potential action.

Starmer said last Wednesday evening he had authorised the boarding and detention of Russian vessels to prevent Russian President Vladimir Putin from making "dirty profits" from the sharp rise in oil prices driven ​by the U.S.-Israeli war with Iran.

Strategic Importance of the Channel

Russian ships in the so-called shadow fleet of tankers used by Moscow to fund its four-year war against Ukraine sail through the Channel as it is the most convenient route for travelling between the Baltic and southern Europe and beyond.

Other European nations, including France, Belgium and Sweden, have in recent months boarded and detained vessels to disrupt the network of ships.

Trump this month temporarily eased sanctions on Russian oil as part of his administration's attempt to tame energy prices.

Legal and Enforcement Challenges

Sanctions and Enforcement Data

'VERY LIMITED' LEGAL GROUND TO BOARD SHIPS

Britain has placed sanctions on 544 Russian shadow fleet vessels, meaning they are prohibited from entering British ports and can be detained, according to the government.

Pole Star Global, a maritime data and intelligence company, said about two dozen of these ships travelled through British waters a week on average since the start of the year.

Legal Basis for Boarding

International Law and UK Sanctions

Douglas Guilfoyle, a professor who specialises in maritime security at the University of New South Wales, said even though Britain had sanctions on Russian vessels it would need to rely on untested legal arguments to board the ships.

Guilfoyle said that there were only two clear legal bases to detain the vessels: a U.N. Security Council sanctions regime - not in place at present - or treating seizures as a "countermeasure" in response to Russia's war in Ukraine, which he described as a "novel and untested" legal argument.

"There are very limited exceptions that would justify interference with the right of transit passage or the right of innocent passage by a foreign vessel – even one subject to UK autonomous sanctions," he said.

Perceptions of Government Resolve

Brett Erickson, a sanctions expert who works at the consulting firm Obsidian Risk ​Advisors, said the British government looked weak because it announced it was ready to detain Russian vessels, but had yet to take any action.

"With sanctions you can't be half in, you either have to be all in, or all out," he said.

(Editing by Alison Williams)

Key Takeaways

  • Despite PM Starmer authorising military boarding of sanctioned Russian oil tankers, over two dozen vessels have passed through UK waters since, signaling limited immediate deterrence.
  • Legal hurdles remain: experts note the UK lacks clear legal authority absent UN sanctions or new countermeasure frameworks, making boarding operations complex and risky.
  • Broader context: the global shadow fleet has swelled, with thousands of vessels bypassing sanctions—UK has sanctioned hundreds, but enforcement in coastal waters remains selective and cautious.

References

Frequently Asked Questions

How many sanctioned Russian ships have passed through UK waters recently?
At least 25 sanctioned Russian vessels have passed through UK waters since the British government's recent threat to board such ships.
What prompted the UK to threaten boarding of Russian vessels?
The UK authorized military action to deter Russia from profiting from rising oil prices caused by global conflicts, specifically targeting ships used for oil exports.
Has the British military actually boarded any Russian vessels so far?
As of the article's publication, the British military has not carried out any publicized boardings of Russian vessels.
What legal challenges are involved in boarding sanctioned Russian ships?
Legal experts say boarding requires novel and untested legal arguments, and there are limited exceptions in international law to interfere with transit or innocent passage.
How have other European countries responded to Russian shadow fleet vessels?
Countries like France, Belgium, and Sweden have boarded and detained Russian vessels to disrupt the shadow fleet network.

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