The Duty to Secure

States have social contractual duties to provide security for their people, but just what measures are morally required? Should states be obligated to address real/objective existential threats via securitization (i.e., threat-specific, often liberty defying, rigorously enforced and sometimes forcible emergency measures)? Do non-state actors or international organizations also have a moral duty to securitize and, if so, why, when, and to whom? Would such duties pertain only to populations of one's own state or also to people in other states? 'The Duty to Secure' offers answers to these and other questions, setting out a rigorous theory of morally mandatory securitization that examines the duties of actors at all levels of analysis. Morally mandatory securitization has practical implications, including for NATO's Article 5 and the responsibility to protect norm, both of which currently take account of only a narrow range of threats.