Donald Trump has said the Duke of Sussex was "not speaking for the UK" when he called for the US to show "leadership" on Ukraine - comments which came days before King Charles was due to meet the president.
Speaking on a visit to Kyiv, and without mentioning Trump, Prince Harry said the US should "show that it can honour its international treaty obligations – not out of charity but out of its enduring role in global security and strategic stability".
Asked about the remarks, Trump said: "Prince Harry? How's he doing? How's his wife? Please give her my regards.
"I know one thing, Prince Harry is not speaking for the UK, that's for sure. I think I am speaking for the UK more than Prince Harry."
The US president added that he appreciates Prince Harry's advice "very much".
Prince Harry's unannounced trip to Ukraine came days after he left Australia, where he and wife Meghan, both no longer working royals, had visited in a private capacity.
"The United States has a singular role in this story. Not only because of its power, but because when Ukraine gave up nuclear weapons, America was part of the assurance that Ukraine's sovereignty and borders would be respected," Harry said.
The US president did not answer directly when asked if he would invite Harry to dinner during the state visit of King Charles III and Queen Camilla next week.
"He's a friend of mine. We're really looking forward to it. We've spoken and we're going to have a great time," Trump said about the King.
He added that the guests would be people who "love the UK", and that he too loved the UK, before running through a quick list of what he thought the country needed to do.
"I think they made a big mistake on energy. You should open up the North Sea in Aberdeen. You should open it up," he said.
"And the other thing is they've made a big mistake on immigration."
During his trip to Ukraine, Prince Harry travelled to the town of Bucha, north of Kyiv, where he flew an AI-powered drone as part of a demonstration of the latest demining technology by the Halo Trust - a landmine clearance charity.
Harry said: "When my mother visited Angola nearly thirty years ago, deminers carried out their work on their hands and knees to uncover hidden explosives. Now they're also using drones, AI and robots for greater precision and protection."
Diana visited Angola in 1997 as a guest of the International Red Cross, and went into a minefield alongside an expert from the trust.
Her trip to Angola, and another to Bosnia to meet victims who sustained injuries during that country's war in the 1990s, is credited with raising international attention about the issue of landmine use.
The King and Queen are due to meet Trump at the White House during their four-day visit to the US, which starts on Monday.
The trip comes during a tense period in US-UK relations, particularly on the question of British involvement in the Iran war.
The US president previously said he was "not happy" with the UK government's decision not to join offensive operations.
Trump has repeatedly publicly criticised Prime Minsiter Sir Keir Starmer, including describing him as "not Winston Churchill" in March following the government's refusal to allow US aircraft to use UK bases for its initial strikes on Iran.
However, the president has also said the King's visit to the US could "absolutely" help repair relations.
Responding to a question from BBC News, Trump described the King as a "fantastic man".
The BBC has approached Buckingham Palace and the Foreign Office for comment.
