President Donald Trump threatened on Wednesday to bomb Iran “hard” again as a fragile peace agreement between the US and Tehran began to unravel.

Only a month after signing an interim peace deal with Iran, Trump launched an extraordinary tirade against the country at the Nato summit in Ankara, calling the regime “scum” and saying “I don’t want to deal with them anymore”.

His comments came a day after US forces launched the most significant wave of strikes on Iranian targets since the deal was agreed in response to attacks on three ships transiting the Strait of Hormuz. Tehran retaliated with strikes on US air bases in Qatar and Kuwait.

In a sign that the latest strikes could spiral into a return to full conflict, Trump told reporters on Wednesday: “I’ll give a little warning: We’re going to hit them hard tonight.”

Defence secretary Pete Hegseth, who is accompanying Trump at the summit, is reported to have cancelled a trip to Israel following the comments, according to The Jerusalem Post.

Despite the US leader taking several jabs at Nato, alliance secretary general Mark Rutte defended Trump’s decision to launch strikes on Iran.

Dozens of Iranian small boats were hit as state media reported strikes on Kharg Island, Qeshm Island, and in the port cities of Sirik and Bandar Abbas.

“When you have a ceasefire and Iran is basically violating the ceasefire, I think it is totally crucial that the US forcefully react,” Rutte told reporters.

Asked by journalists why he refused to criticise Trump for his comments insulting Spain and Denmark, Rutte replied: “What I always do is acknowledge when praise is due.”

French president Emmanuel Macron also backed the US decision to hit Iran, saying that he believed Iranian strikes on US bases in the Gulf violated the interim accord and that Iran had been mistaken to carry them out, according to Reuters.

But Macron said he understood that meetings as part of a 60-day ceasefire between the two sides would continue.

US Central Command defended the strikes, saying that Iran’s “demonstrated aggression was unwarranted, dangerous and a clear violation of the ceasefire”, referring to the three tankers, including a Qatari vessel, that were hit in the Strait of Hormuz.

The IRGC said it had targeted 85 facilities and a reaper drone in response to attacks but has denied responsibility for the strikes on ships.

Iran’s parliamentary speaker Mohammed Bagher Ghalibaf accused the US of violations of the MOU, writing on X: “The era of bullying and extortion is over. It leads nowhere. We don’t fold.”

However, Qatar blamed it for attacking the vessels, including its LNG tanker Al Rekayyat, which reported being hit by a drone that caused a fire in its engine room. No casualties were reported following the incident.

Meanwhile, defence companies from Nato member states are reported to have agreed to more than $50bn in defence procurement and industrial agreements as allies sought to demonstrate their commitment to bolstering military spending.

The summit has also been overshadowed by Trump’s renewed interest in taking over Greenland, prompting Danish prime minister Mette Frederiksen to vow to defend “every inch” of it.

His press conference alongside Ukrainian president Volodymyr Zelensky also raised eyebrows after he confused Iran for Japan, referring to the “Islamic Republic of Japan”. He also appeared to confuse Zelensky for Russian president Vladimir Putin.

After repeated pleas by Zelensky for US-made interceptors, Trump appeared to confirm he would provide Ukraine with a license and said that further talks on anti-ballistic missiles would ensue.

“We’re going to give a license to you to make Patriots. That’s pretty cool. This way, you can’t complain that we’re not giving them enough,” he said.

“It’s a defensive weapon, which I like better than an offensive weapon.”

Patriot interceptors are the only weapon that are able to shoot down ballistic projectiles, due to the high velocity and steep flight path of the weapons.