U.S. President Donald Trump and British Prime Minister Keir Starmer hold a press conference after meeting at Checkers, near Aylesbury, England, on September 18, 2025.
Kevin Lamarque | Reuters
Prime Minister Keir Starmer said on Monday that Britain “does not support” the US blockade of Iranian ports and insisted the country would not be “drawn into” a war with Iran.
The move comes as President Emmanuel Macron confirmed that France and Britain will co-host a conference in the coming days aimed at restoring freedom of navigation in the Strait of Hormuz.
Macron did not explicitly rule out French involvement in the US blockade, but said the planned meeting would create a “peaceful multinational” and “strictly guarded” mission separate from the belligerents.
Britain’s Starmer told BBC Radio 5 Live on Monday: “We are not in favor of a blockade. Diplomatically, politically, Marshall-wise, we have the mine-sweeping capability. I won’t go into operational issues, but we have that capability. From our perspective, it’s all focused on completely opening the Channel.”
“What we’ve been working on over the past few weeks, and that was part of what we talked about with the Gulf states last week, is to bring countries together to keep the straits open rather than closed.”
Starmer’s comments came after US President Donald Trump signaled that other countries would help implement a US blockade of ships entering and exiting Iranian ports from 10am ET on Monday.
The move was announced after talks between the US and Iranian governments over the weekend failed to reach an agreement to end the conflict in the Middle East.
“The blockade will go into effect tomorrow at 10 o’clock,” President Trump told reporters on Sunday, adding that “other countries are working to prevent Iran from selling oil.”
He did not say which other countries would help. However, CNBC asked governments in Europe and the Middle East for further comment and clarification on whether they intend to assist the United States.
Both Europe and the Gulf have so far been reluctant to get involved in the conflict, wary of escalating the conflict, viewing it as a “war of choice” by the United States rather than necessity.
Germany has also said it will not join the blockade, and a government official told CNBC on Monday that Trump’s comments were “vague statements not based on new facts.”
Berlin has repeatedly denied military involvement in the Iran war, and the government reiterated that position on Monday, saying: “In recent days, the federal government has commented several times on the possibility of participation and its conditions. These statements remain valid.”
Side initiatives
In a post on X, French President Emmanuel Macron said he would host a meeting “together with the UK and other countries willing to participate” for a “peaceful multinational mission aimed at restoring freedom of navigation in the Channel.”
He added: “This strictly defensive mission will be carried out separately from the belligerent parties and will be deployed as soon as conditions permit.”
Mr Starmer said the British public was affected by the Iran war and had rising energy costs and did not want to “pay the price” for the conflict. Asked whether Trump was personally responsible for the impact on Britain’s energy bills, Starmer said it was Iran that was restricting navigation through the Strait of Hormuz.
The Prime Minister said: “We, the UK, have been very clear that we do not want to be involved in this war, and we have not been involved in it, but we have been involved in defensive actions as well.”
