Buckingham Palace has paid tribute to the 2,977 victims of the September 11 terror attacks on the 25th anniversary.The Band of the Coldstream Guards performed the US national anthem in the forecourt of Buckingham Palace on Friday.The Duke and Duchess of Gloucester were joined by the United States Ambassador to the United Kingdom, Mr. Warren Stephens and his wife Harriet Stephens, as well as the Foreign Secretary Ed Miliband and Security Minister Dan Jarvis for a special Changing of the Guard ceremony to commemorate the 25th Anniversary of 9/11.