National security is one of the most contentious topics in public policy and politics and one of the most important for the twenty-first century. Since the terrorist attacks of 11 September 2001, security and defence have undergone such unprecedented overhauls that even recently implemented policies require reexamination. In this second edition of Security and Defence in the Terrorist Era, Elinor Sloan provides a significantly revised and updated analysis of developments in Canadian and American security and defence policy and notes where there are weaknesses that call for improvement. The author argues that since the Second World War Canada has assumed that potential threats will come from overseas rather than from within its borders. Security and Defence in the Terrorist Era shows that Canada's safety depends upon paying equal attention to threats at home and insists that we must consider the effect of climate change on the Arctic as seriously as terrorist threats and ballistic missile defence.