U.S. President Donald Trump inspects an honour guard during a welcoming ceremony at Buckingham Palace, London, June 3, 2019, on the first day of his three-day state visit to the U.K. [Photo: AFP/MANDEL NGAN]"

Britain's Queen Elizabeth II (R) shakes hands with U.S. President Donald Trump during a welcoming ceremony at Buckingham Palace, London, June 3, 2019, on the first day of the U.S. President and First Lady's three-day state visit to the U.K. [Photo: AFP/Victoria Jones]"

Britain's Queen Elizabeth II views a display of U.S. items in the Royal Collection with U.S. President Donald Trump and First Lady Melania Trump at Buckingham Palace, London, June 3, 2019, on the first day of their three-day state visit to the U.K. [Photo: AFP/Tolga AKMEN]"

US President Donald Trump (C) and First Lady Melania Trump (L) are shown around Westminster Abbey by the Dean of Westminster, John Hall, (R), London, June 3, 2019, on the first day of the U.S. President and First Lady's three-day state visit to the U.K. [Photo: AFP/HENRY NICHOLLS]"

Britain's Queen Elizabeth II (R) raises a glass with U.S. President Donald Trump during a state banquet in the main ballroom at Buckingham Palace, London, June 3, 2019, on the first day of the U.S. President and First Lady's three-day state visit to the U.K. [Photo: AFP/Dominic Lipinski]"