DUBAI - The United States struck bridges in Iran, and Tehran responded by hitting a power and desalination plant in Kuwait on Friday, as the two sides risked further escalation by expanding their targets to include infrastructure.

At sea, where the renewed conflict has again cut off energy supplies from the Gulf, U.S. Marines boarded a tanker near the Strait of Hormuz. Armed men seized another vessel off Yemen, raising concern over security in the Middle East's other big choke point for oil shipments at the mouth of the Red Sea.

Iran's semi-official Tasnim news agency reported late on Friday that the Revolutionary Guards navy had "targeted" a Thai-flagged ship trying to get through the Strait of Hormuz. It did not give further details.

Washington 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 emerged on Friday, benchmark Brent crude oil prices climbed 3% and were on track for a third consecutive weekly gain. Global share prices fell, with Wall Street opening sharply lower.

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.

Such moves risk provoking Iran to escalate in turn by hitting the vital infrastructure of vulnerable neighbouring Arab states, or having its allies in Yemen further disrupt global energy supplies by attacking shipping from the Red Sea.

UN CONCERNED OVER 'ATTACKS ON CIVILIAN INFRASTRUCTURE'

U.N. Secretary-General Antonio Guterres was concerned about the escalation, particularly over "attacks on civilian infrastructure in Iran and across the region," his spokesperson said.

In the latest strikes, the U.S. military's Central Command included "military logistics infrastructure" in the list of targets it said it had hit, the first time it has mentioned infrastructure in more than a week.

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.

Videos verified by Reuters showed rubble, broken railings and a damaged vehicle on a smashed bridge in Bandar Khamir. One clip showed a fire.

Reuters was unable to confirm details in other reports, which described deadly attacks including one which killed a woman and wounded her child in the port of Bandar Abbas.

Iran announced attacks on Gulf countries that host U.S. airbases, including Bahrain, Qatar and Kuwait.

Authorities in Kuwait said one of the country's power generation and water desalination stations had been hit in an Iranian attack, causing damage to facilities, a fire and the disruption of a large number of electricity generation units.

Firefighters brought the blaze under control, while technical teams began assessing the damage, securing the station and working to restore power generation as soon as possible, the Ministry of Electricity, Water and Renewable Energy said.

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 that helped push the United States to declare the war's first ceasefire a week later.

FEUD OVER STRAIT

Iran said it had struck U.S. bases in Kuwait, Qatar and Bahrain, and a U.S. radar station in Oman. Explosions were heard in the Qatari capital Doha, where the interior ministry said a child was wounded by shrapnel.

Iran also said it fired at Syria, apparently for the first time in the war, targeting what it described as a U.S. special forces base in Tanf, which Damascus and Washington say U.S. forces vacated earlier this year. A Syrian military source said the strike hit near the base and caused no damage or casualties. CENTCOM said no U.S. troops were killed or captured.

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.

In the latest action at sea, the U.S. military said it had boarded a tanker to enforce the blockade, releasing photos of Marines rappelling down from a helicopter onto the deck where one posed in front of an Iranian flag.

Beyond the Gulf, armed assailants boarded and seized a small chemical tanker off Yemen in the Gulf of Aden, close to the mouth of the Red Sea.

One maritime security source said the incident appeared to be related to Somali piracy rather than action by Iran's Yemeni allies, the Houthis. But security sources in the Horn of Africa have spoken in the past of concern about the potential for the Houthis to assist, encourage or arm pirates in the area.

Iran has signalled that it could prod its Houthi allies in Yemen to close another key strait: the Bab al-Mandeb at the mouth of the Red Sea, potentially cutting off the main alternative route for Middle East oil bypassing the Gulf. Sources have told Reuters Iran has already instructed the Houthis to act if Washington attacks Iran's infrastructure.

(Reporting by Reuters bureaux; Writing by Peter Graff and Andrew Heavens; Editing by Jon Boyle and Hugh Lawson)

A damaged portion of a bridge in the aftermath of a strike, in Bandar Khamir, Hormozgan province, Iran July 17, 2026 in this screen grab obtained from social media video. Social Media/via REUTERS Social Media Reuters

People stand near a damaged portion of a bridge in the aftermath of a strike, in Bandar Khamir, Hormozgan province, Iran July 16, 2026 in this screen grab obtained from social media video. Social Media/via REUTERS Social Media Reuters

Copyright Reuters or USA Today Network via Reuters Connect.

This story was originally published July 17, 2026 at 10:59 AM.

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