Military artificial intelligence (AI)-enabled technology might still be in the relatively fledgling stages but the debate on how to regulate its use is already in full swing. Much of the discussion revolves around autonomous weapons systems (AWS) and the ‘responsibility gap’ they would ostensibly produce. This contribution argues that while some military AI technologies may indeed cause a range of conceptual hurdles in the realm of individual responsibility, they do not raise any unique issues under the law of state responsibility. The following analysis considers the latter regime and maps out crucial junctions in applying it to potential violations of the cornerstone of international humanitarian law (IHL) – the principle of distinction – resulting from the use of AI-enabled military technologies. It reveals that any challenges in ascribing responsibility in cases involving AWS would not be caused by the incorporation of AI, but stem from pre-existing systemic shortcomings of IHL and the unclear reverberations of mistakes thereunder. The article reiterates that state responsibility for the effects of AWS deployment is always retained through the commander's ultimate responsibility to authorise weapon deployment in accordance with IHL. It is proposed, however, that should the so-called fully autonomous weapon systems – that is, machine learning-based lethal systems that are capable of changing their own rules of operation beyond a predetermined framework – ever be fielded, it might be fairer to attribute their conduct to the fielding state, by conceptualising them as state agents, and treat them akin to state organs.

This article explores the conditions and modalities under which a state can incur responsibility in relation to violations of international law involving military applications of artificial intelligence (AI) technologies. While the question of how to attribute and allocate responsibility for wrongful conduct is one of the central contemporary challenges of AI, the perspective of state responsibility under international law remains relatively underexplored. Moreover, most scholarly and policy debates have focused on questions raised by autonomous weapons systems (AWS), without paying significant attention to issues raised by other potential applications of AI in the military domain. This article provides a comprehensive analysis of state responsibility in relation to military AI. It discusses state responsibility for the wrongful use of AI-enabled military technologies and the question of attribution of conduct, as well as state responsibility prior to deployment, for failure to ensure compliance of AI systems with international law at the stages of development or acquisition. Further, it analyses derived state responsibility, which may arise in relation to the conduct of other states or private actors.

The notion of meaningful human control (MHC) has gathered overwhelming consensus and interest in the autonomous weapons systems (AWS) debate. By shifting the focus of this debate to MHC, one sidesteps recalcitrant definitional issues about the autonomy of weapons systems and profitably moves the normative discussion forward. Some delegations participating in discussions at the Group of Governmental Experts on Lethal Autonomous Weapons Systems meetings endorsed the notion of MHC with the proviso that one size of human control does not fit all weapons systems and uses thereof. Building on this broad suggestion, we propose a “differentiated”—but also “principled” and “prudential”—framework for MHC over weapons systems. The need for a differentiated approach—namely, an approach acknowledging that the extent of normatively required human control depends on the kind of weapons systems used and contexts of their use—is supported by highlighting major drawbacks of proposed uniform solutions. Within the wide space of differentiated MHC profiles, distinctive ethical and legal reasons are offered for principled solutions that invariably assign to humans the following control roles: (1) “fail-safe actor,” contributing to preventing the weapon's action from resulting in indiscriminate attacks in breach of international humanitarian law; (2) “accountability attractor,” securing legal conditions for international criminal law (ICL) responsibility ascriptions; and (3) “moral agency enactor,” ensuring that decisions affecting the life, physical integrity, and property of people involved in armed conflicts be exclusively taken by moral agents, thereby alleviating the human dignity concerns associated with the autonomous performance of targeting decisions. And the prudential character of our framework is expressed by means of a rule, imposing by default the more stringent levels of human control on weapons targeting. The default rule is motivated by epistemic uncertainties about the behaviors of AWS. Designated exceptions to this rule are admitted only in the framework of an international agreement among states, which expresses the shared conviction that lower levels of human control suffice to preserve the fail-safe actor, accountability attractor, and moral agency enactor requirements on those explicitly listed exceptions. Finally, we maintain that this framework affords an appropriate normative basis for both national arms review policies and binding international regulations on human control of weapons systems.

Autonomous weapons systems (AWS) are emerging as key technologies of future warfare. So far, academic debate concentrates on the legal-ethical implications of AWS but these do not capture how AWS may shape norms through defining diverging standards of appropriateness in practice. In discussing AWS, the article formulates two critiques on constructivist models of norm emergence: first, constructivist approaches privilege the deliberative over the practical emergence of norms; and second, they overemphasise fundamental norms rather than also accounting for procedural norms, which we introduce in this article. Elaborating on these critiques allows us to respond to a significant gap in research: we examine how standards of procedural appropriateness emerging in the development and usage of AWS often contradict fundamental norms and public legitimacy expectations. Normative content may therefore be shaped procedurally, challenging conventional understandings of how norms are constructed and considered as relevant in International Relations. In this, we outline the contours of a research programme on the relationship of norms and AWS, arguing that AWS can have fundamental normative consequences by setting novel standards of appropriate action in international security policy.

This article presents an initial discussion of the political and legal challenges associated with weaponised technologies in three interconnected areas that may impinge upon the ability to protect civilian populations during peace and war and imperil international security: armed unmanned combat aerial vehicles (commonly known as drones); autonomous weapons systems (known as ‘killer robots’); and the potential militarisation of cyberspace, or its use as a weapon, and the operation of drones and killer robots in the cyber domain. Supporting the argument that the world is ‘facing new methods of warfare’ and that international security governance and law are not keeping up, the article provides an overview and interpretation of three technologies in connection with aspects of five branches of law: state responsibility, use of force, international humanitarian law, human rights law, and law of the commons. I argue therefore that ‘preventive security governance’ could be a strategy to curtail uncertainty in the preservation of stability and international order. I define ‘preventive security governance’ as the codification of specific or new global norms, arising from existing international law that will clarify expectations and universally agreed behaviour on a given issue-area. This is essential for a peaceful future for humanity and for international order and stability.

This article reconsiders the status and legality of both autonomous and remote weapons systems under international humanitarian law. Technologically advanced unmanned military systems are being introduced into the modern battlespace with insufficient recognition of their potential challenge to international humanitarian law. The article questions the understanding of both autonomous and remote weapons systems as ‘weapons’ and seeks to consider how their use may impact existing legal categories. Their use is then specifically situated to consider the legality of their deployment in certain contexts. Finally, the article raises the question of impunity for the use of both autonomous and remote weapons systems that arise from the inability to attribute responsibility for the harm they cause. It is imperative that law and policy are developed to govern the development and deployment of these advanced weapons systems to forestall these likely situations of impunity.