"If Iran doesn't FULLY OPEN, WITHOUT THREAT, the Strait of Hormuz, within 48 HOURS from this exact point in time, the United States of America will hit and obliterate their various POWER PLANTS, STARTING WITH THE BIGGEST ONE FIRST!" Trump said on social media.
A days earlier Trump said the US was close to meeting its goals but insisted other countries should take the lead in policing the Strait of Hormuz, whose near-closure threatens a global energy shock.
The threat of Iranian attacks has kept most ships from getting through the strait, a narrow waterway that serves as the conduit for around a fifth of global oil and liquefied natural gas supplies, threatening a global energy shock. Its near-closure sent European gas prices surging as much as 35 per cent last week.
The latest threat from the White House landed as the conflict entered dangerous new territory.
Israeli officials said that Iranian forces had for the first time fired long-range missiles, expanding the risk of attacks beyond the Middle East, even as an Iranian strike injured dozens of people not far from Israel's nuclear site.
Iran launched two 4000km long-range ballistic missiles at the US-UK military base Diego Garcia in the Indian Ocean, Israeli military chief Eyal Zamir said. The Israeli military said it was the "first time" Iran had used long-range missiles since the United States and Israel began attacking Iran on February 28.
"These missiles are not intended to strike Israel. Their range reaches European capitals - Berlin, Paris, and Rome are all within direct threat range," Zamir said in a statement.
A source at Britain's defence ministry said the attack had occurred before the government gave specific authorisation on Friday for the US to use British military bases to carry out strikes on Iranian missile sites.
More than 2000 people have been killed in Iran since the US and Israel began their attacks. In Israel, 15 people have been killed in Iranian strikes since the war started.
Late on Saturday, Iranian missiles hit the southern Israeli cities of Dimona and Arad, injuring dozens of people, including children, in separate strikes.
Iran's Revolutionary Guards said in a statement early Sunday that they targeted "military installations" and security centres in southern Israel.
Israeli army spokesperson Brigadier General Effie Defrin said in a post on X that the country's air defences were functioning but did not intercept the strikes.
"We will investigate the incident and learn from it," he said.
Israel's secretive nuclear reactor is about 13km southeast of Dimona.
Both cities lie near several military sites, including Nevatim Air Base, one of the country's largest.
"This has been a very difficult evening in the battle for our future," Israeli Prime Minister Benjamin Netanyahu said in a statement released by his office following the strike on Arad.
"We are determined to continue striking our enemies on all fronts," the statement said.
Trump has sent mixed messages about US goals throughout the war, now in its fourth week, leaving allies struggling to respond.
Saturday's ultimatum was the sharpest whiplash yet. Trump's rhetoric pivoted from a drawdown to an explicit 48-hour countdown to strike Iran's power infrastructure, even as US Marines and heavy landing craft continue heading to the region.
US voters appear increasingly concerned that the war could expand.
Energy price shocks are fuelling inflation, hitting consumers and businesses hard, a major political liability for Trump as he seeks to justify the war to the public before November elections in which control of Congress is at stake.
Trump had also accused NATO allies of cowardice over their reluctance to help open the strait. Some allies have said they will consider it, but most say they are reluctant to join a war that Trump started without consulting them.
Iranian media said US and Israeli forces had attacked the Shahid Ahmadi-Roshan Natanz enrichment complex on Saturday morning.
Technical experts found no radioactive leaks, and nearby residents were not at risk. Israel said it was unaware of such a strike, while the head of the International Atomic Energy Agency said it was investigating.
Iranian media later reported strikes on a passenger terminal in the southern port of Bushehr and an empty passenger ship at nearby Kharg Island. The island, where Iran loads nearly all its oil exports, is seen as a potential target if Washington decides to hit Iranian energy or to use ground troops to seize it.
Iran said it fired drones at US bases in the United Arab Emirates and Kuwait used to stage attacks on Iranian islands in the Gulf.
Israel also attacked Beirut, saying it was targeting the Iran-backed Lebanese Hezbollah militia, part of the deadliest spillover from the war on Iran.
Israel said its aircraft had attacked ballistic missile production sites around Tehran.
