I do not have my dictionary with me, but, as I understand it, the term “peacekeeper” refers to a particular event, while “peacekeeping” is used when talking about a vision. I think that peacekeeping refers to the act of preserving peace around the world, while a peacekeeper is involved in a particular event. That is what I understand to be the basic difference between “peacekeeping” and “peacekeeper”.
Based on my definition, do you prefer the term “peacekeeping” or “peacekeepers”?