Self-defense is a universally accepted exception to the prohibition of the use of force in international law, and it has been subjected to careful academic scrutiny. The prohibition of the threat of force, although equally important in terms of its normative status to the prohibition on use, has attracted far less academic commentary to date. This Article examines the relationship between the two prohibitions—of the use and threat of force—and considers the largely unexplored possibility of states utilizing a threat of force as a means of lawful defensive response: self-defense in the form of a threat. The status of this concept under international law is assessed, and the criteria that may regulate it are analyzed. This Article is based on an analogy between traditional “forcible” self-defense and the notion of threats made in self-defense. However, one cannot automatically apply the well-established rules of self-defense to a defensive threat, largely because of the practical differences between a threatened response and a response involving actual force.