The US and Israel have pounded Iran with what the Pentagon and Iranians on the ground called the most intense airstrikes of the war, despite global markets betting President Donald Trump will seek to end the conflict soon.
Raising the stakes for the global economy, Iran's Revolutionary Guards said they would block oil shipments from the Gulf unless US and Israeli attacks cease.
Iran's Islamic Revolutionary Guard Corps also said it launched missiles at Qatar's US-operated Al Udeid base and the Al Harir base in Iraq's Kurdistan.
But the White House reiterated Trump's threat to hit Iran hard over moves to stop the flow of energy supplies through the Strait of Hormuz, where the war has effectively halted one-fifth of the world's oil and liquefied natural gas shipments.
"Today will be yet again, our most intense day of strikes inside Iran: the most fighters, the most bombers, the most strikes, intelligence more refined and better than ever," US Defence Secretary Pete Hegseth told a Pentagon briefing on Tuesday, US time.
In a message posted to his Truth Social platform later in the day, Trump said, "Within the last few hours, we have hit, and completely destroyed" 10 of Iran's "inactive" mine-laying vessels.
US Central Command later said on social media platform X its forces had eliminated 16 Iranian mine-laying vessels near the Strait of Hormuz and posted footage of vessels being blown up.
Tehran residents reached by Reuters described the war's most intense night of bombardment.
"It was like hell. They were bombing everywhere, every part of Tehran," a resident said by phone, speaking on condition of anonymity for security reasons. "My children are afraid to sleep now."
A historic surge in crude oil prices on Monday to nearly $US120 ($A168) a barrel was reversed as Brent crude settled back down below $US90 ($A126) on Tuesday.
A source familiar with Israel's war plans told Reuters the Israeli military wanted to inflict as much damage as possible before the window for further strikes closes, under the assumption Trump could end the war at any time.
Israel's foreign minister, Gideon Saar, said the war would proceed until his country and the US determine the time had come to cease hostilities, but that Israel was not seeking an "endless war".
Trump at a Monday press conference said the US had already inflicted serious damage and predicted the conflict would end before the four weeks he initially set out.
Several congressional aides have said they expect the White House to soon request as much as $US50 billion ($A70 billion) in additional funding for the war.
Several senior Iranian officials voiced defiance.
"Certainly, we are not seeking a ceasefire; we believe the aggressor must be struck in the mouth so that they learn a lesson," Iran's parliament speaker, Mohammad Baqer Qalibaf, posted on X.
Foreign Minister Abbas Araqchi told PBS that Tehran was unlikely to resume negotiations with the US.
A spokesperson for the Revolutionary Guards said Tehran would not allow "one litre" of Middle Eastern oil to reach America or its allies while US and Israeli attacks continue.
"We are the ones who will determine the end of the war," the spokesperson said.
More than 1300 Iranian civilians have been killed since the US and Israeli air strikes began on February 28, according to Iran's UN ambassador, Amir Saeid Iravani.
Scores have also been killed in Israeli attacks on Lebanon to root out the Iran-backed group Hezbollah, which has fired into Israel in solidarity with Iran.
Iranian strikes on Israel have killed 12 people. Iran has struck US military bases and diplomatic missions in Arab Gulf states but also hit hotels, closed airports and damaged oil infrastructure.
In addition to the six US soldiers killed at the outset of the conflict, the Pentagon on Tuesday estimated about 140 American troops have been wounded, the vast majority of them characterised as minor.