However it’s feared that if the plan is accepted by the Prime Minister, it would lend a legitimacy to both rogue regimes. The Royal Navy frigate Montrose is already escorting British-flagged tankers and will be joined by the destroyer Duncan and support vessel Wave Knight today. France, Italy, Denmark, the Netherlands and Germany have now agreed to contribute, on condition that the effort is distinct from the US’ own operation, Sentinel, for fear of escalating tensions further.
And senior sources at the UK’s Permanent Joint Headquarters confirmed that plans to invite Japan, China and Russia to contribute have been sent to Downing Street.
One said: “If it helps ensure stability is resumed and maintained then it’s right that we extend the offer.”
The move was suggested after a summit on Thursday between military chiefs from the US, UK, Europe and the UAE in Florida, where US admirals failed to persuade Britain to join its Sentinel operation.
But James Rogers, of the Henry Jackson Society foreign policy think-tank, warned: “Inviting China and Russia would do nothing to increase stability in the region – the risk is that we are placing short-term interests before long-term ones.
“The irony of Beijing taking part in a ‘freedom of navigation’ exercise as it builds islands and hampers navigation in the South China Sea cannot be overestimated. This would also hasten its ambitions to increase its footprint in the region.
“Russia would benefit internationally from having a seat at a top table and would see this as an opportunity to work more closely with Germany, and deepen the wedge between Europe and the US.”
While the shape of the coalition is not yet known, one solution could be to use the Joint Expeditionary Force as a template, said its creator, former Armed Forces head General Lord Richards, last night.
Led by the UK, the coalition of nine European navies has just returned from an exercise in the Baltic and is in a state of high readiness. Its existing command-and-control structure could, sources say, be utilised for operations in the Gulf.
Lord Richards said: “If you want a quick, efficient and neat solution, you’d team up with the US. If, as seems the case, political reasons make this impossible, a European alternative is harder to put together in a sensible timeframe.
“This issue in the Gulf is exactly the sort of thing we were thinking of when we created the JEF. If I were chief of the defence staff today I’d be looking energetically at this option.”
Ex-Nato director Fabrice Pothier said: “Using the JEF as a framework would be a coup for Boris Johnson. It would show the UK really means it, and is capable of backing up its ambitions with military capability.”
Last night Whitehall sources confirmed that Theresa May “personally intervened” to reject a US offer of assistance following Iran’s seizure of the Stena Impero this month.
Mr Pothier added: “The UK’s continued loyalty to the dead parrot which is the Iran nuclear deal means it is fighting this issue with one hand tied behind its back.
“The other problem is Brexit and the negotiations to come over the next few weeks. There is a sense that the UK cannot afford to follow a
different path from Germany and France right now.”
He also cited Britain’s recent decision to send 250 troops to support the French-led mission in Mali – described by Lord Richards as “staggering and unthinkable in previous years.”
Mr Pothier added: “All this shows that, ironically, British foreign policy has never been more pro-EU. By targeting a British-flagged tanker, Iran has shown that it’s aware of this and is more than happy to drive a wedge between the UK and the US.”