US President Barack Obama (2nd L) and first lady Michelle Obama (2nd R) pose with Queen Elizabeth (L) and Prince Phillip, Duke of Edinburgh (R) before a State Dinner at Buckingham Palace in London May 24, 2011.[Photo/Agencies]

US President Barack Obama (L) and first lady Michelle Obama (R) talk to Britain's Prince William (2nd L) and Catherine, Duchess of Cambridge at Buckingham Palace, in London May 24, 2011.[Photo/Agencies]

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