The effort to negotiate and adopt a legally binding instrument to manage marine biodiversity beyond areas of national jurisdiction (BBNJ) implicates national security interests both directly and tangentially. First, negotiations for any agreement will contend with the long-standing concept that the oceans are reserved for “peaceful purposes.” The maritime powers will insist that the concept, which reflects customary law and the practice of virtually all states, does not demilitarize the oceans. Second, any BBNJ treaty must overcome two interrelated spatial issues: the geographic parameters of what constitutes “areas beyond national jurisdiction” when those maritime boundaries are often uncertain, and how measures to protect the environment interact with military activities in those areas. Naval powers will insist that requisite marine protected areas (MPAs) and associated protective measures do not diminish naval freedom of navigation and other military uses of the sea. Third, BBNJ negotiations will be compelled to address how a new treaty will relate to the United Nations Convention on the Law of the Sea (UNCLOS), a host of other treaties, and customary norms. Imperfect as the contemporary global order of the oceans is, major maritime powers and even middle powers will seek to protect it and resist efforts at radical change that may destabilize existing regimes in pursuit of an ephemeral gain for BBNJ. This strategic interest in international stability, while understandable, unintentionally creates inertia that is likely to frustrate the most progressive proponents of BBNJ. Fourth, more broadly, any treaty is likely to affect marine ecosystem services and perhaps marine genetic resources (MGR), which help propel the “blue economy” and undergird national security. We may expect most coastal states to continue to jealously protect their exclusive rights to the living and nonliving resources offshore, and even to propose expansion of those rights and jurisdiction to “adjacent areas.” The most developed states, for their part, are unlikely to agree to any text that diminishes their rights to intellectual property related to marine biotechnology, which is a strategic sector for bio-weapons research and defense. In short, states with advanced military capabilities, and major maritime powers in particular, are unlikely to support more than incremental change to the regimes reflected in UNCLOS.