The Queen is hosting Mr Trump and other Nato leaders tonight. Ahead of the reception, the US President and the First Lady met Charles and the Duchess of Cornwall for afternoon tea at Clarence House.
Camilla wore a red dress teamed with a black jacket.
Mrs Trump looked stylish in a yellow cape dress with purple heels.
Charles and Camilla greeted Mr and Mrs Trump, who arrived in the UK yesterday for the Nato summit, and they posed for pictures before moving to private quarters for tea.
They are all attending the reception at Buckingham Palace later.
It comes as Charles is taking on more responsibilities from the Queen.
The Trumps also had afternoon tea with Charles and Camilla during their state visit to the UK in June.
In an interview with ITV’s Good Morning Britain, Mr Trump claimed he was pressed on climate change by Charles.
“I did mention a number of things, I did say the United States right now has among the cleanest climates.”
Charles met other Nato leaders earlier, including Canadian Prime Minister Justin Trudeau, Prime Minister of Norway Erna Solberg and Italian Prime Minister Giuseppe Conte.
It comes as NHS workers and anti-war activists have led a protest targeting Mr Trump and Nato in central London.
Hundreds of protesters gathered in Trafalgar Square before marching towards Buckingham Palace.
Earlier today as the Nato summit kicked off, Mr Trump insisted the US wants “nothing to do with” the NHS following claims it could be used as a bargaining chip in post-Brexit trade talks.
Asked if the NHS should be on the table in trade talks between the UK and the US, he said: “No, not at all, I have nothing to do with it. Never even thought about it, honestly.
“I don’t even know where that rumour started.
“We have absolutely nothing to do with it and we wouldn’t want to if you handed it to us on a silver platter, we want nothing to do with it.”
Boris Johnson hit the campaign trail in the South West today ahead of the General Election.
The Prime Minister said he could “categorically rule out” that “any part of the NHS will be on the table in any trade negotiations”, adding that it included pharmaceuticals.
Mr Johnson said: “This is pure Loch Ness Monster, Bermuda Triangle stuff.”