President Donald Trump on Wednesday pledged that the US would bomb Iranian civil infrastructure every time Tehran fires at ships in the strategic Strait of Hormuz.

"From this point forward, any time the Islamic Republic of Iran shoots at a ship in the Strait of Hormuz, whether it be by missile, rocket, drone, or any other device or weapon, the United States will bomb and destroy one bridge or power plant," Trump wrote on his Truth Social network.

Trump said this included Iranian facilities "located next to, or in, the capital city of Tehran."

Trump's threat came shortly before he headed to an airbase for the return of the remains of three US troops killed in Iranian attacks on US military facilities in the Gulf.

The US president said he was going to "honour our heroes and they're indeed great heroes."

"All of them said, very strongly, that we can't let Iran have a nuclear weapon, so we're going to honour them... For me it's one of the hardest things to do as president but it has to be done," he added.

Trump rejected polls that show the Iran war is unpopular with US voters ahead of midterm elections in November, with rising oil prices fueling a spike in the cost of living.

The war has already cost Washington $37.5 billion (€32.8bn).

"Americans don't want high gasoline prices but they're not against the war, that just came out loud and clear," Trump said.

Attacks shake Iran and Jordan

Washington has stepped up strikes against Iran since a preliminary ceasefire deal collapsed amid fighting over the strait, carrying out 11 straight days of attacks on the Islamic republic.

Iran has retaliated by firing at US military facilities in the Gulf.

Jordan’s military said it intercepted four Iranian missiles over Aqaba on Wednesday, while two others fell in “uninhabited areas”.

Plumes of smoke could be seen overhead in videos filmed by people in the nearby Israeli city of Eilat. Jordan said it also intercepted four Iranian drones.

Iran has avoided striking Israel since hostilities resumed last month, apparently hoping to keep it from reentering the war.

But the attack on Aqaba, within sight of Israel’s Eilat, raised concerns over a further widening of the conflict after an agreement to halt hostilities collapsed.

Another missile alert sounded in Bahrain, and Saudi Arabia warned residents of the Persian Gulf city of Dammam to seek shelter. Saudi authorities later said the danger had passed, without elaborating.

Iran's state-run IRNA news agency reported explosions across several provinces. Iran's Health Ministry says US strikes over the past 11 days have killed 53 people, including six women and three children, and wounded nearly 600 people.

Iran's IRGC insisted its retaliatory attacks would continue.

The US military said Wednesday's dignified transfer service at Dover Air Base in Delaware was for two service members killed in an Iranian attack on a base in Jordan and a service member killed during a controlled detonation of a drone in Iraq.

A third service member remains missing from the Jordan attack.

Trump has vowed to avenge the deaths of all US troops "many times over" and stepped up threats to target civilian infrastructure. The total number of US deaths since the start of the war is 18.

The US president also repeated threats on Tuesday to strike what he said was a secret Iranian nuclear complex called Pickaxe Mountain. Iran denies the existence of any facility at the site, which it calls Kolang mountain.

Additional sources • AP, AFP