The present paper is devoted to a detailed presentation of a new Military Ethics doctrine of fighting terror. It is proposed as an extension of the classical Just War Theory, which has been meant to apply to ordinary international conflicts. Since the conditions of a fight against terror are essentially different from the conditions that are assumed to hold in the classical war (military) paradigm or in the law enforcement (police) paradigm, a third model is needed. The paper proposes such (...) a model in the form of principles that should govern the activity of a democratic state when faced with terror. Eleven principle are proposed. Two are on the level of the state, including the Principle of Self-Defense Duty. Six are related to military preventive acts against activities of terror, including new formulations of a Principle of Military Necessity, a Principle of Distinction, and a Principle of Military Proportionality. Principles of Low Probabilities, Time Span Considerations and Professional Understanding are also included. Finally, three principles that are related to consciousness-directed activities against terror are added: a Principle of Permanent Notice, a Principle of Compensation, and a Principle of Operational Deterrence. The exposition of the principles is accompanied by arguments about their moral justification. The doctrine has been developed on the background of the IDF fight against acts and activities of terror performed by Palestinian individuals and organizations. (shrink)