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(p.1) Introduction
Composing Peace
Vincenzo BoveChiara RuffaAndrea Ruggeri
Oxford University Press

Abstract and Keywords

This introductory chapter starts by presenting the core focus of the book—which is about diversity of mission composition within UN peace operations—and its objectives. The book asks two questions. The first is conceptual and descriptive: what do we mean by mission composition in a peacekeeping mission? The introduction highlights the importance of focusing on diversity of mission composition against the backdrop of recent trends in UN peacekeeping. It presents the analytical framework and the four key dimensions of mission composition: field diversity, top leadership diversity, vertical leadership distance, and horizontal distance. The second question of the book is explanatory: does mission composition in United Nations peacekeeping matter? The Introduction also presents the scope of the explanatory part of the research, where we set to explore how each dimension of mission composition affects peacekeeping effectiveness. The remainder of the Introduction presents the mixed-method design adopted in the book and its strategies of data collection as well as the contributions and limitations of the book. It concludes by outlining the book structure.

Keywords:   trends in UN peacekeeping, mission composition, diversity, UN peacekeeping diversity, mission composition, peacekeeping effectiveness, quantitative analysis, case study research

General X has just stepped down from a senior position in the United Nations (UN) mission in Mali where fifty-six nationalities compose the Blue Helmet’s force on the ground.1 When we met General X for a Swedish fika in June 2019, he told us that ‘UN peacekeeping boils down to having all these countries from all over the world doing peacekeeping together and how together they can get their job done. Diversity can be good or bad’.2 Whether good or bad, diversity within and between UN peacekeeping3 missions is a fact: in 2018 alone, the UN deployed approximately 90,000 soldiers from 124 different countries. Moreover, diversity within UN peacekeeping missions is increasing. Since the end of the Cold War, peacekeeping missions have become both larger and more diverse. Does this increasing diversity make peacekeeping missions more effective? The vast literature on peace operations provides little guidance on this question.

This is a book about the diversity of mission composition within UN peace operations. It asks two inter-related questions. The first is conceptual and descriptive: what do we mean by mission composition in a peacekeeping mission? The second is explanatory: does mission composition in United Nations peacekeeping matter? To answer the first question, we develop an analytical framework and identify four key dimensions of mission composition and for each dimension we explore the issue of diversity. The first is field diversity, that is the diversity among the Blue Helmets deployed. For instance, where do the Blue Helmets come from? Does the mission consist of soldiers from two countries or from a multitude? The second is top leadership diversity. Top leadership diversity refers to the diversity between the positions of Force Commander (FC) and the Special Representative of the Secretary-General (SRSG). For example, is the Force Commander Swedish and the SRSG Indian? (p.2) The third is the vertical leadership distance, diversity between Force Commander and the peacekeepers. Does the Force Commander lead Blue Helmets of her/his own nationality or Blue Helmets from culturally, economically, or linguistically distant countries? The fourth is the distance between Blue Helmets and the local population: horizontal distance. Do the peacekeepers and the local population speak the same language? Are they culturally similar?

To answer the second question—does mission composition in United Nations peacekeeping matter?—we investigate how each dimension of mission composition affects levels of violence against civilians and the number of battle-related deaths. We do so in two complementary ways. First, we explore, using case studies, a set of mechanisms of peacekeeping effectiveness that may explain the relation between mission’s diversity and conflict reduction. Second we estimate the statistical relationship between each dimension of diversity of mission composition and peacekeeping effectiveness. We consider a mission effective if it reduces civilian and battle deaths. Second, in particular, we build on prominent extant theories of peacekeeping, focusing on the ability of a mission to exercise deterrence, reduce information asymmetries and influence conflict actors, and ask how the diversity of mission composition affects these theories. For instance, high field diversity—or a diverse group of Blue Helmets—may increase the range of the mission’s capacities, enhancing peacekeepers’ ability to exercise deterrence, decrease information asymmetries, and persuade local actors. At the same time, highly diverse Blue Helmets may lead to cross-cultural miscommunication, undermining the information-gathering capabilities of the missions. Similarly, a highly diverse pair of Force Commander and Special Representative of the Secretary-General, top leadership diversity, may enhance or hinder peacekeeping effectiveness. In terms of vertical leadership distance, having a Force Commander exercising command over a diverse set of peacekeepers may enhance the ability of the mission to signal its commitment to maintaining peace. Yet, it may also create severe coordination and authority issues leading to adverse outcomes for local populations. Finally, in terms of horizontal distance, Blue Helmets that come from culturally distant countries may signal the international community’s commitment. This commitment signalling may be positive, but it may also hinder the flow of information between the local population and the Blue Helmets or the capacity of the mission to fully understand the situation and thus make the local population less collaborative.

We answer our research questions by combining quantitative and qualitative methods. For each dimension of mission composition, we use quantitative methods to test the relation between mission composition and peacekeeping (p.3) effectiveness. Specifically, we use panel data for all UN peacekeeping missions since the end of the Cold War to estimate the correlation between the independent variables—the four dimensions of mission composition—and the dependent variable, peacekeeping effectiveness, measured as the capacity to save civilians’ lives and reduce levels of fighting between belligerents. We complement this quantitative analysis with three qualitative case studies in order to identify the causal mechanisms linking mission composition with peacekeeping effectiveness. We examine the UN missions in Lebanon, in Mali, and in the Central African Republic.

Our research reveals several key findings. High diversity in mission composition might improve peacekeeping effectiveness. However, the type of diversity matters. First, we find that field diversity has a positive effect: the higher the internal diversity of UN peacekeepers, the fewer civilian casualties within a conflict. Second, in terms of top leadership diversity (SRSG and FC), diversity can help mitigate civilian victimization and battle-deaths. Even though our case studies suggest that both negative and positive pathways could be at play, the quantitative analysis shows that, overall, top leadership diversity can be beneficial for mission effectiveness. Third, when it comes to vertical distance, the diversity between Force Commander and troops on the ground, our qualitative material suggests that both positive and negative pathways on an operation’s effectiveness are possible. However, our quantitative material indicates that this dimension matters mostly by protecting civilians from victimization rather than resolving the fighting between belligerents. Holding all constant, missions with more Blue Helmets from the same country of the Force Commander experience lower monthly deaths of civilian, whereas high linguistic barriers between the military leadership and the troopers might jeopardize civilians’ protection. Fourth, peacekeepers with less horizontal distance with the local population are better able to keep the peace. We find that greater geographic and cultural distances correspond to higher levels of violence against civilians and higher numbers of battle-related deaths. Institutional and economic differences have the opposite effects, reducing the violence against civilians and battle-related deaths, although these results are less robust.

In this introductory chapter, we begin by outlining how diversity in mission composition became crucial in recent trends of peacekeeping operations. Second, we discuss the gaps in existing peacekeeping literature. Third, we introduce our analytical framework and, fourth, discuss the research design and methods we use for answering our questions. Fifth, we reflect upon the contribution and the scope conditions of our argument. Finally, we present the structure of the book.

(p.4) I.1 On Diversity in Mission Composition

Peacekeeping missions are complex endeavours. Over the past thirty years, UN peacekeeping missions have undergone substantive changes including the diversity of mission composition. Since the end of the Cold War, peacekeeping missions have witnessed an increase in the number of peacekeeping troops deployed; an increase in the number of countries supplying peacekeepers; an increase in the average number of troop-contributing countries per mission; and a change in the pool of countries from which the UN can draw troops. In practice, peacekeeping operations have become bigger, more complex, and more diverse.

Of the seventy UN peacekeeping missions launched since 1948, the majority of missions were launched after the end of the Cold War. During the entire Cold War period, the UN launched just eighteen missions. Since 1990, the UN has launched more than fifty. Between 1989 and 1994 alone, the UN Security Council authorized twenty new peacekeeping operations, increasing the number of peacekeepers from 11,000 to 75,000. Crucially, UN peacekeeping missions and mandates have also expanded to include the implementation and enforcement of peace agreements in war-torn societies. Peacekeeping missions have transformed from mere observers into active enforcers of UN mandates, including approaches that extend beyond military presence. This shift from observer to active participant in conflicts has required launching missions that were larger, more robust, and more complex.

The evolution of UN peacekeeping missions has been more reactive than proactive. The UN’s legal framework to coordinate peacekeeping missions was originally developed to intervene in war between states. However, most contemporary conflicts feature wars within the states, where the domestic institutions have usually collapsed or are in the process of collapsing. The changes in both the scope and mandates of UN peacekeeping missions illustrate the organization’s cumulative—and non-linear—response to cyclical crises and self-critical evaluations (see the Brahimi Report, Capstone Doctrine, and the HIPPO Report4) rather than a planned long-term strategy. However, the historical expansion of UN peacekeeping missions in the post-Cold War era is often underappreciated by both the international community and International Relations scholars.

(p.5) Figure I.1 illustrates the overall number of UN peacekeepers deployed (trend line), and the overall number of countries contributing to UN peacekeeping forces (equal sized bins) between 1991 and 2017. Since the end of the Cold War, there have been two intertwined and unique increases: the number of peacekeepers in term of ‘size of deployment’ and the number of countries contributing to UN missions through their national armies. In 1991, there were approximately fifty nations contributing less than 20,000 troops to peace missions. These numbers sharply increased during peacekeeping operations in the Balkans, Rwanda, and Somalia. Despite a considerable drop in the number of peacekeepers in the late 1990s, since 1999 there was a notable resurgence. The UN launched new missions with mandates to utilize force in order to protect civilians, a sharp break from the pre-Cold War era when peacekeepers were only permitted to use force in self-defence. The UN may not have a permanent army, but, taken together, its deployment of military forces abroad is second only to the United States military. In 2017, about 100,000 Blue Helmets from more than 120 states were deployed across fourteen UN peacekeeping missions.


Figure I.1 Countries contributing and number of Blue Helmets

Although the UN has also increasingly deployed police officers alongside military personnel (Figure I.2), the size of the military personnel (UN troops, left-hand Y-axis in Figure I.2) represents the largest share of personnel on the ground. Therefore, this book focuses on UN troops because (p.6) their composition has rarely been studied systematically, despite playing such a crucial role in peacekeeping missions.5


Figure I.2 Number of UN troops and UN police officers over time

Perhaps most importantly, there is a large variation in UN peacekeeping missions in terms of the number of Blue Helmets deployed, as well as large variations in the degree of diversity across missions and, over time, within missions. Figure I.3 shows the average number of countries contributing to the largest UN missions (with at least 1,000 troops deployed). The United Nations Mission in South Sudan (UNMISS) has more than forty active troop contributors but both the missions in Angola or Timor-Leste have fewer than ten. Having too many contributing countries could create organizational problems, and a lack of skills complementarity. To illustrate, in July 2016, in (p.7) Juba (South Sudan) three days of intense fighting resulted in the death of many civilians, the deaths of two UNMISS peacekeepers, and threatened a fragile peace agreement. An internal investigation suggested that the heterogeneity of national contingents within UNMISS in terms of training, language, and military practices, could partially explain the disaster.6


Figure I.3 Top twenty missions by average number of contributing countries, 1990–2017

Figure I.4 shows the variation in the average number of donor countries per mission over time. An increase of contributing countries and the number of Blue Helmets over time, showed in Figure I.1, could be interpreted as a mere expansion of supply triggered by a broader UN engagement. However, this increase could have occurred without an increase of troop-contributing countries to each mission. In fact, in the last two decades, there has been a notable increase in the average number of troops per missions, with a maximum of twenty countries in 2017, and a minimum of three in 1999. We expect that variations in the level of diversity across missions could, all else equal, affect peacekeeping effectiveness.


Figure I.4 Average number of troop-contributing countries per mission

In addition to the historical change in both numbers of peacekeepers and contributing countries, there has also been a major geographical shift of troop (p.8) contributors to UN peacekeeping missions. Figure I.5 shows that the top twenty contributors in 1991 were mostly from European or North American countries. For example, in 1994, France was contributing more than 8,000 soldiers, the US more than 4,000, and the UK nearly 3,000 troops for peacekeeping missions. Today, Italy is the only European country among the top (p.9) twenty troop-contributing countries. France now contributes 739 soldiers, the UK 662, and the US only forty-nine. In the 1990s Western peacekeepers experienced a number of casualties in Rwanda, the Balkans, and Somalia. UN missions with more demanding rules of engagement or perceived as risky or morally unjustified have generated domestic pressure and consequently national caveats on deployment of forces. One decade later, the wars in Afghanistan and Iraq increased the pressure on Western countries to contribute more troops to those conflicts rather than to UN peacekeeping missions. Yet, also in North Atlantic Treaty Organization (NATO) missions’ domestic reservations have influenced Western countries’ willingness, and sometimes ability, to participate in peace missions.


Figure I.5 Top twenty contributors of troops to UN peacekeeping in 1991

As the contributions of Western countries declined, countries from the so-called ‘Global South’ began to recognize the benefits of participating in peacekeeping missions. Peacekeeping helps improve the regional standing of an emerging country, illustrating their responsibility and commitment to regional peace and security. The increase in troop contributions from the ‘Global South’ can also be attributed to security concerns. Most conflicts occur in less-developed regions. Peacekeeping missions can help prevent conflict spillover into surrounding areas and help contain refugee flows (Beardsley 2011; Beardsley and Gleditsch 2015). There are also economic benefits. Less-developed economies have a relatively large number of military personnel with low remuneration. The UN pays each soldier just over $1,400 a month while on duty. This amount may constitute a considerable share of a less-developed state’s military spending (Bove and Elia 2011). Finally, peacekeeping provides valuable training opportunities to less-advanced militaries in an international environment and the possibility to cultivate important partnerships. It also exposes national troops to a variety of collaborations and experiences (e.g. Bove and Elia 2011). Figure I.6 shows the change in the top twenty troop contributors in 2017, with top contributors now mainly from emerging and less-developed economies.7


Figure I.6 Top twenty contributors of troops to UN peacekeeping in 2017

In summary, since the end of the Cold War, UN peace missions have witnessed an increase in the number of peacekeeping troops deployed in each operation, an increase in the number of countries supplying peacekeepers, an increase in the average number of troop-contributing countries per mission, and a change in the pool of countries from which the UN can draw troops, particularly from the ‘Global South’. Taken together, these empirical changes suggest that rather than only the size of UN missions (Hultman (p.10) et al. 2013, 2014; Ruggeri et al. 2013), mission diversity may impact peacekeeping effectiveness. Troops and leaders from different national armies and societies come with complementary skills but also different practices and norms. This diversity could facilitate the conflict resolution process but also jeopardize it. Blue Helmets coming from faraway, or nearby, countries could interact differently with local populations and influence civilian protection. Yet, diversity of mission composition and its effects have never been studied systematically.

I.2 Research Gaps

We build on the burgeoning literature on peacekeeping and advance it by focusing on a previously neglected variable—diversity of mission composition—and by revising the mechanisms driving peacekeeping effectiveness.

I.2.1 Does Peacekeeping Keep the Peace? Yes, But …

Peacekeeping missions, especially UN missions, produce more durable peace (Fortna 2004, 2008; Fortna and Howard 2008; Gilligan and Sergenti 2008), produce geographically contained conflicts comparatively, shorter episodes of (p.11) local violence (Ruggeri et al. 2016b), improve the odds of peacebuilding success (Doyle and Sambanis 2000), and, over the long term, lower the likelihood of genocide within a conflict (Kathman and Wood 2011). While peacekeeping keeps and maintains peace, the conditions under which it is kept vary. Gilligan and Sergenti’s conclusions (2008) find peacekeepers to be more effective at maintaining peace than creating it. For instance, the effect of international intervention on mass killings appears conditional on whether the mission directly challenges and engages the perpetrators. While this finding suggests that only some missions reduce large-scale civilian killings, Melander (2009) finds that, after controlling for unobservable factors leading to deployment, peacekeeping does have a clear preventive effect on mass killings. Conversely, Kathman and Wood (2011) find that third party intervention can trigger more intense genocides and politicides in the months following the deployment of peacekeeping missions but, over time, there is a significant decrease in violence if the intervention is perceived as impartial. Notwithstanding different understandings of the concept of effectiveness, most authors have focused on ‘negative peace’, namely the absence of violence between belligerents and against civilians (Di Salvatore and Ruggeri 2017). While we acknowledge the limitations, we follow this approach given the lack of systematic knowledge on the effects of mission diversity. But what drives peacekeeping effectiveness?

I.2.2 Drivers of Peacekeeping Effectiveness: Mandates, Troops, and … ?

Peacekeeping literature identifies mission mandates and troop numbers as crucial variables to peacekeeping effectiveness. The key mechanisms of peacekeeping effectiveness are identified as deterrence and the reduction of information asymmetries. For instance, Doyle and Sambanis (2006) make a distinction between observer, traditional, multidimensional, and enforcement peacekeeping missions and posit that each has a different impact on two outcomes: ending violence and building peace. Traditional missions that encompass military deployment for interposition between belligerents, have no impact on these two outcomes, whereas multidimensional missions have a beneficial effect on participatory peace and tend to shorten conflicts. Enforcement is also effective in reducing violence, but it does not contribute significantly to peacebuilding. Fortna (2004) used the same categories of peacekeeping missions to determine the impact on the peace duration. She (p.12) finds that traditional missions have the strongest deterrence capacity and reduce the likelihood of conflict recurrence. Deterrence capacity diminishes in observer and multidimensional missions. Counterintuitively, however, Fortna finds that enforcement missions are not associated with more durable peace. More recent studies measuring the size of deployment and the type of deployed personnel have further supported these results: large deployments of peacekeeping troops have consistently beneficial impacts on all conflict outcomes (Hultman et al. 2013, 2014; Ruggeri et al. 2016b). Even in post-conflict environments, larger deployments of peacekeepers appear to lower civilian victimization (Kathman and Wood 2016). Peacekeeper observers and police seem to have no relevant impact on post-conflict peace. Other studies have also shown that the most successful missions have robust mandates (Beardsley and Gleditsch 2015; Hultman 2010; Kreps 2010). One notable exception is peacebuilding, which does not seem to be affected by the actual number of deployed personnel (Doyle and Sambanis 2000). These studies have overwhelmingly considered mandates and troops deployed at the mission level. However, we suspect that diversity within a mission might have an important impact on peacekeeping effectiveness.

I.2.3 Missing in Action: Diversity of Mission Composition

Recent quantitative work has adopted a more disaggregated approach that examines the local level. This disaggregated analysis presents a different set of findings. At the local level, Ruggeri et al. (2016b) find that peacekeepers shorten conflict episodes, but the empirical results on the capacity to deter local conflict onset are inconclusive. Using a similar, subnational research design, Fjelde et al. (2019) find that sizeable local deployment of peacekeepers decreases local civilian victimization. However, this work does not include an examination of the diversity of mission composition as a variable.

A limited number of recent works have begun to include mission diversity as a variable. Bove and Ruggeri (2016) published the first quantitative analysis of mission composition in relation to mission effectiveness. Building on these findings, Haass and Ansorg (2018) find that the mission composition of military capabilities matters, particularly the troop quality. Similarly, Goldring and Hendricks (2018) demonstrate how mission composition affects relations with local populations. However, despite the clear historical shifts in both the (p.13) size and composition of UN peacekeeping missions, there is currently no systematic understanding of what is meant by mission composition and its theoretical implications. To be fair, qualitative research on UN peacekeeping has highlighted the importance of some specific dimensions of mission composition (Bellamy and Williams 2013). For instance, qualitative scholars have been very instructive in assessing the effectiveness of the role of the local actors in driving the effectiveness of UN peacekeeping missions (Autesserre 2010; Howard 2007; Pouligny 2006). Several authors have noted the importance of alternative mechanisms within missions (Howard 2007, 2019), the procedure and functions in UN missions (Whalan 2013), the disaggregation of actors and micro dynamics (Autesserre 2014b), the relations of missions with local populations and contextual norms (Rubinstein 2008), and the military cultures and the perceptions among peacekeepers (Ruffa 2014, 2018a). Yet, the qualitative literature has never studied diversity of mission composition as a variable. In this book, we aim to fill three main gaps. First, we bring to the fore a new explanatory variable: diversity of mission composition. Second, we revise established mechanisms of peacekeeping effectiveness. Third, we evaluate the effect of diversity of mission composition on peacekeeping effectiveness, focusing on ‘negative peace’. We now introduce our analytical framework and our argument. Our main goal is to conceptualize, theorize, and empirically evaluate if and how diversity of UN mission composition matters.

I.3 Our Analytical Framework and Our Argument

I.3.1 Components of Mission Composition

When looking at UN missions with different components and relative compositions, four key dimensions and possible interactions have to be studied. Two important dimensions pertain to troops on the ground and two to leadership. Diversity of troops on the ground is key because troops are the core units tasked with mandate implementation and are interacting with the local population. Leadership is equally key as individuals in crucial positions can influence the outcomes of peace operations. This is especially true when mandates are more open to interpretation by the peacekeeping leadership. Each mission usually has two senior leadership positions: The Special Representative of the Secretary-General (civilian head) and a Force (p.14) Commander (military head).8 Striking variations persist in the nationalities of these leaders. For instance, in the UN mission in the Central African Republic, since its inception in 2014, the UN’s leadership has been mostly African. In the South Sudan mission, the civilian leadership has been European (Norway and Denmark), while the military leadership has been African (Nigeria, Ghana, and Ethiopia). It is reasonable to expect that differences between mission leadership and national contingents are also relevant for improving a mission’s capacity to bolster peace. A productive and trustworthy interaction between leaders and troops is essential for the success of an operation, yet differences—in terms of culture, norms, and training—between leaders and Blue Helmets can jeopardize a mission’s capacity. Therefore, we also analyse how the vertical distance between the Blue Helmets and the Force Commander impacts on mission effectiveness. Overall, we focus on four dimensions of mission composition. The first component relates to the peacekeepers at the tactical–operational level, tasked with the actual implementation of the mandate; the second pertains to the top mission leadership, that is the relationship between Force Commander and Special Representative of the Secretary-General; the third entails the relationship between mission leadership and the peacekeepers; and the fourth focuses on how Blue Helmets relate to the local population.

In this book, we measure diversity of mission composition according to the nationalities of both the troops and leadership of a mission.9 In order to avoid aggregation fallacy, we take into account the variation of military, linguistic, religious, and cultural diversity that exist within a mission. We operationalize diversity as distance between two analytical units. More specifically, distance is how much an analytical unit differs from another in respect to specified social dimensions. As a pre-theory step in our research process, we disaggregate composition into its internal and external dimensions. We understand internal dimensions as those components of mission composition that depict internal dynamics of the mission. We identify three internal components of mission diversity. First, diversity within peacekeeping troops, labelled field diversity. Second, diversity within mission leadership, labelled top leadership diversity. Third, diversity between the Blue Helmets deployed and the top (p.15) military leadership of a mission, the Force Commander, labelled vertical distance. In terms of field diversity, we consider the countries of origin of peacekeepers as the identifying characteristic. Thus, missions with a high degree of diversity have Blue Helmets from many different countries, whereas missions with soldiers from only a handful of countries have a low degree of diversity.10 For example, vertical distance will be small when troops and Force Commander belong to countries with similar characteristics, whereas missions with soldiers and Force Commander stemming from distant societies display high levels of distance. These distances may be also based on cultural or geographical differences and can have important consequences for the operational capabilities of a mission.

In terms of external dimension, we consider the distance between UN troops and the local population of a country affected by a conflict. We need to consider how composition can affect interactions with the local population, hence population will be an analytical unit as well. In this fourth dimension, we investigate the heterogeneity of a mission in relation to the local population, which we label horizontal distance, using weighted cultural and social distances.

I.3.2 Mechanisms

We now turn to the mechanisms that might influence peacekeeping effectiveness. Theories and explanatory mechanisms on peacekeeping operations remain tethered to rationalist approaches, focusing on the resolution of commitment problems and mitigating information asymmetry. These rationalist explanations primarily focus on the military costs of peacekeeping missions and if peacekeeping missions ‘work’. Such theoretical models often underplay the role of norms, cultures, perceptions, and ideas of peacekeepers deployed. As a part of developing our theoretical framework, we summarize the existing mechanisms within the peacekeeping literature based on the central issues of conflict resolution: asymmetric information and commitment problems (Fearon 1995; Kydd 2010; Schelling 1960). Previous studies by-and-large focused on two specific mechanisms of resolution that we label informative fungibility and muscular deterrence. Both (p.16) of these mechanisms imply that it is the mere presence of a UN peacekeeping mission or its deployment size that determines mission effectiveness. We build on these mechanisms and present four new mechanisms where the presence and size of UN mission are not enough to explain performances in the field: informative trust, informative communicability, resolve deterrence, and skilled persuasion. Variation in mission composition may affect how Blue Helmets can gather information, hence we argue that assuming information is always fungible is not possible. Hence, local population’s trust of the mission could be essential to collecting information (informative trust) and, therefore, who is part of a mission and not just how many are part of the mission could be a critical factor to build and sustain this trust. However, Blue Helmets and UN missions also need to be able to communicate what information they require and to understand the context in which local populations are providing information (informative communicability). Again, this form of informative capacity assumes that who is deployed matters. Therefore, in line with extant theories of peacekeeping, we agree that information asymmetry is a major barrier to conflict resolution, which peacekeepers play a central role in rebalancing. However, information is not always fungible. Information is gathered and understood according to who is deployed, hence the centrality of mission composition. Moreover, we argue that previous research largely assumes a specific form of deterrence: muscular deterrence. The main assumption is that local parties are deterred from committing wrongdoing based on the sizeable deployment and possible high costs that the mission can impose. We do not argue against deterrence as a mechanism per se,11 however we add another form of deterrence to our analysis that has less to do with the size of Blue Helmets deployment. We argue that composition and diversity of nationalities in a mission could be an effective signalling device for the resolve of the international community and, in turn, deter local actors from wrongdoing (resolve deterrence). Finally, we add to the classic issues highlighted by rationalist conflict resolution work—informative asymmetry and commitment problem—a mechanism based on nonmaterial power that affects the preferences of the actors involved as well as their intentions. We argue that persuasion is a crucial nonmaterial form of power (Howard 2019). Persuasion is enabled by skills such as mediation and communication, as well as by norms including risk propensity, situational awareness, and adaptability. Persuasion can modify local actors’ incentives (p.17) and, in turn, their actions. Hence, mission composition may also affect a mission’s capacity for skilled persuasion. Overall, instead of focusing on ‘if’ a mission is present and its size, these mechanisms require information on who the peacekeepers are, who their leaders are, how they are combined together, and whom they interact with. In sum, we argue that each of the four dimensions of mission composition, via the four mechanisms identified, influences peacekeeping effectiveness, both in terms of protecting civilians from atrocities and reducing battle-deaths. In Chapter 1, we summarize the core argument of the book and relative mechanisms. The following section outlines our methodology for answering our research questions.

I.4 Research Design and Methods

The core objective of this book is to test the impact of mission composition, at both leadership and organizational level, on peacekeeping effectiveness and unpack the causal mechanisms at play. To achieve this, we propose an integrated, comprehensive, and innovative design that combines quantitative and qualitative methods. We employ statistical methods to investigate the correlation between mission composition and performances using a large-N dataset with monthly data on peacekeeping deployments and levels of violence for thirty-three peacekeeping host-countries between 1991 and 2017.12 Therefore, our quantitative analysis is based on a cross-missions time series where our unit of analysis is the mission-month. This approach allows us to study and empirically leverage both variations between missions and within missions. Within our data, we have created original indices that operationalize different forms of diversity that capture the variation of mission composition. This book project has also gathered original data on the political and military leadership of UN peacekeeping missions. We collected monthly data on the UN Special Representative of the Secretary-General, defined here as the civilian head or the political leader, and the mission Force Commander, defined as the military leader, for each UN peacekeeping mission since 1991. In collecting (p.18) this data, we have extended Bove, Ruggeri, and Zwetsloot’s (2017) dataset on leadership in peacekeeping operations, which only covered a limited number of missions. Oddly enough, the UN does not provide systematic data on core figures of UN mission leadership and there are no other systematic quantitative analyses of leadership in UN peacekeeping missions.

I.4.1 Integrating Qualitative and Quantitative Methods

A range of disciplines in social science, such as political science, sociology, and psychology, has independently investigated peace operations using a variety of approaches. At the same time, there has been widespread debate within many of the social sciences regarding the relative merits of quantitative and qualitative methodologies for this type of research. In the current academic literature, this debate has created a methodological divide between qualitative case studies and large-N quantitative approaches to the study of conflict resolution. Most of the peacekeeping scholars view the two approaches as separate and based on alternative views of the world, with few adopting a mixed methodology strategy in their research. This divide has had a negative impact on theory development, preventing progress in the sense of cumulative knowledge, and has limited the development of new concepts and tools that can inform the study of peace operations. We attempt to bridge this divide by complementing the quantitative approach with case study methods to evaluate the mechanisms linking mission composition and peacekeeping effectiveness. The integration of qualitative methods is crucial in this research. First, qualitative methods allow us to examine the causal mechanisms by presenting a set of illustrative pathway cases. We delved into case study research, as opposed to limiting ourselves to illustrative examples that might prevent us from capturing broader phenomena. For each case study, we strived to combine case complexity and detect observable implications for key steps of the causal mechanisms. We present the findings of the qualitative approach first (Bryman 2007; Koivu and Hinze 2017). The reasoning behind this is to gauge and probe inductively the potential ‘pathways’ connecting the mechanisms at play. Broadly speaking, for each dimension of mission composition, we inductively explore the pathways that may connect diversity of mission composition with peacekeeping effectiveness. In most cases, we find divergent pathways: in one set of pathways, diversity in the specific dimension of mission composition, we focus on leads to an increase in peacekeeping effectiveness; (p.19) in a second set of pathways diversity leads to a decrease in peacekeeping effectiveness. We then turn to the large-N quantitative analysis to get a sense of which of the two pathways prevails. In this respect, our understanding of mechanism attempts to adhere to Gerring’s warning against a ‘mechanismic’—that is, mechanism-centric—approach to causal mechanism and, also, against a dogmatic view of it (Gerring 2010, 1499). Given the complexity of the empirical realities we examine, our understanding of mechanisms is one of ‘pathway or process by which an effect is produced’ (Gerring 2010, 1500). We acknowledge that while we strive to capture causal mechanisms, we are not testing them but probing their plausibility (George and Bennett 2005). We attempt to maximize the validity of our findings through in-depth empirical work and strategic case selection.

We opted for a strategic selection of cases based on their characteristics. Our challenge is that ‘the same causal mechanism may have opposite effects on an outcome depending on the triggers of the context of an event’ (Elster, 1998 cit. in Gerring, 2010, 1511). In each empirical chapter, we try to understand the conditions, triggers, or context through which a pathway may lead to an increase or a decrease of peacekeeping effectiveness. This also means that we are unable to fully capture each step of the causal chain at play. Instead, it is about the process linking the independent variable to the dependent variable (Elster 1989, 1–3). A further discussion of our understanding of mechanisms is presented in Chapter 1.

I.4.2 Case Selection

We opted for three pathway cases, in which we evaluate each of our four dimensions of mission composition. Pathway cases are used for elucidating causal mechanisms (Gerring 2009, 2006; Levy 2008). But as Gerring rightly points out ‘although all case studies presumably shed light on causal mechanisms, not all cases are equally transparent’ (2008, 664). We follow Gerring’s advice as we selected cases with ‘uniquely penetrating insight into causal mechanisms’ (2007, 238–9). However, unlike Gerring, we use our cases for theory development and we conduct our case studies prior to our cross-case analysis, as is common in political science and sociology (Barnes and Weller 2017).13 Following Weller and Barnes’s guidance, the first criterion for (p.20) selecting those cases is ‘the expected relationship between X1/Y, which is the degree to which cases are expected to feature the relationship of interest between X1 and Y’ (2017, 1009). The second criterion is ‘variation in case characteristics or the extent to which the cases are likely to feature differences in characteristics that can facilitate hypothesis generation’ (Barnes and Weller 2017, 1099).

We selected three diverse cases with varying levels of diversity in mission composition, different mandate provisions, and varying use of force conditions. We did so to ensure that similar detected mechanisms were to be found across a set of diverse missions and diverse types of mission composition. The cases we selected for qualitative examination are: the United Nations Interim Force in Lebanon (UNIFIL II), the United Nations Multidimensional Integrated Stabilization Mission in Mali (MINUSMA), and the United Nations Multidimensional Integrated Stabilization Mission in the Central African Republic (MINUSCA). These three cases were selected for three reasons. First, these missions comprise both traditional peacekeeping and the most innovative kinds of peacekeeping missions deployed, thereby allowing us to probe the plausibility of those mechanisms in a wide range of cases. While UNIFIL II is a traditional peacekeeping mission, MINUSMA and MINUSCA are ambitious, integrated, and multidimensional operations and their mandates foresee more tasks. Second, these cases display high levels of diversity among different dimensions, thereby making it possible to observe pathways. At the same time, the kind of diversity observed across all four dimensions is different: while UNIFIL II displays high polarization in terms of nationalities represented, MINUSCA mirrors mainly religious fractionalization.14 This configuration makes it particularly relevant for theory development. While a case with low diversity would have been good for inferential leverage, for pathway purposes, these cases are better suited. Third, these are ongoing operations, which allow us to study and capture contemporary issues and also interview peacekeepers deployed so as to make it more likely to capture the ongoing causal pathways. The downside of this is of course that we are unable to ultimately evaluate their long-run effectiveness, but we compensate for this through the large-N analyses.

(p.21) I.4.3 Strategies of Qualitative Data Collection

For each case, we rely on three main bodies of qualitative data. The first is a dataset on all three cases that we created solely based on recently published, secondary sources. The second is a dataset of case narratives that Ruffa utilized for her work on UNIFIL II (Ruffa 2018a). The third is original material collected for this project, comprising of fifteen interviews with peacekeepers deployed in the field or returned veterans, including one former SRSG, two former Force Commanders, one Deputy Force Commander, one Special Envoy, two Sector Commanders, and eight staff officers. Interviews were semi-structured and conducted in person or via videoconference, lasting between thirty minutes and ninety minutes. The interviews were intended to capture instances of causal pathways at different levels of analysis. The script for the interviews focuses on all four dimensions of diversity in mission composition and its effects, but also allowed the interviewee to make adjustments and elaborate on aspects of the phenomenon they deemed particularly important. The interview procedures have been approved by relevant authorities on ethical vetting and anonymity has been preserved when required (see the Qualitative Appendix for a full list of interviewees and interview scripts). Following recent trends to make qualitative research more transparent, we strived to be as precise as possible in terms of referencing (Barnes and Weller 2017; Moravcsik 2010) and we provide further detail in our Qualitative Appendix so as to allow other researchers to verify and consider how we have made inferences from our qualitative material (Moravcsik 2014).

We are aware of one fundamental selection bias in our qualitative empirical material. As one of our interviewees, a recently returned peacekeeper from MINUSMA, told us ‘you guys are going to find out much more about negative examples than about positive ones’.15 Indeed, negative reporting about failed cooperation are likely to be over-represented in our material, both because it is much more likely to be reported in the media and because it is much more likely to be narrated. This motivated us to conduct those fifteen in-depth qualitative interviews in an attempt to balance out this selection bias. While we try to be as alert about this bias as possible, we are aware that it is difficult to address. However, the quantitative component of this book should address the issue and evaluate the net effect of diversity of mission composition.

(p.22) I.5 What This Book Does and Does Not Do: Contributions and Scope Conditions

I.5.1 Contributions

This book makes four key contributions to the peacekeeping literature. First, current literature overlooks the role of the military in its assessment of peacekeeping missions. Research does not differentiate between UN peacekeeping troops and UN peacekeeping mission’s leadership. There is also an overemphasis on the number of peacekeepers deployed over the composition of these peacekeepers. This book challenges the assumption that more peacekeepers translate to greater success by examining the impact of the diversity amongst peacekeeping forces, while taking into account the number of troops, police officers, and observers. In other words, diversity does matter and can be beneficial, all else equal. Furthermore, much of the peacekeeping literature equates the UN mandate of a peacekeeping mission with the behaviour and effectiveness of peacekeeping missions. Yet, UN peacekeeping mandates come in a variety of forms with differing levels of engagement by peacekeepers.

Second, this book engages with security studies and, indirectly, with military sociology. We examine the behaviour of soldiers in nonconventional military missions and the extent that diversity of peacekeepers within missions affects cooperation with peacekeepers from other countries. This diversity also extends to mission leadership and peacekeepers on the ground. We examine nonconventional principal–agent relations where a large share of the agents, the peacekeepers, are from a different country than the principal, the Force Commander.

Third, this book makes a contribution to International Relations more generally. Peacekeeping missions are an interesting phenomenon to study in themselves but can also be used to study other core issues, such as the role of composition and diversity within military alliances, and how nonmaterial factors such as languages, norms, and cultures can affect military coordination and effectiveness.

Fourth, this book provides the first systematic conceptualization on mission composition and, building on pre-existing mechanisms, develops further mechanisms that include mission diversity acknowledging the centrality of nonmaterial and ideational factors. Clearly, this book advocates for further theorizing within the peacekeeping literature. In fact, we devote an entire chapter to reframing the analytical framework for studying peace operations and its (p.23) relatively new theoretical ramifications. Moreover, our empirical analyses combine qualitative and quantitative methods. We hope to foster a further dialogue between qualitative and quantitative scholarship on peacekeeping that should be supported to promote diversity in political science instead of pursuing a homogenization of the discipline.

I.5.2 Scope Conditions

There are at least five scope conditions for this book. The first, and most obvious, scope condition is that our research is only focusing on UN peacekeeping missions. We do not study operations that may be sponsored by the UN, but are conducted by individual countries, by NATO, or by regional organizations such as the Organization for Security and Co-operation in Europe. Second, our main dependent variables are the level of civilian victimization and battle-deaths between belligerents. Hence, this book only looks at one type of peace: ‘negative peace’. It also investigates the short-term effects of mission effectiveness. We do not examine mission effectiveness over the long term or after troop withdrawal. Moreover, we do not investigate long-term and after-withdrawal dimensions of positive peace (Di Salvatore and Ruggeri 2020).

Third, our main explanatory variables constructed around the core concepts of composition, diversity, and distance refer to UN troops in a peace operation. However, quite crucially, this book is not seeking to determine who the best peacekeepers are. We do not believe this is a useful question for understanding mission effectiveness. As we are interested in the internal distances within peace operations and external distances between peacekeepers and local populations, this question appears too narrow and context specific. Peacekeepers from country A may better suit a conflict in country Z, but not in country W. We are interested in how, by combining different national military forces, varying mission composition can affect mission effectiveness. Hence, asking which country provides the best peacekeepers misses the main point of our book. Our short answer is: it depends. It depends on who the other participants in the missions are, who is in charge as mission leaders, and where the mission operates.

Fourth, we are not examining the subnational variation of peacekeeping. Recent research has focused on geographic disaggregation of peacekeeping missions and found that the location and size of deployment is important (Costalli 2014; Ruggeri et al. 2016a, 2016b; Fjelde et al. 2019). Since we aim to (p.24) provide the first systematic analysis of mission composition and the effects of diversity on mission effectiveness, we were not able to embark on subnational analyses beyond the qualitative evidence included.

Finally, there are a number of relationships that this book does not examine. We do not feature any examination of the relationship between UN Headquarters and missions (Howard 2007). We have noted above that, over the past thirty years, there has been a shift from the majority of peacekeepers coming from Europe and North America to now coming from Asia and Africa. However, we do not examine the relationship between the ‘free riding’ of the ‘Global North’ over the ‘Global South’ in terms of troop contributions to missions (Cunliffe 2014). We are also not examining the relationships between missions and national governments (Auerswald and Saideman 2014) or between the military and civilian components within the UN mission (Sotomayor 2013). Finally, we do not include the relationships between missions and NGOs deployed in conflicts (Abiew 2003; Christie 2012). These relationships are all important factors in UN peacekeeping missions. However, our focus is on mission composition and how the combination of actors within a mission affects mission effectiveness.

I.6 Structure of the Book

Our book consists of one theoretical and four empirical chapters and a conclusion. The first chapter situates our contribution in the existing literature on peacekeeping and explains our analytical framework. For each empirical chapter, we present the detected mechanisms for each analytical level before delving into quantitative testing. Chapters 2, 3, and 4 explore the internal dimensions of diversity of mission composition. Chapter 2 focuses on field diversity, that is, diversity among peacekeepers, and how it affects peacekeeping effectiveness. Chapter 3 examines diversity within mission leadership—between Force Commanders and the Special Representative of the Secretary-General—and its impact on mission effectiveness. Chapter 4 explores the effect of diversity between Force Commanders and peacekeepers deployed. Chapter 5 turns to the external dimension of diversity of mission composition and looks at the relation between peacekeepers and local populations. In the conclusions, we discuss our findings, reflect upon their policy implications and outline avenues for future research.


(1) Fictitious name provided. For troops contributing countries here see:

(2) Authors’ interview, June 2019.

(3) We use in the book loosely the term ‘peacekeeping’, as the more recent literature has done. However, we use the terms ‘peacekeeping’ and ‘peace operations’ interchangeably and we do not imply specific features of an UN operation or the conflict when using the term ‘peacekeeping’.

(4) Report of the Panel on United Nations Peace Operations or ‘the Brahimi Report (UN 2000); United Nations Peacekeeping Operations: Principles and Guidelines or ‘the Capstone Doctrine’ (UN 2008); and Report of the High-level Independent Panel on Peace Operations on uniting our strengths for peace: politics, partnership and people or ‘the HIPPO report’ (UN 2015b).

(5) This said, the role to the international police deployed is crucial for local police departments to prevent, detect, and investigate crime and help maintain public safety and enforce the rule of law. As one would expect, the work of UN police officers is also complicated by the heterogeneity of policing approaches of very different countries. Yet, given the relatively smaller size of UN police, particularly during the early 1990s, only few studies include peacekeeping police and observer components, and they present mixed results. Hultman et al. (2014) find that larger deployment of UN peacekeeping troops, rather than UN police and observers, reduces the intensity of violence on the battlefield in ongoing civil wars on a monthly basis. Among recent reports and researches on the role of police forces in UN peacekeeping we would recommend William Durch and Michelle Ker’s Police in UN Peacekeeping: Improving Selection, Recruitment, and Deployment (Providing for Peacekeeping 6 (2013): 1–42) and Sabrina Karim and Ryan Gorman’s Building a more competent security sector: The case of UNMIL and the Liberian National Police (International Peacekeeping 23, no. 1 (2016): 158–91).

(6) Letter dated 1 November 2016 from the Secretary-General addressed to the President of the Security Council, S/2016/924 (UN 2016).

(7) Definition of less-developed economies according to the International Monetary Fund.

(8) Technically speaking, the SRSG is the head of the whole mission, including its civilian, military, and police components; whereas the two Deputy SRSGs are the heads of the civilian components, usually one focused on the political process and the other in the development and humanitarian agenda.

(9) We acknowledge that our definition of composition could be restrictive and rooted in a statist approach, however this definition provides a way to elaborate systematic operationalization and empirically verifiable variations.

(10) There are exceptions though, particularly when a mission is highly polarized, and to effectively capture the degree of diversity within a mission, we will actually use two indices, fractionalization and polarization, discussed in Chapter 2.

(11) Other colleagues have a more skeptical view about the feasibility of this mechanism (Howard 2019).

(12) The sample of host-countries we relied on are: Afghanistan, Angola, Burundi, Cambodia, Central African Republic, Chad, Côte d’Ivoire, Croatia, Cyprus, Democratic Republic of the Congo, El Salvador, Eritrea, Georgia, Guatemala, Haiti, Honduras, Iran, Iraq, Israel, Lebanon, Liberia, Macedonia, Mali, Mozambique, Nepal, Pakistan, Rwanda, Sierra Leone, Somalia, Sudan, Syrian Arab Republic, Tajikistan, and Uganda. Yet, after including control variables and country fixed-effects, we are left with twenty countries: Burundi, Cambodia, Central African Republic, Chad, Côte d’Ivoire, Croatia, Democratic Republic of the Congo, Georgia, Haiti, Iraq, Israel, Lebanon, Liberia, Mali, Rwanda, Sierra Leone, Somalia, South Sudan, and Sudan.

(13) For Gerring (2007, 239), in a pathway case the cross-case relationship needs to be known from the start.

(14) The Qualitative Appendix provides further information about each case.

(15) Authors’ interview, June 2019.

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