King Charles has written privately to Donald Trump after the former US president survived an assassination attempt, Buckingham Palace says.
It is understood the British monarch's message was in keeping with UK Prime Minister Keir Starmer's conversation with Trump, in which he condemned the violence.
Charles also expressed his condolences for the victims and their families and wished the former president and those injured a quick recovery.
The message was delivered on Sunday via the UK embassy in Washington.
Buckingham Palace said the contents of the correspondence would be kept private.
In 2019, Charles, then Prince of Wales, hosted Trump and his wife Melania for afternoon tea at Clarence House with the then-Duchess of Cornwall during a NATO summit in London.
Trump was also feted with a state banquet, hosted by the late Queen, during a state visit to the UK earlier the same year.
The Republican presidential candidate, who was targeted by a gunman at a campaign rally in Butler, Pennsylvania, said he wants to "bring the country together" in the wake of the attack.
Trump said on his Truth Social media platform that a bullet had "pierced" his ear before he was dragged to the ground by Secret Service agents.
One person at the rally was killed — former fire chief Corey Comperatore — and two other spectators were critically injured, authorities said.
The gunman, 20-year-old nursing home employee and registered Republican Thomas Matthew Crooks, was shot dead by the Secret Service.
It was the most serious attempt to assassinate a US president or presidential candidate since Ronald Reagan was shot in 1981.
