King Charles and U.S. President Joe Biden arrive to meet participants of the Climate Finance Mobilisation forum in the Green Drawing Room at Windsor Castle, Berkshire, during President Biden's visit to the UK. Picture date: Monday, July 10, 2023. Andrew Matthews/Pool via REUTERS

Larry the cat is removed from the red carpet ahead of U.S. President Joe Biden's arrival at 10 Downing Street in London, Britain, July 10, 2023. REUTERS/Hollie Adams TPX IMAGES OF THE DAY

U.S. President Joe Biden is welcomed by Britain's King Charles at Windsor Castle in Windsor, Britain, July 10, 2023. REUTERS/Kevin Lamarque

Marine One, carrying U.S. President Joe Biden, leaves Windsor Castle in Windsor, Britain July 10, 2023. REUTERS/Kevin Lamarque

British Prime Minister Rishi Sunak and U.S. President Joe Biden react after their meeting at 10 Downing Street in London, Britain, July 10, 2023. REUTERS/Hollie Adams TPX IMAGES OF THE DAY

U.S. President Joe Biden meets Britain's King Charles at Windsor Castle in Windsor, Britain, July 10, 2023. REUTERS/Kevin Lamarque

U.S. President Joe Biden meets with British Prime Minister Rishi Sunak at 10 Downing Street in London, Britain, July 10, 2023. REUTERS/Kevin Lamarque

U.S. President Joe Biden participates in a ceremonial arrival and inspection of the honour guard with Britain's King Charles at Windsor Castle in Windsor, Britain, July 10, 2023. REUTERS/Kevin Lamarque TPX IMAGES OF THE DAY

King Charles and President of the United States, Joe Biden take part in a welcome ceremony at Windsor Castle on July 10, 2023, in Windsor, England. Sgt Donald C Todd/Handout via REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY.

People gather behind metal barriers as U.S. President Joe Biden meets with British Prime Minister Rishi Sunak at 10 Downing Street in London, Britain, July 10, 2023. REUTERS/Kevin Lamarque

U.S. President Joe Biden walks to Marine One at Windsor Castle, in Windsor, Britain, July 10, 2023. REUTERS/Kevin Lamarque

The President of the United States, Joe Biden shakes hands with King Charles in the Quadrangle at Windsor Castle on July 10, 2023 in Windsor, England. Chris Jackson/Pool via REUTERS