British Actions

On 14th June 2026 Royal Marine Commandos commandeered a ship named Smyrtos that was sailing under the flag of Cameroon.  The Ministry of Defence admitted that the ship was boarded in international waters as it was more than 12 nautical miles from the UK coast (see: https://www.bbc.co.uk/news/articles/clyek039l2vo ).  Despite this, the MoD claimed that the operation “was in full compliance with both domestic and international law”.  This claim was simply asserted without citing any aspect of International Law which would justify the claim. 

In March 2026, Keir Starmer announced that British armed forces were “now able to board sanctioned vessels that are passing through our waters”.  However, it was always the case that vessels passing through British waters were subject to boarding by British armed forces and the fanfare surrounding that statement did not announce anything new.  The issue raised by the recent actions is directly related to what, under international law, constitutes British waters. While what Starmer claims would be true  in the context of British territorial waters, i.e, up to twelve miles off the British coast, it is not the case that the same rights apply to the British armed forces when it comes to boarding vessels beyond the twelve-mile limit, even if those waters are deemed to be part of Britain’s Exclusive Economic Zone (EEZ). 

The suspicion must be that the theatre surrounding Starmer’s announcement in March was designed to convey the impression to the public that a new situation had emerged which somehow transcended the existing distinction between British rights over its territorial waters and the waters of its Exclusive Economic Zone.

A country has a right to sanction vessels for any reason—though one would hope that the reasons given would comply with the country’s domestic laws.  So far the UK has sanctioned over 500 vessels it accuses of carrying Russian oil.  This has been done under British domestic law.  The effect of these sanctions means that such vessels are banned from entering UK ports and British firms or individuals are prohibited from offering financial, insurance, or brokerage services to such vessels.  It also means that such vessels sailing through British territorial waters run the risk of being intercepted, boarded and taken into a British port. 

But that is the limit of the powers allocated to the British armed forces when it comes to sanctioned vessels under its domestic law.   There is no right to board or commandeer such vessels if those vessels are in international waters, and no domestic court can claim that extra-territorial right—at least in peace time:  and Britain has not yet declared de jure war on Russia, despite acting de facto in this regard!

There are exceptions which would permit Britain to undertake such actions in international waters, but they are specifically defined under international law. 

Actions taken in international waters—like those taken by the French Navy earlier in the year and now by the Royal Marines—are only justified if conducted under the principles stipulated by the United Nations Convention on the Law of the Sea (UNCLOS).   

Actions involving the commandeering or seizure of a vessel in international waters are considered acts of piracy if they do not come under the exceptions stipulated under UNCLOS. 

Those exceptions are:

That a warship has the right to board a foreign merchant ship if there is reasonable ground to suspect it is engaged in piracy, human trafficking, illegal broadcasting, or sailing without nationality.

The naval vessels of a state may also seize or commandeer a foreign merchant ship if it has reasonable grounds to believe that the ship has infringed the state’s laws while in its territorial waters or Exclusive Economic Zone.  However, when it comes to infringements in the Exclusive Economic Zone, such infringements are generally related to the illegal exploitation of the sea resources of a country that come within its 200 nautical mile Exclusive Economic Zone, such as illegal fishing.

Also, a state can take proportionate action, including boarding, seizing and commandeering merchant vessels of a foreign country if it is deemed to pose an immediate military or security threat.

The other broader justification for a state to intercept, board and seize a merchant ship of a foreign Power in international waters is if mandated by a UN Security Council Resolution which requires the enforcement of international sanctions or embargo as instructed by the Security Council. 

In the case of the transportation of Russian oil by sanctioned ships, the boarding and seizing of such vessels in international waters is not endorsed by a UN Security Council Resolution—as obviously Russia would use its veto powers if such a resolution was ever proposed. 

When the question is posed:  

“How can it be legal under international law for the UK to capture the captain of a ship in international waters for contravening UK sanctions that are not endorsed by the UN or any other body that upholds the law of the sea?”, 

the Google response is:

“The UK asserts the legality of these actions under international law primarily by targeting vessels classified as stateless or operating under flags of convenience.  Under the United Nations Conventions On The Law of the Sea (UNCLOS), ships without valid registration, or that misuse flags, forfeit their immunity from foreign interference.

This provides a mechanism for UK forces to board and detain these vessels:

“Stateless Status:  Many vessels in the ‘shadow fleet’ evade regulations by turning off tracking transponders and frequently changing or dropping their flag.  Under UNCLOS Article 110, warships encountering a stateless vessel on the high seas have the right to board and verify credentials.”

“Domestic Jurisdiction within Territorial Waters:  Under UNCLOS, states can enforce domestic laws within their territorial seas (the 12 nautical mile zone).  

“The  UK government authorised its military and law enforcement (like the National Crime Agency) to board and detain ships in UK waters for violating domestic shipping and trade sanctions.”

“The “Right of Visit”:   Even when interdictions begin slightly outside territorial limits, the UK utilises the legal doctrine of statelessness to justify these physical interdictions.  Once the vessel is detained, the captain can be arrested and criminally prosecuted by domestic courts for contravening UK regulations (e.g., the Sanctions and Anti-Money Laundering Act).”

The problem with this answer is that the British practice is arbitrary when it comes to designating a ship as “stateless or operating under flags of convenience”.   The fact is that many ships operate under “flags of convenience”.   In fact according to Wikipedia:

“The vast majority of the world’s merchant ships operate under flags of convenience.  Over 70% of the global fleet’s total tonnage—including most container vessels, cruise ships, and tankers—is registered in “open registries” outside the actual home country of the ship’s owners”…”

As for the concept of “stateless ships”, this appears to be a charge that depends on those doing the charging!  Again, according to the Google answer to my question, “How is a ship designated stateless?”, the answer was:

“A ship is designated “stateless” under international law when it lacks a valid national registration or is not legally entitled to flag the flag of any state.  Because ships are governed by the laws of their “Flag State”, stateless vessels effectively forfeit the protection of the high seas and become subject to international jurisdiction…”

In the case of the ship commandeered by the Royal Marines in the Channel, there has been an accusation that it is “stateless” because it has changed its flags on a number of occasions.  But that is not unusual, and there has been no accusation that it is not entitled to do this.

Even the Google answer describing the excuse that the British have used for its act of piracy acknowledges that:

“These actions are highly contested legally.  Critics argue this expands the concept of statelessness to circumvent the lack of globally endorsed, UN-backed sanctions at sea.”

It is obvious that British and French actions in commandeering foreign ships transporting Russian oil through international waters can not be justified by any reasonable reading of the UN Convention of the Law of the Sea. 

Because of this, there is a strong likelihood that the latest ship to fall foul of such illegal action will eventually be freed, as otherwise an international dispute mechanism under the International Tribunal for the Law of the Sea (ITLOS) could be initiated and leave the British Government having to justify its actions in more precise terms than the vague assertions that it currently relies upon in its public statements. 

Eamon Dyas

Post-Script:  Compounding The Provocation!

Since the above was written, there have been reports that Britain might auction the oil cargo of the Smyrtos—the ship commandeered by the Royal Marines on 14th June  (See: https://splash247.com/seized-tanker-tests-the-limits-of-shadow-fleet-enforcement/).

I’m not sure how this could be done legally within existing rules.  Seized cargoes and vessels can be treated as “prize” in wartime conditions—but not when a country is not at war! However, over the past four years, Britain—along with NATO and the EU—have been stretching the existing Rules of the Sea to the point of destruction in their desperate attempts to damage Russian trade in energy by interdicting the carriage of that energy first by pipeline and, for the past two years, by sea. 

When it comes to Russia’s sea-borne trade, we have seen this done by implementing ‘sanctions’ against Russian oil and LNG.  And these are operated when vessels pass through the national waters of sanctioning states.  However, the challenge has always been how to make such sanctions effective when it came to the transit of these commodities through international waters, or when it came to international transit rights through straits.  

Interception in those circumstances on the basis of sanctions that did not have the authority of the UN would be considered illegal. 

And so, as part of the construction of a case for creating a legally enforceable action for what in other circumstances would be illegal, we saw the invention of the concept of the “Russian Shadow Fleet”!  This fleet was initially claimed to consist of old tankers whose rusting hulks represented an ecological danger and, by implication, open to interception as a means of protecting the sea environment from oil spillage. 

Then there was the claim that these ships were sailing without recognised insurance, and therefore unable to muster the funds to compensate victims in the event of an accident at sea.  After that it was asserted that the tankers were sailing under false flags and therefore at sea illegally. 

All or any of these designations meant that, if the allegations were true, the national navies of Britain and the EU could legally intercept any vessel, even if it was outside the territorial waters of the navy concerned.  The problem lay in proving those designations.  And for years this has been the constraining issue for the UK and EU. 

Those designations raised many problems:

Firstly, claiming that the age of a ship automatically made it unseaworthy was something that was not necessarily intrinsically true.  It depended on how regularly the vessel was overhauled and how long it was at sea during its lifetime.  Because of this, such a claim of unseaworthiness would need to be proven in a domestic court by a physical examination of the ship:  and that required it to be impounded in a port of the intercepting navy.  All of this was considered too far a stretch for the UK and EU, as such action ran the danger of the actual physical condition of the ship disproving the charge of unseaworthiness:  and so this excuse for interception was not used. 

Secondly, the claim that the “Shadow Fleet” consisted of uninsured vessels was also spurious.  This was based on the assumption that a ship not insured by the companies of the City of London or some other Western-recognised company made that ship open to international seizure.  Again this proved to be a legal blind alley for the UK and EU, given the fact that the Russian Government underwrote the insurance of these vessels—something that made that excuse for interception untenable.

Thirdly, the claim that these ships were sailing under false flags of convenience was something that also required proof.  However, it seems that this claim was also until recently something that neither the UK or EU felt confident in forming a case for interception around. 

Then last March Starmer issued his statement announcing that British armed forces were “now able to board sanctioned vessels that are passing through our waters”,  which left everyone at the time wondering what this meant as surely it had always been the case that British armed forces could do so when it came to Britain’s territorial waters.  

Subsequent events, with the boarding of the Smyrtos on 14th June by the Royal Marines (complete with camera crew), revealed the intent of this statement.  It referred not to the boarding of ships in transit through British territorial waters but in fact to the boarding of a cargo ship in transit through the Straits of Dover—which are in effect international waters due to the rights of transit designated in the UN Convention on the Law of the Sea!

Since then it has emerged that the legal basis on which the UK hung its action against the Smyrtos was that the ship was “stateless”, and therefore subject to interception in international waters. 

This assertion was based on the claim that it was sailing without being included on any state’s shipping register.  

However, the Smyrtos had been registered under the flag of the Cameroons since December 2025, and had sailed as such on several occasions since then.  This was confirmed by the tracking website Marine Traffic in the BBC’s own report on the seizure of the ship on 14th June (see earlier link).  Indeed the Marine Traffic website implies that at the time the ship was commandeered it was still registered under the Cameroon registry and that it is likely to have been registered as such at the time it left the port of Ust-Luga near St. Petersburg ten days earlier.  But, by March 2026, it seems it had been, or was in the process of being, de-registered from the Cameroon shipping register! 

So, by June this year the UK felt confident enough to intercept and commandeer the vessel in international waters based on the charge that the ship was “stateless”!

It has now emerged that, in order to circumvent the legal obstacles to the UK and EU intercepting vessels carrying Russian oil, extreme pressure has been put on Cameroon to de-register ships that the UK and EU has designated as being part of the Russian “Shadow Fleet”!

In the context of that pressure, is it a coincidence that Cameroon was designated a joint colony of Britain and France after the First World War:  and that these are the only countries that have intercepted vessels carrying Russian cargoes in international waters;  and that Cameroon remains economically heavily dependent upon France to this day.  France is the country’s second most important trading partner! 

These factors leave the country highly susceptible to pressure designed to help the UK and EU construct their legal case for intercepting vessels carrying Russian commodities over international waters.

Eamon Dyas