The King and Queen have had tea with Donald Trump after arriving for their US state visit – here's what the royals have been up to so far and what's to come later today.
It's the first state visit to the US by a British monarch since 2007, when Queen Elizabeth II met with George W Bush.
As it happened: How King's first day in US unfolded
The King will address Congress on Tuesday - and will use his speech to say the story of the UK and US since America's independence is "one of the greatest alliances in human history".
While we don't know the exact timings, Buckingham Palace said the speech is expected to last for around 20 minutes.
It will be only the second time a British monarch has addressed the US Congress, after Queen Elizabeth II in 1991.
Charles will also reflect on how "time and again, our two countries have always found ways to come together" and how defence, intelligence and security ties "are measured not in years but in decades", a palace spokesperson said.
His address to both houses is likely to be seen as acknowledging tensions between Mr Trump and Prime Minister Sir Keir Starmer, who have clashed over the American leader's war against Iran.
The trip got under way on Monday when King Charles and Queen Camilla stepped out from their plane at Joint Base Andrews and walked down the stairs to a red carpet before shaking hands with officials waiting to greet them.
Charles and Camilla were both then gifted with a bouquet before departing the airfield in a car. They also stopped to listen to a military band playing the national anthems of the UK and the US.
Next up, for the royals' first official appointment, was a meeting with Donald Trump and Melania Trump at the White House.
They were welcomed on the South Lawn by the president and first lady, with the two couples shaking hands and embracing each other.
The royals then posed for photos before heading inside the US president's residence, while Charles and Trump could be seen having extended conversations.
Before their arrival, it was agreed that the King would meet with Mr Trump behind closed doors.
We have no details on what they discussed, but we do have pictures of the Trumps showing the royals around the White House - and having tea.
The King and Queen also attended a garden party at the British embassy in Washington.
Sky's royal correspondent Laura Bundock noted during the trip that it was a "gentle start", adding: "He has never been hosted by a president like Donald Trump.
"We know Trump loves the Royal Family, but we also know that Trump can't keep quiet at times. He is an unpredictable president."
What's next on the agenda?
The King and Queen will also attend a state dinner at the White House and - looking further ahead - will travel to New York to commemorate the 25th anniversary of the September 11 terrorist attacks.
They will also mark 250 years of US independence at a "block party" in Virginia, and - on a much lighter occasion - the Queen will give a specially made toy of the Winnie the Pooh character Roo to the New York Public Library to complete a set of the beloved characters in one of the institution's collections.
(c) Sky News 2026: The King in the US: The best of day one - and what's up next
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