But waging a guerrilla war doesn't necessarily involve terrorism, defined as intentionally killing non-combatant civilians to change the way they behave and think. For example ambushing military units and so forth isn't in itself terrorism, however much the press offices might try to paint it as such.

In a situation where the aim is to "win hearts and minds" terrorism doesn't make much sense for either side. Of course typically that doesn't stop it happening from both sides.

And the fact that the killing by either sides may not be "terrorism", in that sense, doesn't make it any less horrible, or mean that it is justified.