An armed police officer keeps guard as British soldiers march out of Buckingham Palace after the changing of the guard ceremony in London, Thursday, May 23, 2013. Britain was coming to terms with an apparent return of terrorism to its capital Thursday as new information emerged about the butchering of a British soldier near an army barracks in Woolwich by suspected Islamic radicals. (AP Photo/Kirsty Wigglesworth)

An armed police officer keeps guard as British soldiers march out of Buckingham Palace after the changing of the guard ceremony in London, Thursday, May 23, 2013. Britain was coming to terms with an apparent return of terrorism to its capital Thursday as new information emerged about the butchering of a British soldier near an army barracks in Woolwich by suspected Islamic radicals. (AP Photo/Kirsty Wigglesworth)