The United States is pressing ahead with plans for an international coalition to open the Strait of Hormuz, according to a State Department cable, as oil prices surge on fears of lengthy disruptions to global fuel supplies.

Two months into the war that started with US-Israeli strikes on Iran, the vital sea channel remains closed, choking off 20% 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, with a ceasefire in place since April 8 but Iran still blocking the strait in response to a US naval blockade of Iran's oil exports, the country's economic lifeline.

US President Donald Trump is slated to receive a briefing on Thursday on plans for a series of fresh military strikes on Iran in hopes of making Iran more flexible on nuclear issues in negotiations, Axios news site reported late on Wednesday.

That spurred big gains in oil prices, with the benchmark Brent crude contract hitting more than $126 a barrel at one point, its highest level since March 2022.

Brent prices have doubled since the US-Israeli attack on Iran began on February 28, fueling inflation and sending pump prices to politically painful levels worldwide.

'Biggest energy security crisis in history' – IEA chief

On Thursday, International Energy Agency head Fatih Birol reaffirmed that the Iran conflict has caused the biggest energy crisis in history.

"The oil markets and gas markets are going through big difficulties," said Birol, at a conference in Paris. "Our world is facing a major economic and energy challenge."

Iran's new Supreme Leader Mojtaba Khamenei said in a published written message on Thursday that a new chapter for the Gulf and Strait of Hormuz has been taking shape since the conflict with the United States and Israel broke out on February 28.

Ahead of that, Tehran warned on Wednesday of "unprecedented military action" against continued US blockading of Iran-linked vessels, which, together with the possibility of further US military strikes, signaled there could be more Middle East oil supply disruptions from a conflict that has killed thousands.

Another plan to be shared with Trump involves taking over part of the Strait of Hormuz to reopen it to commercial shipping, the Axios report added, saying such an operation may involve ground forces.

US reiterates call for help in Strait of Hormuz 

In a sign the US was also envisaging a scenario where hostilities cease, the State Department cable invited partner countries to ‌join a new coalition called Maritime Freedom Construct (MFC) to enable ​ships to navigate the strait.

"The MFC constitutes a critical first step in the establishment of a post-conflict maritime security architecture for the Middle East," said the cable, which was due to be delivered orally to partner nations by May 1.

France, Britain and other countries have held talks on contributing to such a coalition but said they were only willing to help open the Strait when the conflict ends.

Lithuania's President Gitanas Nauseda said on Thursday he was supportive of his country joining the US freedom of navigation mission in the Strait of Hormuz, adding that he would present the proposal to the Baltic state's defense council.

"We have received the US proposal to join the Hormuz Strait navigation restoration coalition, and I intend to shortly present this proposal to the State Defense Council," the president told a news conference in Vilnius on Thursday. 

"We would need a mandate from parliament," he added.

Mediator Pakistan seeks to avoid escalation 

Mediator Pakistan was trying to avoid escalation while the two sides exchange messages on a potential deal, a Pakistani source said on Wednesday. Trump has said Iran cannot have a nuclear weapon, while Tehran says its nuclear ambitions are peaceful.

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.

The Pakistani source said the United States had shared "observations" on the Iranian proposal and it was now up to Iran to respond. "(The) Iranians asked for time till the end of the week," the source told Reuters.

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 kg of uranium enriched to 60%, which could be used for several nuclear weapons if further enriched.

Conflict has cost $25bn so far 

The war has cost the US military $25 billion so far, a senior Pentagon official said on Wednesday, providing the first official estimate of the price tag for the conflict.

In Iran, the currency fell to a record low on Wednesday, and inflation stood at 65.8% for the month to April 20.

Iran has executed at least 21 people since the start of the war and arrested more than 4,000 on charges related to national security, UN human rights chief Volker Turk said on Wednesday.

Iran's parliament speaker and top negotiator, Mohammad Baqer Qalibaf, said on Wednesday that Trump was trying to divide Iranians and force Iran to surrender through the blockade.

Trump on Tuesday discussed with US oil companies how to mitigate the impact of a possible extension of the US blockade on Iranian ports for months if needed, the White House said on Wednesday.