The United States has struck bridges in Iran and Tehran has responded by hitting a power and desalination plant in Kuwait.The attacks, on Friday, local time, saw the two sides risk further escalation of the Iran war by expanding their targets to include infrastructure.At sea, where the renewed conflict has again cut off energy supplies from the Gulf, US Marines boarded a tanker near the Strait of Hormuz.Two oil tankers exploded and caught fire after passing through a mined route south of the strait, Iranian media reported, citing the Islamic Revolutionary Guard Corps (IRGC).Armed men seized another vessel off Yemen, raising concern about security in the Middle East's other big choke point for oil shipments at the mouth of the Red Sea.Iran's state television quoted the IRGC as saying that until US "aggression" came to an end, it would not be possible to export chemical fertilisers or even a "single drop of oil and gas" from the region.The interim agreement to end the war collapsed last week when Iran struck ships in the Strait of Hormuz. (Reuters)US and Iranian attacks risk escalation of warWashington and Tehran have been testing the limits of escalation since their ceasefire agreement collapsed last week, raising the prospect of a return to all-out war.After reports of the escalation on Friday, benchmark Brent crude oil prices climbed 3 per cent and were on track for a third consecutive weekly gain, putting political pressure on US President Donald Trump ahead of November congressional elections.Mr 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.US officials have said attacks on southern Iran are designed in part to give Mr Trump options.The latest strikes come after Donald Trump threatened to target Iran's civilian infrastructure. (Reuters: Evan Vucci)Such moves risk provoking Iran to escalate in turn by hitting the vital infrastructure of vulnerable Gulf states, or having its allies in Yemen further disrupt global energy supplies by attacking shipping from the Red Sea.Mohsen Rezaei, an adviser to Iran's supreme leader, warned on Friday against US escalation or any attempt to seize Iranian territory."If US strikes continue for several more days, we will move into a phase of full-scale offensive operations," Mr Rezaei, a former IRGC top commander, told state television.Iran targets Gulf nations after US strikes airport, bridges, train stationUN Secretary-General António Guterres was concerned about the escalation, particularly over "attacks on civilian infrastructure in Iran and across the region", his spokesperson said.The US military's Central Command earlier said its targets included "military logistics infrastructure", the first time it mentioned infrastructure in more than a week.In the latest strikes, Central Command said it re-initiated attacks on Iran for the seventh consecutive night with strikes at 10:30pm Friday, Tehran time."The strikes are designed to continue degrading Iranian military capabilities at the Commander in Chief's direction," the statement on X said.Shortly thereafter, Iranian media reported explosions heard or strikes carried out in the cities of Sirik, Ahvaz and Yazd.Iranian state media previously said at least five bridges were 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.Videos verified by Reuters showed rubble, broken railings and a damaged vehicle on a smashed bridge in Bandar Khamir. One clip showed a fire.Iranian Foreign Minister Abbas Araqchi said that three villagers were killed while crossing the Bandar Khamir Bridge, adding that Iran would not allow their blood "to be in vain".Iran announced attacks on Gulf countries that host US air bases, including Bahrain, Qatar and Kuwait, in addition to a US vessel in the northern Indian Ocean.The IRGC said it attacked a depot of US drones in Bahrain and destroyed Bahrain's main artificial intelligence centre with ballistic missiles and drones.The Iranian navy fired a shore-to-sea cruise missile towards what it called a hostile US vessel in the northern Indian Ocean, state news agency IRNA reported on Friday.Iran's army said the missile launch caused "fear and panic" and forced the vessel to move out of range of Iran's navy.Authorities in Kuwait said one of the country's power generation and water desalination stations had been hit in an Iranian attack, causing damage, a fire and the disruption of a large number of electricity generation units.The rich Arab Gulf states depend on plants that produce electricity and remove salt from seawater to make their desert cities habitable.When Iran hit a Kuwaiti desalination plant on March 30, it was seen as a major escalation.Last month's interim agreement to end the war has collapsed since July 7, when Iran struck ships in the Strait of Hormuz and the United States responded with air strikes. Iran has since announced the closure of the strait, and Washington has reimposed its own blockade of Iranian ports.Reuters