The proposition that Australia faces an 'arc of instability' to its north has been an important feature of the Australian strategic debate in the early twenty-first century. Prompted by worries in the late 1990s over Indonesia's future and East Timor's uncertain path to independence, the 'arc' metaphor also encapsulated growing Australian concerns about the political cohesiveness of Melanesian polities, including Papua New Guinea and Solomon Islands. While tending to overlook the divergent experiences of countries within its expanding boundaries, the 'arc' fed from Australia's historical requirement for a secure archipelagic screen. As such it has became an important weapon in the debate over whether the locus of Australia's strategic priorities should be increasingly global in the 'war on terror' period or remain closer to home in the immediate region. The 'arc of instability' metaphor was consequently adopted by leading Australian Labor Party politicians to argue that the Howard Coalition government was neglecting South Pacific security challenges. It became less prominent following the Howard government's greater activism in the South Pacific, signalled by Australia's leadership of the East Timor intervention in 2003. But its prominence returned in 2006 with the unrest in both Honiara and Dili. In overall terms, the 'arc of instability' discussion has helped direct Australian strategic and political attention to the immediate neighbourhood. But it has not provided specific policy guidance on what should be done to address the instabilities it includes.