The United States has announced it will impose a naval blockade on the Strait of Hormuz — the narrow waterway between the Persian Gulf and the Arabian Sea through which roughly a fifth of the world's oil passes — after high-stakes talks with Iran in Pakistan collapsed over the weekend without a deal. US Central Command said the blockade of all maritime traffic entering and exiting Iranian ports would begin on April 13 at 10 a.m. Eastern Time, following President Donald Trump's public declaration that the US Navy would enforce the measure. Trump also threatened to destroy Iran's energy infrastructure if no agreement is reached, and advisers are weighing the option of resuming limited military strikes to break the diplomatic deadlock, according to people familiar with the situation.

The breakdown came after a marathon negotiating session in Islamabad that saw both sides deploy unusually large delegations — Iran sending two planeloads of officials, and the US dispatching not only Vice President JD Vance but nearly 300 other officials. Vance reportedly spoke with Trump at least a dozen times during the talks and once with Israeli Prime Minister Benjamin Netanyahu. Despite the effort, the two sides could not bridge deep differences over Iran's nuclear programme, future control of the Strait of Hormuz, and questions of US compensation for prior military action. As one veteran Iran negotiator observed, twenty-one hours was simultaneously too many hours if the goal was merely to restate demands already rejected by Tehran, and far too few to settle a dispute two decades in the making.

Iran's response was defiant. Mohammad Baqer Qalibaf, the country's parliamentary speaker who led Tehran's negotiating team, said the talks had produced genuine progress on goodwill measures before Trump's threats derailed them.