MANY GOVERNMENTS around the world identify stopping and stemming "ethnic and religious hatreds" as a major foreign-policy priority. Quite simply, in the words of the 2006 U.S. National Security Strategy, such "conflicts do not stay isolated for long and often spread or devolve into humanitarian tragedy or anarchy." Yet, ethnic conflicts do not simply appear out of thin air. They can be traced primarily to the decisions of political leaders. The spread of ethnic conflict is not automatic either. For existing ethnic conflicts to move beyond their original borders, the relevant actors-ethnic communities, states and other private-interest groups-need to make a choice. If they choose to expand the conflict, they need three things: the motive, the means and the opportunity.
Ethnic conflict spreads in two principal patterns: diffusion and escalation. Diffusion means that the existence of one ethnic conflict leads to the occurrence of others, either elsewhere in the same state or in other, often neighboring, states. Escalation, on the other hand, describes a situation in which more actors become involved in the same conflict as belligerent parties.
The traditional patterns of the spread of ethnic conflict exhibit close links between escalation and diffusion and typically occur when ethnic groups mobilized on the basis of some combination of greed, grievance or security concerns confront each other, the states in which they live or both. Ethnic groups, states or a combination of both can drive these conflicts. They are predominantly played out on a regional level (e.g., in the western Balkans, in the Greater Middle East) and involve not only the immediate neighbors of an ongoing conflict, but they also draw in regional and great powers.
