France and Britain will chair a meeting on Friday of around 40 countries aimed at signalling to the United States that some of its closest allies are ready to play a role in restoring freedom of navigation in the Strait of Hormuz once conditions allow.
Iran has largely closed the strait to ships other than its own since the start of US-Israeli airstrikes against it on February 28. On Monday, Washington imposed a blockade on ships entering or leaving Iranian ports.
US President Donald Trump has called on other countries to help enforce the blockade and has criticised NATO allies for not doing so.
Britain, France and others say joining the blockade would amount to entering the war, but they have said they would be willing to help keep the strait open once there was a lasting ceasefire or the conflict ended.
The initiative being discussed does not, for now, include the United States or Iran, though European diplomats said any realistic mission would ultimately need to be coordinated with both.
Washington will be briefed on the outcome of the talks.
According to a note sent to invited nations, the aim of the meeting is to reaffirm full diplomatic support for unfettered freedom of navigation through the strait - through which around a fifth of the world's oil and liquefied natural gas usually passes - and the need to respect international law.
The meeting will also address economic challenges facing the shipping industry and the safety of more than 20,000 stranded seafarers and trapped commercial vessels.
It will also outline preparations for the deployment - when conditions are met - of a strictly defensive multinational military mission to ensure freedom of navigation.
A chair’s statement is expected at the end of the meeting to give a more tangible sense of what such a mission could entail, although it is not expected to spell out what specific countries might contribute.
Three European diplomats said that there could be an announcement on an operational centre, possibly based in Oman. Two of the diplomats said there were some differences on whether any future mission would need a new legal framework through a UN Security Council resolution.
The final statement should reiterate the opposition to any tolls on the Strait of Hormuz and a call to any state that would want to contribute, either with military assets to a future international naval mission or with diplomatic, political or possibly financial support, two of the diplomats said.
President Emmanuel Macron, deeply unpopular British Prime Minister Keir Starmer, German Chancellor Friedrich Merz and Italian Prime Minister Giorgia Meloni will attend the meeting in Paris, while officials from across Europe, Asia and the Middle East will join by video conference.
Merz said on Thursday that Germany was, in principle, ready to help secure transit routes after hostilities, but preferably with a UN mandate, suggesting he would prefer the United States to be involved.
China has been invited, although it was not clear whether it would take part.
Several diplomats said the mission might never materialise if the situation in the Strait of Hormuz returned to normal. Others said shipping companies and insurers could seek such a deployment during a transitional phase to provide reassurance.
"It can involve intelligence sharing, mine-clearance capabilities, military escorts, information procedures with neighbouring countries and more,” a senior French official briefing reporters said.
"The objective is clear, and the resources deployed will naturally depend on the situation." Britain said Friday's talks would feed directly into a multinational military planning meeting next week.
(Reporting by John Irish in Paris; Additional reporting by Sam Tabahriti in London; Editing by Alison Williams, Ingrid Melander and Alex Richardson)