The United States expanded its attacks on Iran by striking bridges and an airport in the country's south.
Iran retaliated by targeting U.S. bases across the West Asia and claimed a strike near a U.S. base in Syria.
Renewed fighting has disrupted shipping through the Strait of Hormuz, driving up oil prices and raising fears of a wider regional conflict.
The United States expanded its military campaign against Iran on Friday by striking bridges and an airport, while Tehran responded with attacks on U.S. bases across the West Asia, signalling a further escalation after the collapse of last week's ceasefire.
The latest developments reflect how both sides are continuing to test the limits of escalation without returning to all-out war. According to Reuters, the renewed fighting has again disrupted shipping through the Strait of Hormuz, cutting off global energy supplies from the West Asia, while raising fears the conflict could spread further across the region.
The U.S. military's Central Command said it had struck "military logistics infrastructure" in Iran, the first time in more than a week it had included infrastructure among its stated targets. Reported Reuters, the latest attacks appeared to be limited mainly to southern coastal areas that have already been targeted intensively in recent days.
Iranian state media said at least five bridges had been struck in the south. Seven people were reported killed in attacks on bridges in the southern port of Bandar Khamir, where the train station was also hit. An airport was reported hit further east and away from the coast in Iranshahr, in a province bordering Pakistan. Reuters could not independently verify the reports, which also described other deadly attacks, including one that reportedly killed a woman and wounded her child in the port of Bandar Abbas.
Iran said it had struck U.S. bases in Kuwait and Bahrain, as well as a U.S. radar station in Oman. Explosions were also heard in the Qatari capital, Doha, where the interior ministry said a child was wounded by shrapnel.
Tehran also said it had fired at Syria, apparently for the first time in the war, targeting what it described as a U.S. special forces base in Tanf. Syria says U.S. forces pulled out of the base earlier this year. A Syrian military source said the strike hit near the base and caused no damage or casualties.
The renewed fighting followed the collapse of an interim agreement to end the war on July 7, when Iran struck ships in the Strait of Hormuz and the United States responded with air strikes. According to Reuters, the conflict has once again largely halted traffic through the world's most important energy shipping route, sending oil prices to around $85 a barrel this week.
Iran has announced the closure of the Strait of Hormuz, while Washington has reimposed its blockade of Iranian ports. In one of the latest incidents at sea, the U.S. military said it had boarded the tanker Wen Yao to enforce the blockade, releasing photographs showing U.S. Marines rappelling from a helicopter onto the vessel's deck, where one posed in front of an Iranian flag.
Separately, the British maritime security service UKMTO reported that a tanker had been hit by a projectile on Thursday off the coast of Oman.
While both sides have exchanged strikes daily, they have so far stopped short of escalating beyond parameters set earlier in the war, when civilian infrastructure and major economic targets were mostly deemed out of bounds because of the threat of retaliation.
U.S. President Donald Trump has threatened to launch broad-based air strikes on Iran's infrastructure and has also declined to rule out a ground assault on Iran's coast or islands. U.S. officials have said attacks on southern Iran are designed in part to give Trump options.
However, such moves risk provoking Iran to escalate in turn by hitting infrastructure in neighbouring countries or further disrupting energy supplies by having its allies in Yemen attack shipping from the Red Sea.
Iran has said it would attack civilian infrastructure across the West Asia if Trump follows through on threats to attack Iranian infrastructure. It has also signalled it could prod its Houthi allies in Yemen to close the Bab al-Mandeb at the mouth of the Red Sea, potentially worsening the global energy crisis by cutting off another route for Middle East oil. Reuters reported that sources said Iran has already instructed the Houthis to act if Washington attacks Iranian infrastructure.
The surge in energy prices generated by the conflict has created pressure on Trump to end the war as quickly as possible. However, leaving Iran in control of the Strait of Hormuz would be a strategic embarrassment in a region where U.S. forces have served as the main security guarantor for generations.
In a televised speech on Thursday night, mainly focused on election security, Trump said the United States was "winning big in Iran, and you will see the fruits of that labour very, very shortly."
