‘Australia is secure when Papua New Guinea is secure, and Papua New Guinea is secure when Australia is secure.’ So said Billy Joseph, PNG’s minister for defence, at the ASPI Defence Conference in June. This sentiment underpinned the intent of both governments this week to sign the Papua New Guinea-Australia Mutual Defence Treaty (the Pukpuk Treaty, named after the pidgin term for a crocodile). It contains ambitious measures to deepen the integration between the two nations’ defence forces and elevates their defence relationship to an alliance. It would mark the first such treaty by PNG with another country and would be Australia’s first since the 1950s. As our closest neighbour, PNG has occupied Australian strategic thought and invoked concerns about being a launch pad for threats to Australia since the 1800s.