There's an old Christian line of thinking that allows for the moral use of limited violence in certain specific situation. The concepts are usually collected under the heading of the "Just War Theory" which had its Christian roots in the writings of Augustine of Hippo though the ideas are first found in Cicero.
Last week the United States entered its third concurrent arena of global conflict as US air and naval forces began to take part in the UN mandated "No-Fly" zone in Libya. Because of the specifics of the situation, and the real threat to civilian lives by the Libyan government, people have argued that our involvement is "moral".
NPR has an interview with Prof. Sean Casey (an ethicist from Wesleyan Theological Seminary in DC that takes a close look at the particulars of the question.
"MARTIN: Is this a genocide or is this a civil war?
Prof. CASEY: In essence it's both. We have a specific example of a potential atrocity and that's separate from the question of intervening in a civil war on a large scale. I think the president has said we're not going to intervene militarily to settle that civil war militarily. He thinks that there are economic and diplomatic courses that we can pursue, short of actually putting boots on the ground. So, there really are two moral issues at play here.
MARTIN: Is this a subject of debate right now among, well, I want to say particularly Christian theologians who have a very articulated sort of philosophy here, but, you know, theologians of other belief systems. I mean is this a topic of discussion right now?
Prof. CASEY: Oh, absolutely. Absolutely. I mean, my Facebook page is just littered with comments. And there are a number of us having this discussion as we write and as we do media events, people respond to that. So there's a very vigorous debate going on in discussion.
My sense is, interestingly enough, there actually is a large amount of support among, I would say, theologians, philosophers and ethicists that this is a just intervention. But there's a lot of anxiety knowing that the longer narrative in Libya may yet go awry, go astray morally. So the discussion is going to be ongoing."
Read the full interview here.