It depends on the situation, if they have firearms and are attacking you of course retaliation would be self-defense. Though understand that why would Kashmiris ever have to raise arms in the first place? The problem is occupation, you can argue self-defense, but they can argue liberation, freedom, defending their homeland/territory from foreign occupier. So their argument outweights your "self-defense" argument, you wouldn't have to use the "self-defense" argument had there been no occupation in the first place.
So really it is a matter if one wants to look at the smaller picture or bigger picture, if you look at smaller picture "self-defense" argument of Indian soldiers, if bigger picture than Kashmiri position is valid and righteous.