Prince Harry is said to be faced with a huge “Donald Trump challenge” after his impassioned speech in Ukraine, which sparked backlash from both Russia and the US. In a rare input on global matters, the King’s youngest son turned his attention to the US last week – although he did not mention Mr Trump by name – urging the “American leadership” to “honour its international treaty obligations” in its “enduring role in global security”.

The Duke of Sussex said: “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. This is a moment for American leadership, a moment for America, to 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.”

Harry’s lengthy, strong-worded statement could risk making things “uncomfortable” in California for him, according to a royal commentator.

Royal correspondent Richard Palmer claimed that Harry’s public display of support for Ukraine may make things challenging for him in the US from people who support Mr Trump.

He told the Mirror: “He sort of laid down a challenge for the US, and that won’t go down well with Trump at all

“The MAGA [Make America Great Again] movement does not like Harry and Meghan, so this will probably only make things worse in that sense. It may well be a little uncomfortable for Harry because of the visa issue.”

However, Mr Palmer praised the Duke for going to Ukraine himself, adding: “We haven't seen King Charles or Prince William go to Ukraine, so fair play to Harry.

“His remarks will be celebrated by President Zelenskyy and his aides, and probably be a useful boost for Ukraine at this time.”

Responding to Harry’s speech in Ukraine, Mr Trump told reporters: “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.” He added: “But I appreciate his advice very much.”

He went on to ask: “How’s he doing? How’s his wife? Please give her my regards.”