This chapter examines the emergence of grey zone conflicts as the main mode of interaction between powerful states and non-state actors including armed groups, and the implications therein for international law and conflict management. It deals with regime theory and finds that democracies frequently experience democratic backsliding as a consequence of their efforts to counter the low-intensity hybrid tactics employed by their illiberal opponents and non-state allies. Traditional interpretations of non-state armed groups are those actors who operate outside state control, challenge the state’s monopoly on coercive force, and who are capable of preventing, blocking or endangering a humanitarian or conflict resolution initiative. According to the literature, non-state armed groups have been driven to conflict for a number of important reasons. One of the most important debates regarding grey zone conflict has focused on how non-democratic states conduct hybrid operations using non-state actors against their democratic adversaries and what democracies can do to respond to those actions.