I guess innocent men women and children were enemies. I have no problem with my people killing and scalping savage murderers who terrorize innocent people and having a bounty for it.
They probably felt the same way. They saw themselves as the Innocent ones who the white man sold them blankets infested with sickness which they had no immune to. Or whom the white father in Washington who promised them this and that for their land and then herded them off like cattle to die on reservations. Both sides have blood on their hands.