French authorities carried out a special security exercise at Nice Airport on Sunday after receiving a threat of an attack with the deadly gas used by the Nazis at the Auschwitz extermination camp during World War Two. Airport officials said no flights were cancelled or delayed despite the exercise under which security was tightened and checked, a month before NATO defence ministers are due to arrive for a summit in Nice on France's Mediterranean coast. Nice city authorities said they arranged the exercise involving 350 military and civilians after a group called the Anti-Globalization Liberation Front sent a letter written...