People who are trained to fight and kill and who are gung-ho about it have a vested interest in getting into actual battle. They feel can test and prove their worth only by actual combat. Thus the military has a need for occasional conflict in order to keep themselves sharp.
What a negative, self-defeating interest! War is NEVER productive. It is only and always destructive of life and property. That is one reason that civilian leaders must exercise judgment in their handling of the military and always keep them strictly in check.