This book reviews whether the existing framework in place can effectively address breaches in the context of Autonomous Weapons Systems (AWS). The work endeavors to map out the main gaps and some possible approaches to address them. Part I sets the ground. First, it provides a concept of AWS. Next, it discusses the accountability gap AWS generate and shows how the international community has put far more emphasis on individual responsibility rather than state responsibility. Part II analyzes the challenges AWS pose to the regime governing state responsibility under international law, as codified in the Draft Articles on State Responsibility (ARSIWA). In this regard, it discusses attribution, breach of an international obligation, tempus comissi delicti, multiple states involved in a breach, force majeure, assurance of non-repetition, issues related to damage, the human-machine interaction and its impacts on state´s responsibility, responsibility for not using AWS, weapons review and the duty of due diligence. Part III summarizes the challenges discussed in part II in thirteen issues of concern and presents possible paths de lege ferenda to address each of those issues, mainly a paradigm shift in attribution and strict liability, among seven other more specific proposals. The conclusion reached is that the current regime on the international responsibility of states is insufficient to deal with the new challenges AWS pose. De lege ferenda, the book argues for following the paths suggested in part III. It also reflects on parts II and III's findings and how many of AWS's challenges to state´s responsibility apply to other autonomous devices. Therefore, through the case study of AWS, this work also opens the broader discussion of the gaps in the international responsibility of states regarding autonomous device misdoings.