Anyone following events in Iraq could be forgiven for thinking that we know relatively little about the dynamics of communal civil wars. In addition, anyone who remembers Bosnia and the rest of the "ugly nineties" has observed that the list of countries that have ripped themselves apart in communal civil wars seems to be growing. At the same time, resolving these conflicts is now seen as a deeply intractable problem. In almost every region we observe, communal civil wars are at or near the top of US policy agendas, most of all in Iraq, but also in the Israeli-Palestinian conflict and Darfur.
In reality, however, we have learned quite a lot about civil wars. Before the conflict in Bosnia, the conventional wisdom was that multi-communal states that had been torn apart by war should be put back together by power-sharing between communities or electoral reform. It was reasoned that such initiatives would compel politicians to appeal to all communities, not just their own, as well as to third party aid for reconstruction. Unfortunately, these approaches have rarely worked well.
Bosnia and subsequent conflicts demonstrate that communal settlement patterns matter a great deal. Earlier theories of communal conflict focused on factors such as the legitimacy of the state, histories of communal compromise and confrontation, and the intensity of communal grievances (whether real or exaggerated by ultranationalist mythmakers). By contrast, the conflict in Bosnia led the international community to develop a new theory centered on security dilemmas.
Whenever centrally imposed order in any communally divided state collapses, as in the case of the Soviet Union and Yugoslavia, or when the United States destroyed Saddam Hussein's regime in Iraq, communities must rely on their own resources for self-defense. In effect, the communally divided state becomes and behaves like a pocket international system.
The problem is that the material measures, and even the rhetorical measures, that communities use to mobilize for defense also pose offensive threats to other communities. The result is a security dilemma: a situation in which no community can provide for its own security without threatening the security of others. If and when this reaches the point that all sides are mobilized for war, or if large-scale violence has already commenced, it ceases to matter whether the original reasons for conflict were based on real material interests or were whipped up by political elites using populist rhetoric for their personal gain. Nor does it matter which side started the spiral into internal conflict; each group's mobilization now poses a real security threat to other groups.
The Case of Bosnia: A Security Dilemma
Of course, the nature and intensity of this mutual security dilemma can vary, depending in large part on communal settlement patterns. The more intermixed the settlement pattern of the hostile populations, the greater the offensive opportunities for each side--not only for organized forces but also for bandits and terrorists. Each group is likely to feel compelled to eliminate enclaves of the other community settled in its midst, lest these form fifth columns or become targets of "rescue offensives," as in the case of the Israeli offensive of 1948. In that mission, the Israeli government incorporated the isolated Jewish enclave of West Jerusalem into Israel by overrunning the Arab towns between Tel Aviv and Jerusalem.
The worst dangers are posed by people who are settled in places that make them appear both vulnerable and threatening to the other side at the same time. People in this situation are the ones most likely to become victims of ethnic cleansing. The heaviest fighting and worst atrocities in Bosnia happened in places where Serb and Muslim populations were most heavily intermixed--in the Drina Valley in Eastern Bosnia and in the North Central "Posavina Corridor," where Muslims lived not only with Serbs but also astride the only possible route that could connect the two main Serb enclaves in Bosnia. …