Donald Trump has said that he is strongly considering leaving Nato over the lack of support shown for his attack on Iran.

The US president told The Telegraph that the military alliance was a “paper tiger” and that taking the US out of the bloc was now “beyond reconsideration”.

“I was never swayed by Nato. I always knew they were a paper tiger, and Putin knows that too, by the way,” he told the newspaper.

The president took aim at the UK, saying the country “doesn’t even have a navy”, after prime minister Sir Keir Starmer reaffirmed that Britain would not get “dragged in” to a conflict that was “not our war”.

Trump on Tuesday singled out Britain and France for a scathing dressing down over their reluctance to get involved in the war.

He wrote on social media that the US “won’t be there to help you any more, just like you weren’t there for us” and told allies they would have to “get your own oil”, following a report that he has told aides he would be willing to end the war without the reopening of the Strait of Hormuz.

The closure of the vital waterway is putting enormous pressure on Trump’s allies in Europe, who have come under fire from the Trump administration for not joining the US-Israel strikes on Iran.

The president told The Telegraph that he thought an allied response should be “automatic”. He said Washington had been there “automatically” in trying to mediate a ceasefire between Ukraine and Russia.

“Ukraine wasn’t our problem. It was a test, and we were there for them, and we would always have been there for them. They weren’t there for us,” he said.

Nato’s collective defence clause holds that an attack on one member should be treated as an attack on all, necessitating a response of some kind from all members. The Article 5 clause has only been invoked once, in response to the 9/11 attacks, which saw Nato members rally in aid of the US.

US Secretary of State Marco Rubio echoed Trump’s comments in an interview with Fox News late on Tuesday, saying the administration would “have to reexamine the value of Nato and that alliance for our country”.

“If Nato is just about us defending Europe if they’re attacked, but them denying us basing rights when we need them, that’s not a very good arrangement. That’s a hard one to stay engaged in,” he said.

British prime minister Sir Keir Starmer ruled out putting boots on the ground on Monday, after relaxing rules allowing the US to operate out of bases on British soil.

“Of course, we will defend British lives and British interests in the region, will stand by our allies in the Gulf region, but we’re not going to get dragged in,” he told an audience at Labour’s local election campaign launch in Wolverhampton.

YouGov shows 59 per cent of the British public oppose the conflict, while around 25 per cent support it. Just over half (52 per cent) believe Sir Keir is handling the relationship with Trump badly, however.

Only eight per cent of voters agree that the UK should join the US and Israel in “launching attacks on a wide range of targets in Iran”, according to a poll recorded on 4-5 March. Most (46 per cent) agree that the UK military should only be tasked with shooting down drones and defending civilian areas and UK military facilities.

Trump’s comments come just weeks after he threatened to annex Greenland, a territory of Nato ally Denmark. The president has repeatedly criticised Nato members over historically low defence spending. Nato spending rose 20 per cent year on year in 2025, according to the latest report.