THE United States carried out strikes on Iran early today, hours after President Donald Trump vowed to reinstate a US blockade of Iranian ports and charge ships for safe passage through the Strait of Hormuz.

Iran responded with attacks on regional allies of Washington.

The latest exchange of fire leaves in tatters an interim deal meant to pause the fighting, reopen a waterway that is key to world energy supplies and give negotiators time to hammer out a permanent end to the war.

A fifth of all traded crude oil and natural gas passed through the strait before the US and Israel sparked the war by attacking Iran on February 28.

The interim deal was supposed to reopen the waterway, but the US military provoked the Iran to attack ships by encouraging vessels to move through the strait on a route outside Tehran’s control.

Washington has now threatened to reopen the strait by force — but experts say that will require a much bigger armada and possibly tens of thousands of US ground troops, so Mr Trump might back down, as he often has in the past.

The Pentagon’s Central Command said that it had struck several areas in Iran, targeting “coastal defence systems, missile and drone sites and maritime capabilities.”

Iran responded with attacks targeting Bahrain, Jordan and three tankers passing through the strait.

Two of the ships were associated with the United Arab Emirates and were set on fire for a while. The Emirati Defence Ministry said that the attack on the tankers Mombasa and Al Bahiyah had killed one mariner and wounded eight. The Emirates threatened to retaliate.

Dutch shipping firm Stolt Tankers said one of its ships, the Stolt Magnesium, had come under attack off Oman. Despite a fire in the engine room, all the mariners were safe.

Iran’s paramilitary Revolutionary Guard said that the Mombasa and Al Bahiyah had “ignored repeated warnings.”

Hours after the US said it had ended strikes, the Iranian coastal city of Bushehr was hit in at least four locations, the state-run IRNA news agency reported.

“We are reinstating the Iranian blockade,” Mr Trump said on social media on Monday night.

He said that the US would impose a fee for protecting other ships of 20 per cent of the cargo’s value to help cover “any and all costs necessary to do the job of providing safety and security.”

That represents a break with long-standing US policy and with recent promises to keep strait open to all without tolls.