Iran said Wednesday it was ready for a long war of attrition that would "destroy" the world economy, after firing on two commercial ships and threatening any vessels from the US or its allies.
As Tehran tightened its chokehold on the Strait of Hormuz, a vital sea passage for the global oil trade, US President Donald Trump said the war would end "soon" as there was little left for US forces to target in Iran.
Oil prices have surged since February 28, when the United States and Israel attacked Iran, killed its supreme leader and plunged the Middle East into war.
In an attempt to manage price jumps, the International Energy Agency said its member countries would unlock 400 million barrels of oil from their reserves -- the biggest such release ever.
With the conflict now in its 12th day, Iran's Revolutionary Guard vowed to target "economic centres and banks" that it deems linked to US and Israeli interests, prompting more international firms to evacuate employees from Dubai.
But all eyes were on the Strait of Hormuz, through which 20 percent of global crude and LNG passes.
The US and Israel "must consider the possibility that they will be engaged in a long-term war of attrition that will destroy the entire American economy and the world economy", Ali Fadavi, advisor to the Revolutionary Guards' commander-in-chief, told state television.
Iran said it had struck the Liberian-flagged container ship Express Rome and the Thai bulk carrier Mayuree Naree because they had entered the strait "after ignoring the warnings of the IRGC naval forces".
Oman's navy rescued 20 crew members, but efforts were underway to find three more. Pictures shared by the Thai navy showed black smoke pouring out of the vessel.
- Gulf airport, fuel tanks hit -
Analysts say a prolonged closure of the strait, which also carries a third of the fertiliser for world food production, would have a devastating effect on the global economy, particularly in Asia and Europe.
French President Emmanuel Macron urged G7 leaders to act to restore navigation in the strait "as soon as possible", while the UN asked for all parties to allow humanitarian cargo to transit.
Iran has amplified the economic fallout by targeting US allies in the Gulf.
On Wednesday, drones fell near Dubai airport, injuring four people, the city's government said.
US financial service group Citi and British consulting group Deloitte have asked employees to evacuate their offices in Dubai, sources told AFP.
Drones also hit fuel tanks at Oman's Salalah port, Oman News Agency reported.
Private maritime security company Vanguard Tech reported the suspension of the port's operations after the attack on its southern section.
The economic impact is piling pressure on Trump, who faces accusations that the White House launched the war without preparing for consequences.
"Any time I want it to end, it will end," Trump was quoted as saying in an interview with Axios.
- Fireball in Beirut -
In Israel, Defence Minister Israel Katz said: "This operation will continue without any time limit, as long as necessary."
Israel said it had begun a new "wide-scale wave of strikes" across Iran and against Hezbollah targets in Lebanon's capital Beirut.
Israeli strikes hit an apartment building in central Beirut in the second targeting of the heart of the capital since the Middle East war began.
AFPTV's live broadcast captured the sound of an air strike followed by a fireball erupting in an apartment within a multi-storey residential building in Beirut.
An AFP correspondent saw destroyed walls in the building's seventh and eighth floors, with damaged cars nearby and security forces present at the scene.
When the strike hit, "I ran from room to room, pulled my wife and daughter out of the rooms and hid them behind a wall, then the second strike hit", said Fawzi Asmar, owner of a bakery on the street where the strike took place.
- 'Living despite everything' -
The Israeli-US attacks came weeks after Iranian authorities crushed mass protests, although the United States and Israel say they are not necessarily seeking to topple the Islamic republic.
Iranian authorities warned against dissent at home, with the country's police chief saying protesters would be viewed and dealt with as "enemies".
"All our forces are also ready, with their hands on the trigger, prepared to defend their revolution," national police chief Ahmad-Reza Radan said, in comments aired by IRIB.
In Iran, ordinary people were doing the best they could to adapt to living under frequent US-Israeli strikes.
"We've put our faith in God. For now, there's food in the shops," Tehran resident Mahvash, 70, told AFP journalists in Paris.
"People are calm," said another resident. "They are getting used to living despite everything and adapting -- as best they can -- to this situation."
The United States and Israel launched the war with an attack that killed Iran's supreme leader, Ayatollah Ali Khamenei.
His son Mojtaba Khamenei has been named his successor, though he has yet to appear in public, amid reports that he has been wounded.
"I heard news that Mr Mojtaba Khamenei had been injured. I have asked some friends who had connections," the Iranian president's son, Yousef Pezeshkian, wrote in a post on his Telegram channel.
Tehran's ambassador to Cyprus, Alireza Salarian, told The Guardian newspaper on Wednesday that Khamenei was injured in the same strike that killed his father.
Iran's health ministry said on March 8 that more than 1,200 people had been killed in US and Israeli strikes, and more than 10,000 civilians injured. AFP was not in a position to independently verify the figures.
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W.Blondeel--LCdB