The 2013 Australian Defence White Paper categorically termed Australia's zone of strategic interest the Indo-Pacific, the first time any government has defined its region this way. This raises questions about what the Indo-Pacific means, whether it is a coherent strategic system, the provenance of the concept and its implications for Asian security as well as Australian policy. Indo-Pacific Asia can best be understood as an expansive definition of a maritime super-region centred on South-East Asia, arising principally from the emergence of China and India as outward-looking trading states and strategic actors. It is a strategic system insofar as it involves the intersecting interests of key powers such as China, India and the USA, although the Indo-Pacific subregions will retain their own dynamics too. It suits Australia's two-ocean geography and expanding links with Asia, including India. The concept is, however, not limited to an Australian perspective and increasingly reflects US, Indian, Japanese and Indonesian ways of seeing the region. It also reflects China's expanding interests in the Indian Ocean, suggesting that the Chinese debate may shift towards partial acceptance of Indo-Pacific constructs alongside Asia-Pacific and East Asian ones, despite suspicions about its association with the US rebalance to Asia. Questions about Australia's ability to implement an effective Indo-Pacific strategy must account for force posture, alliance ties and defence diplomacy, as well as constraints on force structure and spending.