King Charles III’s visit to the United States ended with what has been branded a ‘diplomatic blunder’ at Arlington National Cemetery . ​ The King and Queen Camilla, who arrived in the U.S. Monday , were at the Virginia memorial Thursday to pay their respects at the Tomb of the Unknown Soldier. ​However the Union flag was incorrectly flown upside down during the parade at the cemetery.​ “Rather a diplomatic gaff (sic) by the Americans here,” S ky News correspondent Mark Stone remarked on X . “The Union flag is upside down at the Arlington Cemetery event.” A Union flag was flown upside down during King Charles III and Queen Camilla’s visit to Arlington National Cemetery (Getty) In the half nearest the flagpole, the Union flag’s wider diagonal white stripe must be above the red diagonal stripe, according to the Flag Institute . “It is most improper to fly the flag upside down,” the institute says. ​ During the event, the King and Queen were met by U.S.…