Once again, I shall refer to a very memorable historical event to see how propaganda shapes our thinking about events that have little to do with the truth.
If one looks back through the old reels of news on old Earth, one might see a particularly brutal scene of bedlam and chaos in a place called Ho Chi Mihn City, Vietnam (formerly Saigon). In this reel, one can see the national police director Nguyen Ngoc Loan take out a pistol, and in front of a stunned group of Western journalists, fires a single round point blank into a bound prisoners head, leaving him to die on the street with a gushing head wound.
The scene shocked the entire world and was used over and over again by propagandists to show the utter brutality of the Western powers against the North Vietnamese insurgents (Viet Cong). Much was learned from this video shot, just not the truth.
The truth was quite different. The man that was taken prisoner was a "captain" in the Viet Cong and was personally responsible for the deaths of members of a deputy Saigon police commanders family, as well as countless others during the Tet Offensive of 1968. When the deputy commander failed to follow the orders of the chief to execute this prisoner (since he was not in uniform, he is considered to be a spy and can be summarily executed according to the Geneva Convention), he did so himself. This was to insure that when he gave orders, they were to be carried out, and that there was no order that he would give to his subordinates that he would not do himself.
This kind of summary execution is not unknown for people caught performing acts of espionage during time of war. Why? Information costs the lives of your countrymen, and to insure that what information a spy has does not get back to his masters, the spy is killed. History is replete with examples of this, all quite "barbaric" in times of peace. During war time, it is a necessity.