This chapter is concerned with the role of peacekeeping in wider normative processes and structures of world politics. At its inception, peacekeeping derived from a Westphalian conception of world order based on state sovereignty and non-intervention. This was exemplified by the first UN peacekeeping force, which was deployed in 1956 in the Sinai: peacekeepers were interposed between two conflicting states, and they abided by strict neutrality and non-use of force (except in self-defence). The blueprint changed after the end of the Cold War, when traditional peacekeeping gave way to missions that incorporated elements of a post-Westphalian conception of “liberal peace” based on democracy, human rights, and the rule of law.2 Peacekeepers thus received broad mandates, which often included statebuilding tasks, and they were expected to protect civilians in a proactive way, using all necessary means at their disposal. The new functions did not replace traditional peacekeeping principles, but they were juxtaposed with them. Indeed, peacekeeping as defined by the UN Department of Peacekeeping Operations (UNDPKO) still rests on the three basic principles of consent of the parties, impartiality, and non-use of force except in self-defence and in defence of the mandate.3