Sometimes the people in the different color uniform are acting like animals, these animals are killed, not murdered.
Enemy combatants are not murdered,
The intentional death of a human being is always murder.
Societies then create moral and legal exemptions to allow murders that the people consider necessary.
Sometimes the people (in uniform) dehumanize the enemy to make it easier to murder them.
It's an extremely ugly road to go down: http://i.imgur.com/riixJyL.jpg
And I'm not exaggerating: http://i.imgur.com/ODMmE5i.jpg
I'm glad we're civilized enough to have stopped making dehumanizing propaganda the official government policy.
I hope you can catch up with the civilized world.