Trump’s remarks represent a dramatic volte-face on his earlier position, when he said the Prince would get no support from the White House if he won the election.
“I wouldn’t protect him,” he said. “He betrayed the Queen. That’s unforgivable. He would be on his own if it was down to me.”
He was also critical of the Joe Biden administration for resisting the push to open up the Prince’s immigration records.
“I think they have been too gracious to him after what he has done,” he said.
The Heritage Foundation, a US-based conservative think tank, has alleged the Duke may have lied about his illegal drug use on immigration records or otherwise been given preferential treatment in order to relocate to the US.
It argued he had waived his right to privacy when he divulged personal details in Spare.
The Duke revealed in his memoir, published in January 2023, that he had taken cocaine several times as a teenager and experimented with cannabis and mushrooms.
The Heritage Foundation brought a lawsuit against the Department of Homeland Security after it rejected a Freedom of Information Act request for access to the Duke’s records.
It questioned how the royal had been able to settle in the US after he had admitted illegal drug use, but Judge Carl J Nichols ruled “the public does not have a strong interest in disclosure of the Duke’s immigration records”.
The case was recently reopened on a technicality, raising the prospect Trump’s administration might take a different approach.
Last March, Trump hinted that he might be prepared to intervene in the case, telling GB News: “We’ll have to see if they know something about the drugs, and if he lied they’ll have to take appropriate action.”
Asked whether that meant Prince Harry “not staying in America”, he said: “Oh, I don’t know. You’ll have to tell me. You just have to tell me. You would have thought they would have known this a long time ago.”
There has been no love lost between Trump and the Sussexes.
Before marrying into the royal family, Meghan made her views about the politician known, describing him as “misogynistic” and “divisive”.
Then, ahead of the 2020 presidential election, the Duke and Duchess appeared to back former US president Joe Biden over Trump when they released a video message urging US voters to “reject hate speech, misinformation and online negativity”.
The Duchess described it as the “most important election of our lifetime”.
The couple toned down their rhetoric ahead of last year’s election in an apparent attempt to avoid a spat with Trump, who had said he was “no fan” of the Duchess.
However, Trump is a huge fan of the Royal family and tipped to become the first elected politician in modern history to be hosted for two state visits by the British monarch.
He has often spoken in glowing terms about the state visit he enjoyed with his wife Melania Trump and adult children in June 2019 during his first US presidency.
A documentary about his successful US election campaign last year saw Trump showing off a photo album of royal meetings, at one point calling King Charles a “really good person”.
Prince William’s November meeting with Trump in Paris was considered a diplomatic coup.
Some in the Foreign Office are said to see the Prince as the “secret weapon” in helping improve relations between a Starmer-led UK and Trump-led US in the years ahead.
Trump later described his 30-minute chat with the heir to the throne as “really wonderful” and joked that the future King was a “very handsome man”.
Sir Keir Starmer’s government is widely expected to use Mr Trump’s fascination with the monarchy to strike up a strong personal relationship that benefits the UK.
The Duke and Duchess arrived in Vancouver on Friday night for the Invictus Games and are staying at one of the city’s most expensive hotels.
At a behind-closed-doors welcoming reception for competitors, the Duchess introduced her husband and told the injured veterans: “You are his family.”
She said: “What you won’t have seen is all of the moments that have happened in the lead-up to these Games.
“All of the moments like the big rush in the morning – getting ready for school, packing the lunchboxes, making breakfast. My husband’s in all of that with us, and then he’ll be on his phone, and Archie will say, ‘Papa, why are you on your phone?’ And he’s like, ‘That’s Invictus. I’m getting ready for Invictus’.
“It means so much to him. You are his family, just as we are his family, and I hope you recognise how much of his heart he has poured into every single thing that has gotten all of you to this week, which is going to be spectacular. I just need you to know that.”