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Peace Operations

Explore research on the use of peace operations as a tool to help prevent mass atrocities.

Overview of the Evidence on Peace Operations

Our research review includes 96 reports: 8 that address the effects of peace operations on mass atrocities and 92 that address the effects of peace operations on closely related outcomes, such as civilian killings, human rights violations, and conflict recurrence. It found the following:

  • A mix of findings as to whether peace operations were effective in helping prevent mass atrocities or closely-related outcomes, and 
  • Relatively strong evidence on the association between several design factors and greater effectiveness of peace operations in helping prevent mass atrocities.
    • We found the strongest evidence that having a high quantity of troops; a high level of commitment; and international support or coordination were associated with peace operations success. 
    • Other factors supported by relatively strong evidence include the peace operation being unbiased; having clear policy objectives; being well-informed; and receiving cooperation from the host country.

About Peace Operations


Peace operations are composed of “military and/or civilian personnel deployed by one or more third-party states, frequently but not necessarily under the auspices of a global or regional organization” (Mullenbach 2005, p. 529). The mandates and composition of peace operations can vary widely, from civilian observer missions to missions authorized to use military force to enforce the peace. Common goals include mitigating hostilities, restoring state authority, preventing recurrence of civil war, and/or achieving humanitarian goals, including the protection of civilians.

Theory of Change

If peace operations help prevent the outbreak or recurrence of armed conflict, they would reduce the likelihood of mass atrocities because armed conflict is the strongest risk factor for mass atrocities. In addition, if peace operations provide direct physical protection to civilian populations; defeat, detain, or degrade the capacity of atrocity perpetrators; and/or shift armed actors’ calculations of the costs and benefits of targeting civilians (e.g., by publicizing violations), they would reduce the likelihood or severity of mass atrocities.

Strategies This Tool Can Support

(1) Dissuading potential perpetrators from committing mass atrocities
(2) Protecting vulnerable civilian populations