President Donald Trump warned that "a whole civilization will die" in Iran on Tuesday if the country does not heed his ultimatum to accept US war demands.
"A whole civilization will die tonight, never to be brought back again. I don't want that to happen, but it probably will," Trump wrote on his Truth Social platform.
Trump did not give details but he has already said the US military could bomb Iran's bridges, power plants and other civilian infrastructure into the "stone age."
Trump has announced a deadline of midnight GMT Tuesday for Iran to end its de facto closing of the Strait of Hormuz, a narrow, strategic waterway used to transport oil and other commodities.
On Monday, he said a temporary cease-fire proposal being circulated was insufficient.
Trump had repeatedly pushed back deadlines for Tehran to cut a deal or open the Strait of Hormuz, but his latest deadline for Tuesday came with his most perilous threat yet.
Trump's previous deadline was weeks ago, but it was postponed several times as the Republican president oscillated between heated threats, announced delays and proclamations that the negotiations were going well, sometimes in the same statement.
Meanwhile, Iran said that Tehran is ready for 'all scenarios' after Trump threats
Earlier, Iran had rejected US pressure, with state media reporting that the authorities are insisting that instead of just a cease-fire it wants a full end to the war.
Iranian envoy had also said that Tehran will not “stand idle’ if Trump follows through on ‘war crime’ threats.
Amir-Saeid Iravani, Tehran’s representative at the U.N., said that Trump’s threats “constitute incitement to war crimes and potentially genocide.”
During a Security Council session on the Strait of Hormuz, Iravani urged the international community to call out Trump’s rhetoric before it’s too late.
“Iran will not stand idle in the face of such egregious war crimes. It will exercise, without hesitation, its inherent right of self-defense and will take immediate and proportionate reciprocal measures,” he said.
In his Truth Social post, Trump left the door open for a last-hour agreement.
"Now that we have Complete and Total Regime Change, where different, smarter, and less radicalized minds prevail, maybe something revolutionarily wonderful can happen, WHO KNOWS? We will find out tonight," he wrote.
Trump said Monday that starting late evening in Washington, DC on Tuesday, US forces would destroy "every bridge in Iran" and cripple "every power plant" in the country -- something that many experts say would be a blatant war crime.
US and Israeli warplanes have been continuously bombing Iran since February 28 and on Tuesday, even before Trump's threat about ending "civilization," Tehran said that its crucial oil export terminal on Kharg island was under attack.
As Trump's deadline approaches, Kuwait has asked its residents to avoid going outside from midnight until Wednesday morning.
"The interior ministry tells citizens and residents that it is crucial to stay at home and avoid going out, unless absolutely urgent, from midnight Tuesday April 7 until 6am Wednesday April 8," it said in a statement shared on X.
Meanwhile, Bahrain's main port will suspend operations starting early Wednesday.
"Operations in Khalifa Bin Salman Port will be temporarily suspended from early April 8. We continuously adapt our operations to the circumstances and have, as a result, temporarily paused operations in recent weeks when needed," APM Terminals Bahrain, which operates the port, according to a report by AFP.
The US has also urged its citizens to reconsider travelling to Saudi Arabia to take part in the Hajj pilgrimage next month due to security concerns, according to a statement posted by the US embassy in Riyadh.
Pointing to a recent travel advisory cautioning against visiting Saudi Arabia due to Iranian missile and drone attacks, the statement said that "due to the ongoing security situation and intermittent travel disruptions, we advise reconsidering participation in Hajj this year".
As Tehran intensified attack on its neighbours, Bahrain's foreign minister warned Tuesday that the patience of Gulf states is not limitless.
"Our countries have exercised considerable restraint and patience in the face of ongoing Iranian aggression, but this restraint cannot be expected to continue without limit," Abdullatif bin Rashid Al Zayani told reporters.
"Our rights under international law cannot be diminished by inaction, nor can accountability be avoided by turning a blind eye."
Pope Leo, meanwhile, had criticised the US president saying that the threat to entire Iran population as 'unacceptable'.
(With inputs from AFP)