Since the early years of the twenty-first century, a number of key regional governments have consciously chosen to alter the way they talk about the region, and have now largely shifted from using the ‘Asia-Pacific’ to the ‘Indo-Pacific’ construct. But after three decades of utilising the ‘Asia-Pacific’ concept, why has this been the case and how might this shift in geographical conceptualisation alter the strategic framework of the region? This paper argues that the ‘Indo-Pacific’ is a regional reconceptualisation utilised by Japan, Australia, India and the USA to address deficiencies in Asia’s maritime security and institutional architecture, which are being simultaneously influenced by a more assertive Chinese posture and waning U.S. influence. Additionally, the Indo-Pacific concept has developed in tandem with a transformation in the regional security architecture. The utilisation of maritime minilateralism between Japan, India, Australia and the USA supplements Asia’s bilateral American alliances, with an array of trilateral security dialogues or ‘security triangles’. The Asia-Pacific to Indo-Pacific shift is really an instance of an emerging minilateral security regionalism, rather than the predominant forms of bilateral and multilateral security and economic regionalism that have dominated Asia in recent decades.