This paper takes a somewhat negative approach to the goal of building collaboration to address transnational maritime security issues in the Indo-Pacific. It does not make the case that seeking improvements in cooperation is unreasonable, unworkable or simply not worthwhile - only that there exist sound reasons why strict limits to maritime security cooperation pertain in many circumstances. Some of those reasons may be due to temporary contexts, such as short-term political factors. Others may relate to problems inherent in the particular issue in question, and yet others may be deeply structural and, indeed, intractable. My argument therefore is structured in the following way. First, it addresses the intractable, underlying problems that make progress in maritime security cooperation so difficult. Second, it briefly addresses certain transnational maritime security issues, explaining why cooperation to deal with some threats is much easier than for others.