Certain regions of the world experience more conflict than others.
Previous analyses have shown that a civil war in one country significantly
increases the likelihood that neighboring states will experience conflict.
This finding, however, still remains largely unexplained. We argue that
population movements are an important mechanism by which conflict spreads
across regions. Refugee flows are not only the consequence of political
turmoil—the presence of refugees and displaced populations can also
increase the risk of subsequent conflict in host and origin countries.
Refugees expand rebel social networks and constitute a negative
externality of civil war. Although the vast majority of refugees never
directly engage in violence, refugee flows may facilitate the
transnational spread of arms, combatants, and ideologies conducive to
conflict; they alter the ethnic composition of the state; and they can
exacerbate economic competition. We conduct an empirical analysis of the
link between refugees and civil conflict since the mid-twentieth century,
and we find that the presence of refugees from neighboring countries leads
to an increased probability of violence, suggesting that refugees are one
important source of conflict diffusion.We
would like to thank the participants in the “Resources, Governance
Structures, and Civil War” Workshop at the European Consortium for
Political Research in Uppsala, Sweden, 13–18 April 2004, for early
feedback on previous versions of this article. We would also like to thank
Anis Bajrektarevic, Lars-Erik Cederman, David Cunningham, Kristian Berg
Harpviken, Béla Hovy, Sarah Lischer, Monty Marshall, Erik Melander,
Will H. Moore, Magnus Öberg, and Michael Ward for providing us with
data and helpful comments, as well as Jan Ketil Rød for permission
to reproduce the map from the program ViewConflicts in Figure 1. Finally, we are grateful for the comments
and suggestions of the editors of International Organization and
the anonymous reviewers. This research was supported by a grant from the
National Science Foundation (SES-0351670).