Bart L. Smit Duijzentkunst recently received his PhD in international law from the University of Cambridge. He will be teaching international law at the Fletcher School of Law and Diplomacy, Tufts University, in the 2015 fall semester.] When, in December 2013, the United Nations Mission in South Sudan (UNMISS) opened its gates to thousands of civilians fleeing violence in the wake of an alleged coup, it also opened a new chapter on the UN’s commitment to the protection of civilians. Two decades earlier UN troops had received vague orders to protect “safe areas” in Bosnia and Rwanda—with disastrous consequences. Today UNMISS is explicitly authorised to use “all necessary means” to protect civilians. Yet while the language of UN mandates has evolved, so have developments on the ground. UN policy-makers originally envisioned protection of civilians measures as short-term, localised interventions to ensure the physical safety of persons in acute emergency situations. In South Sudan, however, 18 months after the outbreak of hostilities almost 140,000 people continue to reside in so-called “protection of civilians sites” across the country. As a result, UNMISS peacekeepers are not simply called upon to protect against external threats, but also to maintain public safety and security within protection of civilians sites. But does their mandate cover these activities? This post briefly discusses the evolution of peacekeeping mandates before offering some reflections on UNMISS’ authority. Protection of civilians mandates emerged in UN Security Council practice on the eve of the new millennium. In “traditional” mandates, the protection of civilians had been an afterthought, the fortuitous consequence of other peacekeeping objectives. For example, the mandate of UNPROFOR, operating in the Balkans in the mid 1990s, merely called upon the mission to deter attacks on so-called “safe areas”, to monitor cease-fires and to promote the withdrawal of military and paramilitary units from these areas. UNPROFOR could only take “all necessary measures”, including the use of force, in self-defence. Similarly, when UNAMIR in Rwanda was authorised to establish “secure humanitarian areas” in 1994, the UN Security Council recognised that the mission might be required to take action in self-defence to protect the areas, but did not explicitly authorise it to use force to do so. Propelled by the failures in Bosnia and Rwanda, and encouraged by the emerging idea that the international community held a “responsibility to protect” vulnerable populations, in 1999 the UN Security Council started to explore the protection of civilians as an objective of peacekeeping. It began passing dedicated resolutions and included protection of civilians clauses in operational mandates. These “robust” mandates reflect a recognition by the Security Council that impartiality of UN peacekeeping operations “is not the same as neutrality or equal treatment of all parties in all cases for all time” and that in certain circumstances “peacekeepers may not only be operationally justified in using force but morally compelled to do so.” In the same year, the UN Security Council vested certain missions with far-reaching administrative powers. UNMIK in Kosovo and UNTAET in East Timor were tasked to provide administrative functions while developing domestic institutions. In line with their “executive” mandates, these missions were empowered to draft local laws, implement domestic policies and administer justice, including arresting and sentencing alleged criminals, until these powers were transferred to local governments (in 2008 and 2002 respectively). With these differences between traditional, robust and executive mandates in mind, let’s return to the situation of UNMISS. Following South Sudan’s independence on 9 July 2011, UNMISS’ initial mandate focussed on state-building and conflict resolution efforts; the protection of civilians was buried deep in its sub-clauses. These political ambitions went up in flames with the outbreak of violence on 15 December 2013, when an alleged coup triggered a civil war between Government forces, led by President Salva Kiir, and the Sudan People’s Liberation Movement/Army – In Opposition (SPLM/A-IO), headed by former vice-President Riek Machar. In light of the persistent fighting and the massive influx of internally displaced persons and refugees onto UNMISS premises, the UN Security Council revised UNMISS’ mandate in November 2014 to make the protection of civilians its top priority. The new, robust mandate removes references to “imminent” threats, simply authorising UNMISS to “use all necessary means” to “protect civilians under threat of physical violence, irrespective of the source of such violence”. While housing, food and sanitation are principally provided by humanitarian organisations, UNMISS is in charge of “maintain[ing] public safety and security within and of UNMISS protection of civilians sites”. This is not the first time that the UN has provided shelter to civilians on its premises: from East Timor to Palestine, over the last decades civilians have flocked to UN bases in the face of violence. The UN has developed various policies to deal with these situations, which range from setting out general principles to providing specific guidelines on civilians seeking protection at UNMISS sites (the latter drafted prior to December 2013). All these documents stress the exceptional and temporary nature of these measures: they speak of protection in terms of hours or days, not weeks or months. Yet as the conflict in South Sudan persists and peace remains elusive, what might have seemed a temporary measure at first has turned into a prolonged situation with few prospects of resolution.