Modulo Israel's unpopularity: how would another nation state, say, Korea, act, if a non-state organization attempted to assert its authority to act in substant

Modulo Israel's unpopularity: how would another nation state, say, Korea, act, if a non-state organization attempted to assert its authority to act in substantial force to override the authority of the nation state's government? It is my theory that, up to niceties, that such acts are a form of war; the nation's government would be under major pressure from its public to act in reciprocal force.