The leaders of Iran, Israel and the United States have all voiced defiance and vowed to fight on as the Middle East war approached the two-week mark, killing thousands of people, disrupting the lives of millions of others and shaking financial markets.
New Iranian Supreme Leader Mojtaba Khamenei issued his first comments, read out by a television presenter, vowing to keep the Strait of Hormuz shut and calling on neighbouring countries to close US bases on their territory or risk Iran targeting them.
"I assure everyone that we will not neglect avenging the blood of your martyrs," said the hardline cleric, who is close to Iran's top military force. It was not clear why he did not appear in person.
However, Iran's foreign ministry later said ships could pass through the Strait, a conduit for 20% of global oil supply, if they co-ordinated with Iran's navy.
The prospect that one of the most severe disruptions ever to hit global energy supplies could drag on sent oil prices surging back above $100 a barrel, after falling earlier in the week on hopes of a swift end to the conflict.
Huge explosions hit central Tehran this morning, according to Iranian state television, which added that strikes had hit an area not far from where a pro-government demonstration was being held.
Earlier, state TV broadcast images of crowds gathering in Tehran and other major cities to mark Quds Day, the last Friday of Ramadan, in support of the Palestinian cause.
The US military has announced that the entire crew of six was killed when an aerial refueling aircraft crashed in Iraq - an incident it said was not caused by "hostile fire."
"All six crew members aboard a US KC-135 refueling aircraft that went down in western Iraq are now confirmed deceased," US Central Command said in a social media post.
"The circumstances of the incident are under investigation. However, the loss of the aircraft was not due to hostile fire or friendly fire," said the military command, which is responsible for US forces in the Middle East.
This brings the total of confirmed US deaths in the operation against Iran to 13.
US 'totally destroying' Iranian regime, says Trump
Israeli Prime Minister Benjamin Netanyahu held his first news conference since the US and Israeli airstrikes on Iran started on 28 February, taking questions via video-link and issuing a veiled threat to kill Mr Khamenei and defending the military assault.
"I will not detail the actions we are taking. We are creating the optimal conditions for toppling the regime but I won't deny that I can't tell you with all certainty that the people of Iran will topple the regime - a regime is toppled from the inside," Mr Netanyahu said.
"But we can definitely help and we are helping."
US President Donald Trump weighed in on social media, saying the US was "totally destroying the terrorist regime of Iran".
"We have unparalleled firepower, unlimited ammunition, and plenty of time - Watch what happens to these deranged scumbags today," Mr Trump said.
"They've been killing innocent people all over the world for 47 years, and now I, as the 47th President of the United States of America, am killing them. What a great honor it is to do so!"
The Israel Defense Forces said its air force had struck more than 200 targets in western and central Iran over the past day, including ballistic missile launchers, air defence systems and weapons production sites, as part of its operation dubbed Operation Roar of the Lion.
Overnight, Iran launched a barrage of missiles towards Israel, undermining earlier US and Israeli claims to have knocked out much of Iran's stock of long-range weapons.
Medics in Israel's north said they had taken 58 people to hospitals, most with minor injuries from glass shards.
Debris from a successful interception also caused minor damage to the façade of a building in central Dubai, the emirate's media office said, adding that no injuries were reported.
In Saudi Arabia, the defence ministry said two drones were intercepted in the east.
The prospect that one of the most severe disruptions ever to global energy supplies could endure sent oil prices up about 9%to $100 a barrel, helping drive down US stocks.
The S&P 500 notched up its biggest three-day percentage drop in a month, and shares in Asia were also under pressure.
In an effort to stabilise global energy markets, the US on issued a 30-day license for countries to buy Russian oil and petroleum products currently stranded at sea.
"The temporary increase in oil prices is a short-term and temporary disruption that will result in a massive benefit to our nation and economy in the long-term," Mr Bessent said in the statement, echoing earlier comments from President Trump.
Political fallout in US, investigation suggests targeting error for fatal school strike
Mr Trump, who has already declared that the US and Israel won the war, said the United States stood to make significant money from oil prices driven higher because of supply issues tied to the closure of the Strait of Hormuz, through which a fifth of global oil normally passes.
"The United States is the largest Oil Producer in the World, by far, so when oil prices go up, we make a lot of money. "Stopping Iran from having nuclear weapons was far more important, he said on social media.
Mr Trump's comments angered opposition Democrats, who accused the Republican president of caring too little about the war's impact on average Americans and demanded more information about civilian casualties, particularly a strike that killed dozens of children at an Iranian girls' school.
The strike on the school in Minab - which killed at least 175 people - was the result of a targeting error by the US military, according to preliminary findings of a US military report.
The investigation found that coordinates for the strike used outdated information.
Mr Trump has repeatedly denied that America was responsible.
His administration has not provided a public assessment of the expected cost or duration of the war, which is unpopular with the American public, or a strategy for Iran after the fighting stops.
The president and top aides have also given conflicting reasons for starting to fight.
The death toll has risen to more than 2,000 people, most in Iran.
Almost 700 have died in Lebanon, where Israel has targeted central Beirut and ordered residents out of a swathe of the south in an offensive against the Iran-backed Hezbollah group.
France's President Emmanuel Macron said one soldier had died and several were wounded during an attack in northern Iraq, hours after an Italian base was also targeted in the area.
Two tankers were set ablaze in the Iraqi port of Basra earlier this week after being hit by suspected Iranian explosive-laden boats and other ships have been struck in the Gulf near the Strait of Hormuz.
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