I'm thinking that it would be best to have both military peacemaking and satyagraha (non-violent) peacemaking capability.
Non-violent has a lot of advantages. It's more effective in the long run. It does not breed more hate. It does not destroy lives and property. It probably costs less than a military.
But I think there are situations where a military would be better.
One advantage of a military is that it can be faster. For example, I have trouble imagining how a non-violent action could have quickly stopped the genocide in Rwanda. A rapid response military team could have saved perhaps hundreds of thousands of lives.
Another situation where a military team might work better is to stop a fighting force that is irrational, with leaders who may be insane or megalomaniacs. A good example is the "Lord's Resistance Army" in Uganda and eastern Congo. An international military incursion would amount to a police action to arrest the leaders of these "rebels" who commit countless atrocities. The followers could then be given help in re-integrating into society.
Presumably an international military force would be less likely than a national army to commit atrocities of its own in the fighting. It would also have the moral weight of international judgments behind it. The rebels would be less able to claim that they are the good guys.
A military force might also be used as a backup to a satyagraha force, in case a local government or rebel force started massacring the members of the satyagraha force. Admittedly this is problematic, because by having such a backup, the satyagraha force loses some of its moral strength.