<p>Some proponents of a ban on Autonomous Weapon Systems (AWS) believe adopting these would lower the threshold for war, and is thus morally undesirable. This paper argues against that thesis. First, removing a single constraint on warmaking does not automatically make war more likely. Analysis of the causal input of other more potent restraints shows this holds true for just a fraction of potential conflicts. Secondly, AWS adoption would also impact other restraints on war in ways that are complex and unpredictable. Without a thorough analysis of these other impacts, AWS’ adoption impact on the incidence of war cannot be said to be significant enough to warrant action. Thirdly, war ethics does not aim to reduce the number of wars simpliciter, but to resist, deter, and thus reduce occurrence of unjustified aggression. Consequently lowering the threshold for defensive war, especially for wars of collective defense and/or humanitarian interventions, would be a good outcome, potentially offsetting a possible negative effect on the incidence of aggressive wars. Last but not least, states that already restrain themselves from aggressive warring by sufficiently robust alternative mechanisms cannot be required to eschew AWS adoption for that reason. Taken together, these arguments prove that the impact of AWS introduction on the incidence of war cannot be discerned through a priori philosophical analysis alone. Consequently ‘lower threshold for war’ argument cannot support calls for an AWS ban.</p>