The president was expected to sign the official condolence book and attend a reception Sunday at Buckingham Palace hosted by King Charles III before attending the queen's funeral at Westminster Abbey on Monday.

Biden is among many world leaders traveling to the United Kingdom to honor Queen Elizabeth's long reign. Biden and first lady Jill Biden were greeted at the airport by U.K. Ambassador Jane Hartley, Lord Lieutenant of Essex Jennifer Tolhurst, and others.

After the queen's death, Biden issued a proclamation directing that all American flags be flown at half staff "as a mark of respect for the memory of Queen Elizabeth II" until sunset on the day of her interment. Before coming to London, he spoke with the king to offer his condolences and went to the British Embassy as well.

The queen died on Sept. 8 after a 70-year reign, sparking grief and mourning across the United Kingdom and around the world.

She had met multiple U.S. presidents, including, in more recent years, Donald Trump, Barack Obama, and George W. Bush. She met 13 of the past 14 American presidents, all except Lyndon Johnson and starting with Harry Truman in 1951 when she was still a princess.

The Bidens, who joined the queen for tea in June 2021, are due to arrive in London on Saturday evening.

On Sunday they are scheduled to pay respects to the late sovereign, whose coffin is lying in Westminster Hall. Afterward, they will sign an official condolence book before attending a reception hosted by King Charles.

The state funeral on Monday is to be attended by nearly 100 presidents and heads of government.

Biden, 79, has said the queen reminded him of his mother. The president is familiar with grief, having lost his adult son to cancer in 2015 and his wife and young daughter to a car accident decades ago.

The president will return to Washington on Monday after the funeral.