国連PKOのサイトを見てみると、大原則としてこう書いてあります。
Impartiality is crucial to maintaining the consent and cooperation of the main parties, but should not be confused with neutrality or inactivity. United Nations peacekeepers should be impartial in their dealings with the parties to the conflict, but not neutral in the execution of their mandate. Just as a good referee is impartial, but will penalize infractions, so a peacekeeping operation should not condone actions by the parties that violate the undertakings of the peace process or the international norms and principles that a United Nations peacekeeping operation upholds.