Almost all countries do a good job of brainwashing their soldiers - its all for patriotism and thus killing the enemy is justified. However, dictatorial governments do even a better job. North Korea is a good example. The picture below puts some light on this phenomena.
Female North Korean soldiers march during a mass military parade on Kim Il Sung Square in Pyongyang to mark the 60th anniversary of the Korean War armistice Saturday, July 27, 2013. (AP Photo/David Guttenfelder)