Britain and France will on Tuesday host a virtual meeting of defence ministers from more than 40 countries to convert a diplomatic ceasefire into concrete military plans for reopening the Strait of Hormuz. The announcement, made by the British Ministry of Defence on Sunday, marks the first ministerial-level gathering of the multinational mission that London and Paris have been quietly assembling since April, when military planners met in London to thrash out the practicalities of protecting navigation through the world’s most strategically vital oil chokepoint.

The timing of the meeting reflects a fragile window of opportunity. A sustainable ceasefire between Iran and its Gulf adversaries has taken hold in recent weeks, allowing the two European powers to shift from diplomacy to operational planning. John Healey, the British Defence Secretary, who will co-chair the session alongside his French counterpart Catherine Vautrin, described the objective bluntly: “We are turning a diplomatic agreement into practical military plans to restore confidence in shipping through the Strait of Hormuz.” The mission is described as defensive in nature, focused on mine-clearing and escort operations, with Britain having already dispatched HMS Dragon to the region and France positioning its carrier strike group in the Red Sea.

From Tehran, the reaction has been predictably combative. Iran’s Deputy Foreign Minister Kazem Gharibabadi warned London and Paris on Sunday against sending warships into the strait, a thinly veiled threat that underscores the risks of any multinational deployment. Iranian state media has framed the European initiative as a provocation, despite the mission’s stated defensive posture. Analysts in London note that Iran’s opposition is less about the size of the naval force than about the precedent it sets: a permanent multinational security architecture in waters Tehran has long treated as its own strategic preserve.

Viewed from Washington, the European-led effort is a welcome but cautious development. The Trump administration has labelled Iran’s response to a separate US peace proposal “totally unacceptable”, a diplomatic rift that complicates any coordinated approach. Gulf Arab states, meanwhile, watch with mixed feelings. Drone attacks have already tested the ceasefire, with an incendiary drone striking a ship off Qatar, a reminder that even a temporary truce remains brittle. For the smaller Gulf monarchies, the prospect of European naval protection offers a hedge against both Iranian aggression and over-reliance on American security guarantees.

Looking ahead, Tuesday’s meeting will need to resolve several contentious questions: how many ships each participating nation will contribute, who commands the force, and — most critically — what rules of engagement will govern encounters with Iranian patrols. The British-French plan is predicated on the ceasefire holding, but any escalation, whether a new drone strike or a naval confrontation, could collapse the entire edifice. What begins as a defensive mission may evolve into a longer-term naval presence, reshaping the security balance of a waterway through which a fifth of the world’s oil passes. The success of this gathering will be measured not in communiqués, but in whether the strait remains open to the world’s tankers.