King Charles discussed the attack at the White House Correspondent's dinner during some small talk with President Trump, a lip reader has claimed.
On the first day of their state visit to the US, the King and Queen Camilla attended the White House, where they enjoyed tea with Trump and First Lady Melania.
The visit comes just days after Cole Tomas Allen, 31, stormed the Washington Hilton hotel, with Trump and Melania rushed to safety by secret service agents along with other senior members of the administration. Allen has been charged with attempting to assassinate the president.
Forensic lipreader Nicola Hickling observed the interactions between Trump and the King for the Sun.
According to Hickling, Trump raised both Saturday's shooting and his recent discussions with Vladimir Putin - with Charles responding: “We will discuss that later".
Meeting on the White House’s South Lawn, Trump and Melania welcomed their guests, warmly shaking hands and embracing the royal couple before posing for photographers for nearly a minute.
Trump then attempted to make conversation with the King. Hickling told the Sun, the president said: "This shooting..." before the King interjected.
Charles is alleged to have said: "I'd rather not stand about here too long. I feel I shouldn't be here."
Trump then is believed ot have said: “Are you okay? It’s not a good thing… I wasn’t prepared, but now I am prepared.”
Trump then changes the subject, stating: “So right now, I am talking to Putin… he wants war,” before Charles responds firmly: "We will discuss that later".
Trump continues: "I've got a feeling… if he did what he said, he will wipe out the population," before Charles again deflects the conversation, saying “Another time.”
The group then leave the lawn for a private tea together in the Green Room on the State Floor which lasted for about 45 minutes, with conversation moving to a more lighthearted subject en route.
President Trump offered his visitors a tour of his White House ballroom project, saying: "You can see right through there, right the way through to the ballroom. Would you like to see?"
The King replied: "I'm sure you shall show us."
Following their tea, the King and Queen attended a garden party attended by hundreds of guests, including former Olympian Tom Daley and numerous senior members of Trump's administration.
Buckingham Palace confirmed that “minor adjustments” would be made to the trip following the shooting, but that otherwise the state visit would “proceed as planned”, with Trump promising that Charles and Camilla would be “really safe”.
The State visit has been much anticipated, amid a growing rift between the US and UK governments over the Iran war.
Trump has been particularly critical of Prime Minister Keir Starmer in recent weeks over his lack of support of the US military attacks on Iran, but has insisted this will not affect the royal visit.
White House spokesperson Anna Kelly said: “President Trump has always had great respect for King Charles, and their relationship was further strengthened by the President’s historic visit to the United Kingdom last year.
“The President looks forward to a special visit by Their Majesties, which will include a beautiful state dinner and multiple events throughout the week.”
The visit will span across four days, with Trump hosting the royals at a lavish State Dinner at the White House.
The King is also scheduled to address a joint session of Congress on Capitol Hill which will raise “challenges” facing the UK and US.
Charles and Camilla will then go to New York City and visit the 9/11 Memorial at One World Trade Centre, before travelling to Virginia, where they will visit a national park and attend community events and cultural performances.
