The Nairobi Law Monthly just published my article on Kenya’s use of force in its crackdown on Al-Shabaab and efforts to secure the borders. I argue that the use of force in self-defense against Al-Shabaab, a non-state actor, does not have proper legal grounding under Article 51 of the Charter of the United Nations and indeed under customary international law. Nevertheless, if Kenya now has a proper legal basis in proceeding against the group, its use of force is still governed by international law. Such use of force must be necessary and proportionate.