The US president has warned of intensified military action if Tehran fails to reopen the Strait of Hormuz by Tuesday evening (EST), expanding his threat to include strikes on key infrastructure such as power plants and bridges.

Trump also indicated he was unconcerned about potential legal implications tied to such actions.

Amid the rising rhetoric, António Guterres cautioned against targeting civilian infrastructure, reiterating that such attacks are prohibited under international law.

On the ground, hostilities intensified overnight.

Israel launched fresh airstrikes across Iran early Tuesday, while Iran retaliated with missile attacks targeting Israel and parts of the Gulf region.

At least 15 people were reported killed in strikes across Iranian cities, according to local media.

Iran also fired missiles toward Saudi Arabia, with authorities reporting that most were intercepted, though debris fell near energy facilities.

The attacks led to the temporary closure of the King Fahd Causeway, a vital link between Saudi Arabia and Bahrain.

In response to fears of further escalation, Iranian officials called on citizens to gather around critical infrastructure sites, including power plants, in an effort to deter potential strikes.

Meanwhile, Israel issued public warnings in Farsi advising Iranian civilians to avoid rail travel, signalling possible targeting of transportation networks.

Strikes were reported in areas around Tehran, including Shahriar and Pardis, where casualties were recorded.

International concern is mounting, with France also urging restraint.

Foreign Minister Jean-Noël Barrot warned that attacks on civilian and energy infrastructure could trigger a dangerous cycle of retaliation, with far-reaching consequences for regional stability and the global economy.

The conflict, which has severely disrupted shipping through the strategically vital Strait of Hormuz, a key route for global oil supplies, shows no immediate signs of de-escalation as both sides continue to exchange fire.