A Pakistani delegation led by the country's powerful military chief travelled to Iran on Wednesday afternoon, hours after US President Donald Trump suggested a second round of peace talks could take place later this week.
The visit by Pakistani officials – who are leading international efforts to broker an end to the six-week regional conflict – is the latest sign of momentum towards a fresh round of direct Iran-US talks.
Iranian state media said that Field Marshal Asim Munir was leading the delegation to the country to deliver a message from the US and arrange a second meeting.
This comes hours after Trump suggested that US negotiators could return to Pakistan for talks "over the next two days" and praised Munir's "fantastic" diplomatic efforts.
Marathon peace talks in Islamabad over the weekend failed to find a breakthrough and resulted in the US announcing a blockade on Iranian ports , jeopardising the shaky two-week ceasefire that came into force on 8 April.
Pakistani officials are now racing to arrange fresh negotiations before truce ends next Wednesday and prevent a return to a conflict that has caused widespread destruction across the region and threatens to plunge the global economy into recession.
Trump's comments came amid rising speculation about a new round of negotiations after 21 hours of talks over the weekend failed to produce an agreement. US Vice President JD Vance said the negotiations had faltered over the nuclear issue, telling reporters in Islamabad that Tehran had not provided guarantees it would not build a bomb.
US news media reported that the disagreement centred on the suspension of nuclear enrichment, with the US delegation demanding a 20-year freeze and Tehran offering less than 10 years. It remains unclear whether the two sides reached an agreement over the future of Iran's stockpile of enriched material, which is believed to be buried inside a bombed-out nuclear facility in central Iran.
Leaks during the talks suggested that the future of the Strait of Hormuz was also a key sticking point, with Iran continuing to demand long-term control over the critical chokepoint. The Iranian Revolutionary Guards Corps (IRGC) quickly took over the strait after Israel and the US launched the war at the end of February, and has since charged fees on a small number of vessels leaving the Gulf waters.
Tehran's stranglehold over the strait has triggered outrage in the Gulf, which relies on the waterway for almost all its exports. Countries around the world have called on Tehran to respect freedom of navigation in the region. The UK and France will co-lead a meeting of more than 40 countries on Friday to discuss how to reopen the strait.
In a bid to raise the pressure on Tehran, the US began imposing a blockade on Iranian ports that would see only ships not linked to Iran exit the Strait of Hormuz. The US military said on Tuesday that no ships had left the region over the last 24 hours, with six vessels obeying US naval forces' command to return to an Iranian port on the Sea of Oman.
The blockade is likely to intensify the global energy crisis by removing Iranian oil from the market, in addition to the restrictions already imposed on Arab Gulf producers by Tehran.
The effective closure of the strait – which before the war carried a fifth of the world's oil and gas – has triggered energy shortages and surging fuel costs across the world.
It is also raising tensions with China – the biggest buyer of Iran's oil – which called the move "irresponsible and dangerous" and warned that it could undermine the fragile ceasefire.
The Iran-US talks coincide with a separate US-led initiative to end the conflict between Israel and Hezbollah, which saw senior Lebanese and Israeli diplomats hold their first face-to-face meeting in a generation on Tuesday.
Israel is demanding the Lebanese government forcibly disarm the Iran-backed group as a precondition to ending the war. It has refused to agree to any ceasefire until it confronts Hezbollah and vowed to continue its plans to occupy swathes of the country's south.
Hezbollah has refused to recognise the talks and said it would ignore any agreements struck by the Lebanese government.