United States President Donald Trump is once again exhorting Iran to make a deal by his deadline, saying a "whole civilisation will die tonight" if an agreement is not reached to end the conflict.
"A whole civilisation will die tonight, never to be brought back again. I don't want that to happen, but it probably will," Trump said in a post on Truth Social on Tuesday.
"We will find out tonight, one of the most important moments in the long and complex history of the World."
Trump has given Iran until 8pm in Washington on Tuesday (10am on Wednesday AEST) to end its blockade of Gulf oil, saying he will otherwise destroy every bridge and power plant in Iran within four hours.
However, Iran shows no sign of agreeing to Trump's demand that it open the Strait of Hormuz by his deadline or suffer what would be the biggest escalation yet of the war.
A senior Iranian source told Reuters that Iran had rejected a proposal conveyed by intermediaries for a temporary ceasefire.
Talks on a lasting peace could begin only after the US and Israel end their strikes, provide a guarantee they will not resume and offer compensation for damages.
Any future settlement must leave Iran in control of the strait, imposing fees on ships that use it, the source said on condition of anonymity.
As the clock ticked down on Trump's deadline to unleash "hell", global markets were largely frozen, hesitant to bet on whether Trump would follow through on his threats or call them off as he has in the past.
Deprived of oil 'for years'
Iran has rejected Trump's demands and threatened to retaliate against infrastructure belonging to US allies in the Gulf, whose desert cities would be uninhabitable without power or water.
According to Reuters, Iran's top joint military command said it would continue its attacks on US and Israeli military, security and economic infrastructure in the region with "greater intensity" and in a way that will "deprive them of the region's oil and gas for years."
In the latest attacks overnight, a synagogue in Tehran was destroyed by what Iran described as Israeli air strikes.
Israel's military had no immediate comment.
Without waiting for Trump's deadline to expire, Israel threatened Iranian civil infrastructure on Tuesday, warning Iranians in a Persian-language social media post to stay away from railways: "Your presence on trains and near railway lines endangers your life."
Trump has abruptly called off similar threats in the past several weeks, citing what he has described as productive negotiations with unidentified figures in Iran, though Iran has denied any substantive talks have taken place.
The two countries have exchanged proposals, with Pakistan acting as the main go-between, but there has been no sign of compromise, with both sides claiming to have won the war and demanding concessions from their foes to end it.
Iran's ambassador to Pakistan said on Tuesday "positive and productive endeavours" by Islamabad to mediate an end to the war were "approaching a critical, sensitive stage", but gave no further details.
A proposal brokered by Pakistan would call for a temporary ceasefire and the lifting of Iran's effective blockade of the strait, while putting off a broader peace settlement for further talks, according to a source familiar with the plan.
But Iran's 10-point response would require a permanent end to the war, the lifting of sanctions and a promise of the reconstruction of Iranian sites damaged by the Israeli-US strikes.
It would also include a new mechanism to govern passage through the Strait of Hormuz — previously an open international waterway through which a fifth of global oil and liquefied natural gas typically passed.
Since the US and Israel attacked Iran on 28 February, Iran has effectively closed it to nearly all ships apart from its own.
Trump imposed his latest deadline on Iran in a social media message on Sunday that declared "Open the F----in' Strait, you crazy bastards, or you'll be living in Hell — JUST WATCH!", language Iranian officials described as desperate or even mad.
Iran's envoy to the United Nations said Trump's threats were "direct incitement to terrorism and provide clear evidence of intent to commit war crimes under international law".
Trump weighs plea for Iran deadline extension
Trump was looking at a request on Tuesday from mediator Pakistan to extend his Iran attacks deadline by two weeks — hours after warning that "a whole civilisation will die" if Iran fails to make a deal.
Trump's latest wildly provocative threat against Iran prompted severe criticism, with former allies calling for his removal from office.
But as the clock ticked towards Trump's deadline, Pakistani Prime Minister Shehbaz Sharif appeared to offer an off-ramp.
"To allow diplomacy to run its course, I earnestly request President Trump to extend the deadline for two weeks," Sharif said on X, saying that efforts to resolve the crisis were moving "steadily, strongly and powerfully."
Sharif said he had also asked Iran to reopen the Strait of Hormuz shipping channel for the same two-week period.
The White House said Trump — who has threatened massive attacks against Iran's power plants and bridges to take the country back into the "Stone Age" — was looking at the Pakistani request.
"The President has been made aware of the proposal, and a response will come," White House press secretary Karoline Leavitt told Agence France-Presse in a statement.
Trump, who has previously pushed back the deadline on a number of occasions, separately told Fox News that the United States was in "heated negotiations" but declined to say how they were going.
Since 28 February, the US and its ally Israel have levelled Iranian military targets, killed the country's top leadership and devastated parts of its infrastructure.
US vice president JD Vance offered his own threatening assessment of what may follow, warning Tehran that US forces have tools they "so far haven't decided to use" against the Islamic Republic.
'Extremely sick person'
On Truth Social, Trump left the door open for a last-hour agreement.
"Now that we have Complete and Total Regime Change, where different, smarter, and less radicalised minds prevail, maybe something revolutionarily wonderful can happen, WHO KNOWS? We will find out tonight," he wrote.
Trump's sabre-rattling has appalled critics.
"This is an extremely sick person," top US Senate Democrat Chuck Schumer posted on X.
Former vice president Kamala Harris, Trump's Democratic rival in the 2024 US election, called Trump's threats "abhorrent" and accused the Republican of planning war crimes.
Even some political figures once close to Trump are calling for his removal through the US Constitution's 25th Amendment, which provides for a transfer of power if a president is unable to govern, particularly in the event of illness.
"25TH AMENDMENT!!! Not a single bomb has dropped on America," former congresswoman Marjorie Taylor Greene wrote on X. "We cannot kill an entire civilisation. This is evil and madness."
Anthony Scaramucci, a financier who briefly worked in Trump's first White House, urged Republicans to "wake up" because the president "is calling for A NUCLEAR STRIKE. Seek his removal immediately."
Team Trump denied Vance's remarks contained any suggestion of nuclear attack.
"Literally nothing [Vance] said here 'implies' this, you absolute buffoons," the White House said on X.
The post was in response to one from an account associated with Harris, which said Vance implied Trump "might use nuclear weapons."
For the latest from SBS News, download our app and subscribe to our newsletter.
