Donald Trump said the US would launch a naval blockade of the Strait of Hormuz after Washington and Tehran failed to reach an agreement during talks in Islamabad.
Iran failed to give an “affirmative commitment” that it would refrain from seeking a nuclear weapon, US vice-president JD Vance said.
Iran’s top negotiator said it was up to Washington to earn the Islamic republic’s trust.
Analysts warned the breakdown of talks and Trump’s plan for a naval blockade of the strait would push up oil prices.
The UK would not be involved in a blockade, according to people familiar with the matter, after Trump said Nato members “want to help with the strait”.
The situation in the strategic waterway would remain “unchanged” unless the US agreed to what Iran considered to be a “reasonable” deal, according to Iranian media reports.
The direct talks were the first between the two enemy states, which have never had diplomatic relations, in more than four decades.
