Dozens of lawyers specializing in international law from major US universities have signed an open letter pointing out that US strikes on Iran may constitute war crimes after President Donald Trump this week reiterated his threats to hit Iranian power and desalination plants.

Trump said in a televised address Wednesday that the war would escalate if Tehran did not accept Washington’s terms, threatening strikes against Iran’s energy and oil infrastructure.

More than 100 international law experts in the United States — including some working at universities such as Yale, Harvard, Stanford and the University of California — pointed out in their letter published yesterday, Thursday, that the conduct of US forces and statements by senior US officials “raise serious concerns about violations of international humanitarian and human rights law, including possible war crimes.”

Their letter specifically referenced a comment Trump made in mid-March when he said the US might launch strikes against Iran “just for fun.” They also cited statements made by US Defense Secretary Pete Hegseth in early March, when he said the US does not fight “with stupid rules of engagement.”

The letter was published on the Just Security magazine website.

The experts expressed “grave concern about the strikes targeting schools, health facilities and homes,” referring specifically to the strike on the first day of the war, on February 28, against a girls’ school in Iran.

The US military indicated in March that it had assigned the investigation into the incident to an unnamed US general outside Centcom, after media reports revealed that a preliminary investigation concluded that US forces were likely responsible. The Iranian Red Crescent reported that 175 people were killed in the strike, including many schoolgirls.

The US president threatened on Wednesday to strike Iran “extremely hard”. “We’re going to hit them extremely hard in the next two to three weeks. We will send them back to the Stone Age where they belong,” he said.

An American Muslim rights advocacy group has denounced Trump’s wartime statements, including this latest threat, as aimed at “dehumanizing” Iranians.