Iran set ablaze two tankers in Iraqi waters as it stepped up attacks on oil and transport facilities across the Middle East, warning the world should be ready for oil at $200 a barrel in defiance of President Donald Trump's claim that the US had already won the war.
The joint US and Israeli air strikes on Iran which began almost two weeks ago has so far killed around 2,000 people and thrown global energy markets and transport into chaos.
The conflict has spread across the Middle East and prompted plans for a record release of strategic oil reserves to dampen one of the worst fuel shocks since the 1970s.
The United Nations Children's Fund (UNICEF) said more than 1,100 children had been killed or injured.
At a campaign-style rally in Kentucky ahead of November midterm elections in which his Republican party is trailing badly, Mr Trump said the United States had won the war but did not want to have to go back every two years.
"We don't want to leave early, do we?" he said. "We got to finish the job."
Iran has made clear it intends to impose a prolonged economic shock, with the spokesperson for Iran's military command saying in remarks directed at the US: "Get ready for oil to be 200 dollars a barrel, because the oil price depends on regional security, which you have destabilised."
Iranian explosive-laden boats appear to have attacked two fuel tankers in Iraqi waters setting them ablaze and killing one crew member after projectiles struck three merchant vessels in Gulf waters, port officials, maritime security and risk firms said.
"This appears to mark a direct and forceful Iranian response to the IEA's overnight announcement of a massive strategic reserve release aimed at cooling runaway prices," said Tony Sycamore, analyst at IG.
Iran also targeted fuel tanks at a facility in Bahrain's Muharraq, the interior ministry said.
The International Energy Agency, made up of major oil consuming nations, recommended releasing 400 million barrels from global strategic reserves to dampen one of the worst oil shocks since the 1970s, the biggest such intervention in history.
Mr Trump said the IEA decision "will substantially reduce oil prices as we end this threat to America and the world."
US Energy Secretary Chris Wright said Mr Trump had authorised the release of 172 million barrels from the US Strategic Petroleum Reserve from next week.
Crucial oil route blocked
So far there has been no sign that ships can safely sail through the Strait of Hormuz, the now-blockaded channel along the Iranian coast that serves as a conduit for around a fifth of the world's oil.
An Iranian military spokesperson said the Strait was "undoubtedly" under Iran's control and the G7 group of nations - the United States, Canada, Japan, Italy, Britain, Germany and France - agreed to examine the option of providing escort for ships so they can navigate freely in the Gulf.
Mr Trump said US forces had knocked out 58 Iranian naval ships and that Iran was "pretty much at the end of the line."
He said the US would now "look very strongly" at the Strait of Hormuz, adding: "The straits are in great shape. We've knocked out all of their boats. They have some missiles, but not very many."
Watch: Trump says US looking 'strongly at the straits'
Mr Trump said earlier ships "should" transit through the strait but sources said Iran had deployed about a dozen mines in the channel, further complicating the blockade.
Three crew members were "believed to be trapped" aboard a Thai bulk carrier that was hit by two projectiles yesterday while travelling through the Strait, the vessel's owner said.
Iran's Revolutionary Guards said they had struck the Thai-registered Mayuree Naree, as well as a Liberia-flagged vessel, in the strait because the ships had ignored "warnings".
The Thai ship was struck yesterday morning while transiting through the Gulf waterway, after departing Khalifa port in the United Arab Emirates.
The Omani navy had rescued 20 sailors and efforts were underway to rescue the remaining three, the Thai navy said. Thailand's foreign ministry said all 23 crew members were Thai.
ABC News said the Federal Bureau of Investigation had warned of Iranian drones potentially striking the US West Coast, although Mr Trump said he was not worried that Iran might launch strikes on US soil.
The US State Department also warned that Iran and aligned militias may be planning to target US-owned oil and energy infrastructure in Iraq and warned that militias had in the past targeted hotels frequented by Americans.
US and Israeli officials have said their aim is to end Iran's ability to project force beyond its borders and destroy its nuclear programme.
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An Israeli military official said the military still had an extensive list of targets to hit in Iran, including ballistic missile and nuclear-related sites.
The US military told Iranians to stay clear of ports with Iranian navy facilities, drawing a warning from Iran's military that if the ports were threatened, economic and trade centres in the region would be "legitimate targets".
With pump prices surging, oil prices have become an increasingly urgent element in the calculations behind the war.
