Tehran, Iran - Iran on Sunday threatened to attack key infrastructure across the Middle East if US President Donald Trump follows through on his vow to "obliterate" the Islamic republic's power plants unless the Strait of Hormuz swiftly reopens.

Trump, after signaling he may wind down the war, ratcheted up pressure on Iran's leadership, announcing a countdown over the Islamic republic's de facto blockade on the crucial trade route.

"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 posted on his Truth Social platform.

But Iran's military operational command responded that if the country's facilities were hit, "all energy, information technology and desalination infrastructure belonging to the US" in the region would be targeted.

World Venezuela reshapes military in big shift toward Washington

Tehran's defiance comes after it retaliated for an attack on its nuclear site at Natanz with two direct hits on southern Israel.

Slipping past the country's air defenses, the missiles crashed into the towns of Dimona, which hosts a nuclear facility, and Arad, wounding more than 100 people.

Israel said it launched a fresh wave of strikes on Iranian capital Tehran on Sunday in response.

But Trump turned his attention to the blockaded strait, which typically carries a fifth of the global crude oil trade.

The standoff has rattled markets and sent oil prices soaring, with North Sea Brent crude now trading above $105 a barrel, as concerns grow about the long-term consequences for the global economy.

Trump has slammed NATO allies as "cowards" and urged them to secure the strait.

A total of 22 countries – including the UK, France, Italy, Germany, South Korea, Australia, the UAE, and Bahrain – condemned on Saturday the "de facto closure of the Strait of Hormuz by Iranian forces."

As thousands more American Marines head to the Middle East, US Central Command said bunker-busting bombs were dropped on an underground Iranian coastal facility this week, claiming it had degraded Iran's ability to threaten freedom of navigation in the strategic waterway.

Iran's missile attack on Israel indicated that its arsenal still poses a threat across the region, even after Trump and Netanyahu claimed to have decimated Tehran's forces.

The Iranian hits on the towns of Arad and Dimona tore open the fronts of residential buildings and carved craters into the ground – among the most destructive attacks of the three-week war.

AFP footage from Arad showed rescue workers sifting through rubble for wounded people in a bombed-out building.

Tattoos Why a tattoo could hold the key to solving the Nancy Guthrie kidnapping case

"There was a 'boom, boom!' My mother was screaming," 17-year-old Arad resident Ido Franky told AFP near the impact site, where a correspondent with the outlet saw three damaged buildings and firefighters reported a blaze.

"This was terrifying... this town had never seen anything like this."

Dimona hosts what is widely believed to be the Middle East's only nuclear arsenal, although Israel has never admitted to possessing nuclear weapons, insisting the site is for research.

The missile fell about three miles from the nuclear facility, leaving about 30 people wounded, according to rescuers.

UN nuclear watchdog chief Rafael Grossi reiterated his call for "military restraint to avoid any risk of a nuclear accident."

Meanwhile, Iran has kept up retaliatory attacks on Gulf nations it accuses of serving as a launchpad for US strikes.

Saudi Arabia said Sunday it detected three ballistic missiles around capital Riyadh and the kingdom's forces intercepted three drones.

The United Arab Emirates said it responded to new missile and drone attacks from Iran, after the Islamic republic warned its neighbor against allowing strikes from disputed islands near the Strait of Hormuz.

Iran also launched an unsuccessful ballistic-missile attack on the US-UK base at Diego Garcia, around 2,500 miles away, a UK official told AFP – which would have been the longest-range Iranian strike yet had it succeeded.

Iran has not claimed this attack.

Analysts say Iran's government has survived the loss of its top leaders and that its strike capacity is proving more durable than expected.

"They're showing a lot of resilience that we didn't perhaps expect, that the US didn't expect, when it took this on," Neil Quilliam of Chatham House told the think tank's podcast.

Tehran, meanwhile, marked the end of Ramadan and the Persian New Year, Nowruz, as the war entered its fourth week.

Iran's supreme leader traditionally leads Eid al-Fitr prayers, but Mojtaba Khamenei – who came to power earlier this month after his father Ali Khamenei was killed – has remained out of the public eye.

Instead, the head of the judiciary, Gholam Hossein Mohseni Ejei, attended prayers at central Tehran's overflowing Imam Khomeini grand mosque.

"The atmosphere of the New Year was spreading through the city," said Farid, an advertising executive reached by AFP through an online message.

But "the thought that some people could be dying right at the New Year dinner table was painful," he added.