The academic study of warfare has expanded considerably over the past 15 years. Whereas research used to focus almost exclusively on the onset of interstate war, more recent scholarship has shifted the focus from wars between states to civil conflict, and from war onset to questions of how combatants wage and terminate war. Questioned as well are the longer-term consequences of warfare for countries and their populations. Scholarship has also shifted away from country-conflict-year units of analysis to micro-level studies that are attentive to individual-level motives and explanations of spatial variation in wartime behavior by civilians and combatants within a country or armed conflict. Today, research focuses on variations in how states and rebel groups wage war, particularly regarding when and how wars expand, whether combatants comply with the laws of war, when and why conflicts terminate, and whether conflicts end with a clear military victory or with a political settlement through negotiations. Recent research also recognizes that strategic behavior continues into the post-conflict period, with important implications for the stability of the post-conflict peace. Finally, the consequences of warfare are wide-ranging and complex, affecting everything from political stability to public health, often long after the fighting stops.
Alyssa K. Prorok and Paul K. Huth
Kristin P. Johnson and Ashlea Rundlett
Conflicts that occur along ethnic or nationalist lines are often the most protracted, violent, and difficult to resolve in the long term. Civil wars are often divided into two distinct types: ethnic/religious wars (identity), and revolutionary wars (nonidentity). The distinction between these conflict types is based on whether cleavages within a society occur along ethnic lines or along lines that cut across ethnic divisions and are focused on issues including class, ideology, or seeking significant policy orientation of change. The most significant theoretical and empirical contributions to the understanding of ethnic conflicts in recent years come from the disaggregation of civil wars focusing on micro- and group-level dynamics. This disaggregation supports theoretical advancement and a departure from using macro-level data with micro-level mechanisms supports transition from a monadic to dyadic study of ethnic conflict, and supports examination of potential causal mechanisms of ethnic violence. Scholarly traditions and theoretical approaches explaining identity mobilization along ethnic or nationalist lines, the contributing factors that explain the transition from mobilization to the exercise of political violence, the duration of identity-based conflicts, and the long-term prospects for settlement of the conflict have enjoyed a proliferation of studies using newly available data featuring subnational units. These include explanations of conflicts based in sociological foundations focused on the formation and maintenance of identity, structural explanations for internal conflict focus on the capacity of the state and the distribution of political authority within a political system, and the opportunity for rebellion.
Timothy J. A. Passmore
UN peacekeeping serves as the foremost international tool for conflict intervention and peace management. Since the Cold War, these efforts have almost exclusively targeted conflicts within, rather than between, states. Where traditional peacekeeping missions sought to separate combatants and monitor peace processes across state borders, modern peacekeeping in civil wars involves a range of tasks from intervening directly in active conflicts to rebuilding political institutions and societies after the fighting ends. To accommodate this substantial change, peacekeeping operations have grown in number, size, and scope of mandate. The increasing presence and changing nature of peacekeeping has sparked great interest in understanding when and how peacekeeping is used and how effective it is in delivering and sustaining peace. Significant advances in peacekeeping data collection have allowed for a more rigorous investigation of the phenomenon, including differentiation in the objectives, tasks, and structure of a mission as well as disaggregation of the activities and impact of peacekeepers’ presence across time and space. Researchers are particularly interested in understanding the adaption of peacekeeping to the unique challenges of the civil war setting, such as intervention in active conflicts, the greater involvement and victimization of civilians, the reintegration of rebel fighters into society, and the establishment of durable political, economic, and social institutions after the fighting ends. Additional inquiries consider why the UN deploys peacekeeping to some wars and not others, how and why operations differ from one another, and how the presence of and variation across missions impacts conflict countries before and after the fighting has stopped.
Caroline A. Hartzell and Amy Yuen
With wars—not just global, but civil wars and other domestic infightings—still being rampant in the modern world, scholars have begun to develop interest in identifying the conditions that can help establish a durable peace. Peace is a lack of conflict and freedom from fear of violence between social groups. Commonly understood as the absence of war or violent hostility, peace often involves compromise, and therefore is initiated with thoughtful active listening and communication to enhance and create genuine mutual understanding. The study of the durability of peace has greatly evolved through the years, and one of its implications is that recent empirical work on this topic has focused on civil war. Most of this study has been tailored in response to the model of war, a theory of armed conflict which presents war and peace as stages of a single process. Furthermore, this analysis on peace duration revolves around for main themes: the characteristics of conflict and conflict actors, belligerent-centered dynamics, the role of third parties, and the developments in the measurement, estimation, and the study of peace duration. Under the conceptions of peace, sustainable peace must be regarded as an important factor for the future of prosperity. Throughout the world, nurturing, empowerment, and communications are considered to be the crucial factors in creating and sustaining a durable peace.
Idean Salehyan and Clayton L. Thyne
Civil war is an armed conflict between the state and another organized domestic party over a contested political incompatibility, which results in a number of casualties exceeding a certain threshold for both parties. Attempts to operationalize these criteria have produced many data sets, which conceptualize civil war as distinct from one-sided violence, organized crime, and communal fighting. Civil wars are devastating for states experiencing them, their neighbors, and the entire global community. Combatant and civilian deaths, rape, massive refugee flight, negative impacts on economy and infrastructure, spread of infectious diseases, global spread of illegal narcotics, and the promotion of terrorism are all consequences of civil wars. Theories explaining why civil wars occur focus on objectives of the rebels, ability of rebels to successfully challenge the government, influence of external actors on interactions between the government and the opposition, external financing of potential rebel groups, and impact of a state’s neighbors on the likelihood of civil conflict or how neighboring conflicts and refugee communities serve as breeding grounds for cross-border rebel movements. Conflicts persist until neither side believes that it can achieve unilateral victory and continued fighting is costly. Governments are more likely to win early when they have large armies, but time to government victory increases when they are faced with secessionist rebels and when external parties are involved. Meanwhile, external mediation diminishes informational and credible commitment problems during bargaining and reduces conflict duration. Promising directions for future research on civil war include geographic disaggregation, survey research, and computational/agent-based modeling.
The political economy of violent conflict is a body of literature that investigates how economic issues and interests shape the dynamics associated to violent conflict after the Cold War. The literature covers an area of research focusing on civil wars—the predominant type of conflict in the 1990s and early 2000s—and an area of research focusing on other types of violent conflict within states, such as permanent emergencies, criminal violence, and political violence associated to turbulent transitions. The first area involves four themes that have come to characterize discussions on the political economy of civil wars, including research on the role of greed and grievance in conflict onset, on economic interests in civil wars, on the nature of conflict economies, and on conflict financing. The second area responds to the evolution of violent conflict beyond the categories of “interstate” or “civil” war and shows how political economy research adapted to new types of violent conflict within states as it moved beyond the “post-Cold War” era. Overall, the literature on the political economy of violence conflict emphasizes the role of informal systems behind power, profits and violence, and the economic interests and functions of violence underlying to violent conflict. It has also become a conceptual laboratory for scholars who after years of field research tried to make sense of the realities of authoritarian, violent or war-affected countries. By extending the boundaries of the literature beyond the study of civil wars after the Cold War, political economy research can serve as an important analytical lens to better understand the constantly evolving nature of violent conflict and to inform sober judgment on the possible policy responses to them.
Clionadh Raleigh, Frank D. W. Witmer, and John O’Loughlin
Analysis of civil and international conflict is an important component of the fields of political science and international relations. The theories that animate the study of conflict have focused on a combination of economic and ethnic–ideological motivations, along with political and systemic factors such as alliances and support from external benefactors. However, few studies have presented a coherent and compelling account of the persistence and patterns of conflict since 1945. Many conflict studies that consider spatial phenomena ignore the particularities of the data and the context of spatial relationships. Three strands of research on spatial analysis of war can be identified: studies that explored how neighboring states influence the propensity for the international spread of disputes; studies that lend support to both spatial heterogeneity and dependence explanations of civil war patterns in developing states; and work that incorporates space into quantitative civil war studies by modeling how subnational characteristics affect civil war risk. In general, the qualitative literature on conflict has provided insights that help to identify predictive variables for quantitative analysis, in particular the local spatial distribution of violence and its trends over time. This is evident in the case of the Democratic Republic of the Congo, where violent events have erupted since independence in 1960. Despite the substantial progress in conflict research, there are a number of areas that deserve further investigation, including the specific contextual factors that govern the ebb and flow of conflict such as terrain, forest cover, distribution of supportive and opponent populations.
Stathis N. Kalyvas and Paul D. Kenny
A civil war, also known as intrastate war, is a war between organized groups within the same state or country. It is a high-intensity conflict that often involves regular armed forces. One of the reasons for the lack of consensus in the study of civil war is disagreement over what exactly civil war means. Theoretically, civil war overlaps with other categories of armed conflict, particularly revolution, political violence, ethnic conflict, and terrorism. Civil wars since the end of World War II have lasted for over four years on average, a considerable rise from the one-and-a-half-year average of the 1900–1944 period. While the rate of emergence of new civil wars has been relatively steady since the mid-19th century, the increasing length of those wars has resulted in increasing numbers of wars ongoing at any one time. Since 1945, civil wars have resulted in the deaths of over 25 million people, as well as the forced displacement of millions more, along with economic collapse. According to scholars of civil war research, the causes of civil war include economic motivations or greed, and political or social grievances. Greed-based explanations focus on individuals’ desire to maximize their profits, while grievance-based explanations center on conflict as a response to socioeconomic or political injustice. A third concept, opportunity-based explanations, talks about factors that make it easier to engage in violent mobilization.
Joyce Neu and Louis Kriesberg
The field of conflict analysis and resolution (CAR) is primarily defined as ideas about and applications of ways in which conflicts can be addressed constructively. The boundaries of the field cannot be sharply drawn. There are scholars, practitioners, and outside analysts who sometimes apply conflict resolution ideas and methods but who do not self-identify as belonging to the field. They do, nevertheless, contribute to the field. The field also refers to people designated or self-identified as conflict analysis and resolution scholars and/or practitioners. This article focuses on the development of the CAR field as an interdisciplinary social science endeavor within the broad international relations domain. The major periods covered include (1) development of the field and its preliminary beginnings from 1914 to 1945; (2) emergence of CAR as a field between 1946 and 1969; (3) expansion and institutionalization from 1970–1989; (4) diffusion and differentiation from 1990–2008; and, (5) advances and challenges 2009 through 2017. From 1914 to 1945, as a result of World War I, there was a rise in pacifism. The creation of the United Nations in 1945 following World War II was intended as a means to prevent war and maintain peace. CAR research focused on analyzing the causes of violent conflicts. Researchers drew on psychoanalytic tools to examine, for example, attributes of leaders and social movements. From 1946 to 1969, as a result of the Cold War and national liberation struggles, the world experienced an increase in the number of conflicts. Governmental organizations worked to avert a possible nuclear war and to limit conflict escalation through the United Nations and by the creation of forerunners to the European Union. In the nongovernmental sector, high-level unofficial meetings began taking place to build peace and reduce tensions. CAR research grew and included the use of game theory and rational models. The period of expansion and institutionalization (1970–1989) saw the growth of alternative dispute resolution that positively affected the creation of new CAR institutions. Nongovernmental CAR organizations grew in number and effectiveness offering dialogue and problem-solving workshops to disputing parties. Research focused on nonviolent means of resolving conflicts as well as how conflicts can be waged constructively. From 1990 to 2008, the field witnessed a period of diffusion and differentiation. The end of the Cold War gave way to a period with fewer armed conflicts. Nongovernmental organizations and university programs in CAR increased. Intergovernmental organizations such as the UN and the African Union began to focus on professionalizing their mediation and peacemaking efforts. The period from 2009 through 2017 saw the field continue to grow. New challenges included the quashing of nonviolent resistance movements in the Middle East and North Africa, the impacts of climate change, the rise in terrorism, and the widespread use of technology for both positive and negative impacts on peace. This period saw a dramatic increase in the application of CAR research and experience in governmental and intergovernmental organizations’ work.
Predictive models, which includes forecasting models, are used to study all types of conflict and political violence, including civil wars, international conflict, terrorism, genocide, and protests. These models are defined as those where the researcher explicitly values predictive performance when building and analyzing the model. This is different from inferential models, where the researcher values the accurate operationalization of a theory, and experimental or quasi-experimental designs where the focus is on the estimation of a causal effect. Researchers employ preditive models to guide policy, to assess the importance of variables, to test and compare theories, and for the development of research methods. In addition to these practical applications, there are more fundamental arguments, rooted in the philosophy of science, as to why these models should be used to advance conflict research. Their use has led to numerous substantive findings. For example, while inferential models largely support the democratic peace hypothesis, predictive models have shown mixed results and have been used to refine the scope of the argument. Among the more robust findings are the presence of nonlinear relationships and the importance of dependencies in all types of conflict data. These findings have implications for how researchers model conflict processes. As predictive models become more common and more integrated into the study of conflict, it is important that researchers understand their underlying components to use them appropriately.