Two months into the war that started with US-Israeli strikes on Iran, the vital sea channel remains closed, choking off a fifth of the world's supplies of oil and gas.
That has sent global energy prices surging and heightened concerns about the risks of an economic downturn.
Efforts to resolve the conflict have hit an impasse, which the US is trying to unlock with a naval blockade of Iran's oil exports, the country's economic lifeline.
With talks stalled, US President Donald Trump is slated to be briefed on Thursday on plans for a series of fresh military strikes on Iran in hopes it will return to negotiations, according to an Axios report.
That spurred big gains in oil prices, with the benchmark Brent crude contract topping $US125 a barrel at one point.
Since the start of 2026, Brent prices have more than doubled, rising on Thursday to their highest since March 2022, fuelling inflation and sending pump prices to politically painful levels worldwide.
Iran has pledged to continue disrupting traffic through the strait as long as it is threatened, which might mean more Middle East oil supply disruptions from a conflict that has killed thousands.
Tehran warned of "unprecedented military action" against continued US blockading of Iran-linked vessels.
Trump has said Iran cannot have a nuclear weapon, while Tehran says its nuclear ambitions are peaceful.
"They don't know how to sign a non-nuclear deal. They'd better get smart soon!" Trump said in a social media post on Wednesday, without explaining what such a deal would entail.
The post featured a mock-up image of him wielding a machine gun, captioned, "No more Mr Nice Guy."
With Washington and Tehran trading public threats, mediator Pakistan was trying to avoid escalation while the two sides exchange messages on a potential deal, a Pakistani source said on Wednesday.
The State Department cable said the US was inviting other countries to join a new coalition that would enable ships to navigate the Strait of Hormuz after traffic through the waterway stalled.
The proposed coalition, dubbed the "Maritime Freedom Construct", would share information, co-ordinate diplomatically and help enforce sanctions.
France, Britain and other countries have held talks on contributing to such a group but say they are willing to help open the strait only after hostilities cease.
Iran wants US acknowledgment of its right to enrich uranium for what it says are peaceful, civilian purposes.
It has a stockpile of about 440 kilograms of uranium enriched to 60 per cent, which could be used for nuclear weapons if further enriched.
Iran's parliament speaker and top negotiator, Mohammad Baqer Qalibaf, said on messaging app Telegram that Trump was trying to divide Iranians and force Iran to surrender through the blockade.
In a sign of the toll the war is taking on Iran's economy, its currency fell to a record low on Wednesday, and the central bank said inflation stood at 66 per cent for the month to April 20.
Iran's latest offer for resolving the war, suspended since April 8 under a ceasefire deal, would set aside discussion of its nuclear program until the conflict is formally ended and shipping issues resolved.
That did not meet Trump's demand to tackle the nuclear issue at the outset.
Tehran has largely blocked all shipping apart from its own from the Gulf through the Strait of Hormuz, since the US and Israel began air strikes on Iran on February 28.
The US began its blockade in April.
