Usually this involves seeing killing other people [who are mostly strangers] as an ethical choice. Thats a skewed morality to begin with right there and then the training is all about abandoning independent moral choices in favour of group killing. The guy who creeps up on the dozing sentry and slices his throat [and the throats of his trusting, sleeping companions] is also a soldier.
Yes, a soldier's premier responsibility lies in killing or in preparing to kill the designated enemies of their country. It is against this backdrop of violence that soldiers must adhere to the highest standards of personal and professional integrity, even as they pursue a life's work which is little appreciated or understood by the civilians to and for whom the soldier is responsible.
US Air Force General Sir John Hackett, said this during a speech at the Air Force Academy:
"A man can be selfish, cowardly, disloyal, fleeting, false, perjured, and morally corrupt in a wide variety of other ways and still be outstandingly good in pursuits in which other imperatives bear than those upon the fighting man. He can be a superb creative artist, for example, or a scientist in the very top flight, and still be a very bad man. What the bad man cannot be is a good soldier."
While it is true that, in the heat of combat, evil persons who kill the enemy can, for that short time, be considered "good soldiers," their corruption and venality disqualify them from being good soldiers for the 99 percent of the time they otherwise spend in the armed forces. Good people do not always make good soldiers, but bad people are always bad soldiers.
I will say it again: Soldiers who are not morally competent are not militarily competent. Those in uniform who know no more of their ostensible profession than saluting and shooting are atrocities waiting to happen, whether in Iraq, Serbia, or My Lai.
So in answer to your post, yes, there is killing involved in being a soldier. There have been soldiers who commit horrible acts in the name of "following orders". It is the military's responsibility to find those soldiers and weed them out
before they have a chance to go do those kinds of things. It is each soldier's duty and task to act in the highest ethical tradition.