First, I would not willingly be part of a killing unit -nor would I willingly put myself in a position to follow orders with which I did not agree. If I were drafted, I would be a conscientious objector. I would have no problem going into a combat zone as a medic or what-not, but I would not carry a gun.
Luk 3:14 And the soldiers likewise demanded of him, saying, And what shall we do? And he said unto them, Do violence to no man, neither accuse any falsely; and be content with your wages. (In other words... thou shalt not kill, bear false witness or covet -some read it differently, and that is between them and God. Some religious believe killing is acceptable in war due to Israel's involvement in war, but they did not war until they disobeyed and chided against God -and then were still guilty unless specifically directed by God.)
I've been shot at here at home from Corpus Christi to St. Cloud -drugged, poisoned, defamed, harrassed, harangued -had family members maimed and killed -others separated and systematically turned against each other. Some might say I have many valid reasons to kill -and if it weren't for the commandment, I'd probably agree -but what good would it do? I could probably take a few of them out before they got me, but I've been far more effective without a gun in my hand or murder in my heart. I would see it no differently in a combat zone -though others would most likely have a problem with it.
There is a difference between fear and cowardice. If we did not fear that our borders would be breached, our interests attacked or the innocent harmed, we would not have the National Guard, armed forces, etc... -fear is indeed the motivator. It is good to plead the cause of the widow and fatherless -but they can be protected without relying on sin one's self -however, this requires faith.
Obvioulsy, not everyone sees it this way -and we will have war until we no longer can -one way or another. To have peace on earth, war must be absent. I choose to live that way now. All that we think we have no choice but to do will lead us to self-annihilation.