Australian Prime Minister Tony Abbott delivers remarks at a national memorial service for the victims of Malaysia Airlines flight MH17 at St Patrick's Cathedral in Melbourne August 7, 2014. Australia held a national day of mourning on Thursday for its citizens killed in the downing of Malaysia Airlines Flight MH17 in Ukraine last month, even as Russia said it was ratcheting up its response to Western sanctions imposed over the disaster. REUTERS/Mark Dadswell (AUSTRALIA - Tags: TRANSPORT DISASTER POLITICS HEADSHOT TPX IMAGES OF THE DAY)