The US insists the Strait of Hormuz is open, despite Iran saying it has closed the waterway amid renewed strikes.
Hostilities, which flared up again this week, continued on Saturday after the US said it had struck more than 140 targets across Iran. The attacks were a response to Iranian forces hitting a ship passing through the strait, which it said was using an unapproved route.
Iran has been trying to assert control over the waterway, and early on Sunday said it was closed until further notice.
Iran’s Islamic Revolutionary Guard Corps (IRGC) also launched wide-ranging attacks on US bases and allies across the region on Sunday, marking an escalation in the scale of hostilities.
It said it had hit a US base in Jordan, while the United Arab Emirates (UAE), Qatar, Kuwait, Oman and Bahrain all said they had responded to missiles and drones from Iran.
The BBC has approached US Central Command (Centcom) for comment on the attack in Jordan.
Qatar, a mediator in ceasefire talks, had not been attacked since April, while the UAE had not been attacked since May.
On Sunday evening, Centcom announced another round of strikes against Iran, which it said started at 17:00 ET (22:00 BST) and would “continue degrading their ability to attack civilian mariners and commercial ships freely transiting the Strait of Hormuz”.
On Sunday afternoon, Iran’s IRNA news agency said missiles were launched by the “enemy” towards Qeshm Island – a strategically important island in the Gulf, home to an important IRGC base.
The renewed fire has put in jeopardy an interim ceasefire agreement signed last month, which aimed to reopen the Strait and eventually bring a permanent end to the conflict.
Earlier this week, US President Donald Trump declared the Iranian attacks meant the ceasefire was over, while Iran’s Foreign Minister Abbas Araghchi accused the US of violating the deal.
However, Trump said talks would still continue and mediators were trying to revive the process.
US media reported that Iran told American officials attacks on tankers earlier this week were a mistake and blamed a rogue internal group.
The latest hostilities were sparked after the IRGC said it had fired a naval cruise missile at a vessel that was attempting to sail along an unapproved route.