Britain’s Prime Minister David Cameron arrives in Downing Street in central London

Britain’s Prime Minister David Cameron arrives in Downing Street in central London August 20, 2014. Cameron interrupted his holiday and returned to London on Wednesday after Islamic State released a video that appeared to show the beheading of a man identified as a U.S. journalist, featuring comments by a man with a British accent. REUTERS/Toby Melville (BRITAIN – Tags: MILITARY POLITICS)