I've got soul but I'm not a soldier!

A revelation today. My son, nearly nine, has expressed a new life aspiration, to be a soldier! I'm shocked to the core.
"Because so many people are dying!" And he wants to help. Not for King and Country. Not in the killing, he wants to help. There's something noble in this. To Fight, to Protect, to Defend!
I hadnt thought through any desire to be in warfare or a battle with any sense of justice any sense at all of a positive putcome, surely there must be sometimes. Or is liberation usually just a transfer from one tyranny to another?
Can a combatant be a subversive peacemaker?