In response to a question from Yahya:
A peaceworker is an individual or member of an organization that
undertakes to resolve violent conflict, prevent the rise of new
violent conflicts, and rebuild societies damaged by war.
The term peaceworker is usually reserved for civilian, unarmed members
of non-governmental organizations.
From
http://en.wikipedia.org/wiki/Peaceworker
Also see
http://www.peaceworkersus.org/