US forces have struck three Iranian oil tankers, US Central Command says, including one off the coast of Kharg Island, near Iran's key oil export hub.
The strikes were carried out after Iran's Islamic Revolutionary Guard Corps launched ballistic missiles at two US navy ships, Central Command said.
“Let the message to the IRGC be clear: If you shoot at two of our ships, we will impose an even higher economic cost - taking out three of yours," Admiral Brad Cooper, head of US Central Command, said.
Iranian news agency Tasnim reported earlier that four US missiles hit a tanker in the area of Kharg's anchorage.
It quoted local sources as saying there were no casualties and the crew of the tanker were leaving the vessel.
A US military statement said an aircraft carrier and a destroyer evaded "multiple unprovoked Iranian attacks" while patrolling in the region and no US personnel were hurt.
It said two Iranian oil carriers were "permanently disabled" and the third unladen one was destroyed.
The US accused the tankers of being part of a shadow network helping to fund the Revolutionary Guard and its armed proxies in the region.
The US said one tanker was struck off Kharg island and another was struck near Jask.
The unladen tanker was hit in the Gulf of Oman.
The statement shared what it called video footage of the strikes.
The strikes came nearly a week after the US and Iran resumed attacks following a month of relative calm in the on-again, off-again war that began with US and Israeli attacks on February 28.
Both sides have sought to inflict both military and economic pain, and negotiations have collapsed.
"We will not hesitate to defend American forces, and if necessary, destroy Iran’s limited and exposed oil fleet," Cooper said.
The US imposed a blockade on Iranian ports after Iran largely shut the Strait of Hormuz, an important waterway that carried one-fifth of the world's oil supply before the war.
Brent crude futures closed at their highest level since July 24 on Friday, at $US96.28 a barrel as tensions in the Middle East drive global supply concerns.
with Reuters
