Sir Keir Starmer has described the reopening of the Strait of Hormuz as a “global responsibility” as he co-hosts a gathering of world leaders in Paris. The crucial shipping lane, vital for a fifth of global oil supplies, was closed by Iran following strikes by the United States and Israel.
In retaliation, US President Donald Trump has begun blockading Iran’s oil ports, aiming to stem Tehran’s fossil fuel income. The Prime Minister is expected to tell the summit that unconditional and immediate reopening of the strait is a global responsibility, and that action is needed to get global energy and trade flowing freely again.
Alongside French President Emmanuel Macron, Starmer will outline a commitment to establish a multinational initiative to protect freedom of navigation. The call will focus on supporting the US-Iranian ceasefire and developing a plan to ensure the strait remains open to shipping after the Middle East war ends.
Around 40 countries and the International Maritime Organisation are expected to participate. Planning for a joint defensive mission is under way, with a view to countries sending a combined military effort as soon as conditions allow, Downing Street has said.
Foreign Secretary Yvette Cooper and Chief of the Defence Staff Sir Richard Knighton will join the Prime Minister. The conference will be followed by a multinational military planning summit at the Permanent Joint Headquarters in Northwood, north-west London, next week.
Cooper is on her own diplomatic offensive in the run-up to the US-Iran ceasefire expiring on Tuesday and is due to visit Turkey, the Gulf, and Japan.



