Trump vows tit-for-tat strikes on Iran power plants

President Donald Trump vowed Wednesday to bomb Iranian civil infrastructure every time Tehran fires at ships in Strait of Hormuz, as he attended the return of four more US service members killed in the war.

"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," he wrote on his Truth Social network.

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

Shortly after his post, Trump headed to an airbase for the formal return of the remains of three US troops killed in an Iranian attack on a military base in Jordan, and one killed during a controlled detonation of an unexploded Iranian drone in Iraq.

The US leader saluted as soldiers in ceremonial dress carried flag-draped cases carrying the remains of Lieutenant Tyler Feehan, Sergeant Angel Rampersad, Private Isabella Gonzales and Sergeant Michael Swinton.

Trump said he was there to "honor 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 honor them... For me it's one of the hardest things to do as president but it has to be done."

It was the third "dignified transfer" ceremony Trump has attended since launching the US-Israeli war on Iran in February.

The Republican billionaire 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 the lives of 18 American service members and $37.5 billion in military spending.

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

The United States 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.

Trump has vowed to avenge the deaths of all US troops "many times over" and stepped up threats to target civilian infrastructure. 

The US leader 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.