Recent years have seen growing attention for the use of AI technologies in warfare, which has been rapidly advancing. This chapter explores in what ways such military AI technologies might contribute to Global Catastrophic Risks (GCR). After reviewing the GCR field’s limited previous engagement with military AI, and giving an overview of recent advances in military AI, this chapter focuses on two risk scenarios that have been proposed. First, we discuss arguments around the use of swarms of Lethal Autonomous Weapons Systems, and suggest that while these systems are concerning, they appear not yet likely to be a GCR in the near-term, on the basis of current and anticipated production limits and costs which make these systems still uncompetitive with extant systems for mass destruction. Second, we delve into the intersection of military AI and nuclear weapons, which we argue has a significantly higher GCR potential. We review historical debates over when, where, and why nuclear weapons could lead to GCR, along with recent geopolitical developments that could raise these risks further. We then outline six ways in which the use of AI systems in-, around-, or against- nuclear weapons and their command infrastructures could increase the likelihood of nuclear escalation and global catastrophe. The chapter concludes with suggestions for a research agenda that can gain a more comprehensive and multidisciplinary understanding of the potential risks from military AI, both today and in the future.