The U.S. military declared on Saturday it had damaged an Iranian bunker housing weapons threatening oil and gas shipments in the Strait of Hormuz, as thousands of Iranians marked Eid al-Fitr with prayer.
The U.S. statement appeared designed to calm energy market concerns and reassure Washington’s skeptical international allies, more than 20 of whom issued a statement vowing to back efforts to re-open the key sea lane.
Admiral Brad Cooper, head of U.S. Central Command, said U.S. war planes had dropped 5,000-pound bombs on an underground facility on Iran's coast that was storing anti-ship cruise missiles, mobile missile launchers, and other equipment.
"We not only took out the facility, but also destroyed intelligence support sites and missile radar relays that were used to monitor ship movements," Cooper said in a video statement.
A statement from the leaders of mainly European countries, including the UK, France, Italy, and Germany, but also South Korea and Australia as well as the UAE and Bahrain, condemned the "de facto closure of the Strait of Hormuz by Iranian forces."
"We express our readiness to contribute to appropriate efforts to ensure safe passage through the Strait.
"We welcome the commitment of nations who are engaging in preliminary planning," they said.
As consumers count the cost of attacks on oil and gas facilities in the Gulf, including the world's largest liquefied natural gas hub, U.S. President Donald Trump has criticized NATO allies as "cowards" and urged them to secure the strait.
Iran has effectively restricted traffic through the channel, through which around a fifth of the world's crude oil and liquefied natural gas passes during peacetime.
Foreign Minister Abbas Araghchi said Tehran had only imposed restrictions on vessels from countries involved in attacks against Iran, and would offer assistance to others that stayed out of the conflict.
Iran also denies claims — cited in the 20-country joint statement — that it has deployed mines in the channel.
The standoff has sent crude oil prices soaring, with a barrel of North Sea Brent crude up more than 50 percent over the past month and now comfortably more than $105.
Analysts, meanwhile, say Iran's Islamic government has survived the loss of its top leaders, and its strike capacity is proving more resilient than expected, with surviving drones, missiles, and launchers apparently able to sustain retaliatory strikes for several more weeks.
"They're showing a lot of resilience that we didn't perhaps expect, that the U.S. didn't expect, when it took this on," Neil Quilliam, of Chatham House to the London-based think tank's podcast.
"But the IRGC, the Iranian regime — it's deep, it has these roots, this institutional strength... it's quite remarkable how they've managed to endure," he added.
Meanwhile, Tehran marked the end of Ramadan 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 was killed in a U.S.-Israeli strike, has remained out of the public eye.
Instead, the head of the judiciary, Gholam Hossein Mohseni Ejei, attended prayers at central Tehran's Imam Khomeini grand mosque, which was overflowing, with worshippers flooding the streets outside.
The previous evening, airstrikes had darkened the mood as the city celebrated Nowruz, the Persian New Year.
"The atmosphere of the New Year was spreading through the city.
Places like Tajrish or Golestan Shahrak, where I went, were full of well-dressed and beautiful women buying flowers," said Farid, an advertising executive, reached by AFP through an online message.
"The Israeli attacks happening exactly at the moment of the New Year were deeply upsetting.
"The thought that some people could be dying right at the New Year dinner table was painful," the executive added.
Iran's ally Russian President Vladimir Putin sent greetings to Khamenei, saying he "wished the Iranian people strength on overcoming these severe trials and emphasized that during this difficult time, Moscow remained a loyal friend and reliable partner of Tehran."
According to Iran's atomic energy organization, the U.S. and Israel targeted a plant at Natanz in Isfahan province, which hosts underground centrifuges to enrich uranium for Iran's disputed nuclear program and was already damaged in last year's June war.
"Following the criminal attacks by the United States and the usurping Zionist regime against our country, the... Natanz enrichment complex was targeted this morning," the organization said, in a statement carried by the Tasnim news agency.
No leakage of nuclear materials was reported, it added.
The head of the International Atomic Energy Agency (IAEA), Rafael Grossi, called for "military restraint to avoid any risk of a nuclear accident," but the UN watchdog confirmed that no increase in off-site radiation levels had been reported.
Asked about Natanz, the Israeli military said it was "not aware of a strike."
Iran meanwhile launched what a U.K. official told AFP was an "unsuccessful" ballistic missile attack on the U.K. and U.S. military base on Diego Garcia, an island in the Indian Ocean around 2,500 miles from Iran.
On Friday, the U.K. government said it would allow Washington to use its bases in Diego Garcia and Fairford in England to target Iranian "missile sites and capabilities being used to attack ships in the Strait of Hormuz."
The U.K. official confirmed that the failed missile strike took place before this announcement.