King Charles reportedly sent a surprising message to Donald Trump after his slur against British troops.
Speaking at last week’s World Economic Forum summit in Davos, Switzerland, Trump angered the UK after claiming the US's Nato allies did not pull their weight during two decades of the war in Afghanistan.
The President said at the time: "We’ve never needed them. We’ve never really asked anything of them. You know, they’ll say they sent some troops to Afghanistan, or this or that.
"And they did. They stayed a little back, a little off the front lines."
A total of 457 British service personnel were killed in the Afghanistan war, with hundreds of others left injured, many of whom with life-changing injuries.
Trump's comments sparked immediate outrage, with Prince Harry - who served two tours in Afghanistan during his time in the army - stating: "I made lifelong friends there. I lost friends there. Thousands of lives were changed for ever.
"Mothers and fathers buried sons and daughters. Children were left without a parent. Families are left carrying the cost.
"Those sacrifices deserve to be spoken about truthfully and with respect, as we all remain united and loyal to the defence of diplomacy and peace."
Following the backlash, Trump eventually changed his outlook, praising the UK for fighting in the war with "tremendous heart and soul", and calling British service personnel "among the greatest of all warriors," before adding: "We love you all and always will."
Trump's online backtrack allegedly came after the White House was informed of King Charles's unease at his comments.
A British official told The Sun: "You would always expect our Commander-in-Chief to defend the Armed Forces’ proud record of service and sacrifice."
A source added: "It was made very clear that the King’s concern over the hurt had been caused by the comments, whether inadvertent or not."
Trump is known to be a vocal admirer of the British Royal Family, having previously called King Charles "a great gentleman and a great King" during his historic second State visit last September.
King Charles III and Queen Camilla are expected to travel to the US in April to meet with Trump as part of the 250th anniversary of US Independence.
The royal family traditionally keep their political views guarded, and rarely make any comment publicly.
Backtracking on his comments, Trump had written on Truth Social: "The great and very brave soldiers of the United Kingdom will always be with the United States of America!
"In Afghanistan, 457 died, many were badly injured, and they were among the greatest of all warriors.
"It’s a bond too strong to ever be broken. The UK Military, with tremendous Heart and Soul, is second to none (except for the USA!). We love you all, and always will! President Donald J Trump."