New South Wales police officers guard a post near the fenced-off site of the siege at the Lindt cafe in Martin Place, Sydney, December 17, 2014. Tough new national security laws failed to prevent a deadly hostage crisis in the heart of Sydney this week, Australian Prime Minister Tony Abbott said on Wednesday, raising questions about the usefulness of such measures. REUTERS/Jason Reed (AUSTRALIA - Tags: CRIME LAW POLITICS CIVIL UNREST)