The doctrine of “responsibility to protect” obliges all states to protect populations from “atrocity crimes”—namely, genocide, war crimes, crimes against humanity, and ethnic cleansing—under three “pillars” of protection. Pillar One requires a state to protect its own population from atrocity crimes. Pillar Two obliges the international community to help states to exercise this responsibility through diplomatic, humanitarian, and other peaceful means. When both of these approaches fail, states must pursue a “Pillar Three” strategy: the UN Security Council must “take collective action, in a timely and decisive manner.”