It was Jesus who made the Live by the sword die by the sword quote ? and it was not meant to justify murder. It is meant to explain how the world works. How there are unintended consequences of violence that always come back to hurt you.
It amazes me that there are so many people who misunderstand this -there is no critical thinking when it comes to soldiers. It's mostly because of how we venerate soldiers and pathetic victims like Gabby Giffords. The government wants us to be subservient to them and their soldiers, essentially they want us all to be helpless victims like Giffords.