Donald Trump’s blockade of the Strait of Hormuz has come into effect after the US and Iran failed to reach an agreement during peace talks.
The US military has vowed to prevent ships from accessing Iranian ports from Monday onwards.
The key oil and gas shipping lane has been throttled by Iran in retaliation for the US-Israel war against it, sending energy prices soaring.
Shortly after the blockade came into force, President Trump said on Truth Social: “Iran’s Navy is laying at the bottom of the sea, completely obliterated - 158 ships. What we have not hit are their small number of, what they call, ‘fast attack ships,’ because we did not consider them much of a threat.
“Warning: If any of these ships come anywhere close to our BLOCKADE, they will be immediately ELIMINATED, using the same system of kill that we use against the drug dealers on boats at Sea. It is quick and brutal. P.S. 98.2% of Drugs coming into the U.S. by Ocean or Sea have STOPPED! Thank you for your attention to this matter. President DJT.”
Earlier, Sir Keir Starmer refused to back the move.
Speaking on Monday morning, the Prime Minister said “we are not supporting the blockade” as he repeated calls to fully reopen the strait, following the failure of face-to-face negotiations between the US and Iran at the weekend.
Speaking to BBC Radio 5 Live, Sir Keir said: “What we've been doing over the last few weeks - and this was part of what I was discussing with the Gulf states last week - is bringing countries together to keep the strait open, not shut.”
He said: “We're not supporting the blockade and all of the marshalling diplomatically, politically and capability - we do have mine-sweeping capability, I won't go into operational matters, but we do have that capability - that's all focused, from our point of view, on getting the strait fully open.”
Trump lambasted Iran for failing to release its grip on the strait and commit to giving up its nuclear ambitions.
He wrote on his Truth Social platform that the US military would start “blockading any and all ships trying to enter, or leave, the Strait of Hormuz”.
He said the US navy would also “seek and interdict every vessel in International Waters that has paid a toll to Iran. No one who pays an illegal toll will have safe passage on the high seas”.
Trump added, without elaborating: “Other Countries will be involved with this Blockade.”
The US Central Command later said the US blockade, starting at 10am ET on Monday (3pm BST), would be “enforced impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including all Iranian ports on the Arabian Gulf and Gulf of Oman”.
The US military said it will “not impede” vessels transiting the Strait of Hormuz travelling to or from other countries.
After Trump's initial remarks on Sunday, Iran's Islamic Revolutionary Guards warned that military vessels approaching the strait will be considered a ceasefire breach and dealt with harshly and decisively, underlining the risk of a dangerous escalation.
Early on Monday morning, Trump posted on Truth Social that the US would blockade ships “entering or exiting” Iranian ports at 10am ET.
Trump has also said he is “fine” if Iran doesn't return to negotiations, a day after peace talks between the US and Iran in Pakistan failed to produce an agreement.
“I don't care if they come back or not. If they don't come back, I'm fine,” he told reporter on Sunday night.
Oil prices have jumped above $100 a barrel as energy markets reopened following the collapse of the talks and Trump’s blockade threat.
The UK Prime Minister has previously said “as many partners as possible” must be involved in coming up with a “viable plan” to reopen the maritime pinch point, pointing to the UK’s role in hosting talks on the issue with a coalition of countries.
The third such meeting convened by Britain is set to take place this week, following a virtual meeting of more than 40 nations chaired by the Foreign Secretary and a gathering of allied military officers.
Discussions included looking at issues such as clearing mines that have possibly been laid by Tehran to sink ships in the sea passage.
Trump told Fox News “the UK and a couple of other countries are sending mine sweepers” to the strait, and “it won’t take long to clean it out”.
The Prime Minister previously said UK mine hunting systems were already in the region. But this is thought to refer to minesweeping drones which could be deployed once the situation stabilises, and distinct from Mr Trump’s blockade.
Sir Keir – who faced fresh personal criticism from the US president – earlier on Sunday urged the US and Iran “to find a way through” after their 21-hour negotiations in Islamabad collapsed, casting uncertainty over the shaky two-week truce.
In a readout of the Prime Minister’s call with the Sultan of Oman, His Majesty Sultan Haitham bin Tarik al Said, a Downing Street spokeswoman said: “They discussed the peace talks held in Pakistan over the weekend and urged both sides to find a way through.
“It was vital there was a continuation of the ceasefire, and that all parties avoided any further escalation, the leaders agreed.”
Trump meanwhile continued to pour scorn on Nato and the UK over their refusal to support offensive operations against Iran, calling the defensive alliance “shameful”.
The Republican leader again compared Sir Keir to Neville Chamberlain, whose premiership was defined by his 1930s appeasement of Nazi Germany.
Trump told Fox News: “He made a public statement that ‘we will send equipment after the war is over’, that’s a Neville Chamberlain statement.”
The president said talks in Pakistan involving US vice-president JD Vance “went well, most points were agreed to, but the only point that really mattered, nuclear, was not”.
