OK,
I got no problem killing people who are our enemies. Done it before, hope not to do it again. However, I don't try to lie to myself in justifying that any one death is better than another. All are wrong and immoral.
Someone has to take it on themselves to protect what is right, even if it means sinning in the act. I don't think that when I die God is going to say, "Hey, Dutch, that one guy you killed on 15 Nov 2003? It's ok. He was a dick.'
Dutch, you have already been down this road, I am sure.
There is an enemy. He wants to kill you and kill innocents.
God will say: "Dutch -- I know it hurt you to kill someone to protect the best Country that I put on Earth. A Country with the heart I so wanted to put within all, but in this one it stuck. A Country that produced you, Dutch."
The fact this bothers you speaks to your humanity and your goodness, Dutch.
I think God will have special welcome for you and those who do violence for the greater good. A specific and easily defined good.
I don't rate on that scale -- you do.