Résumé : The escalation of global terrorism, which reached its climax with the September 11 attack, produced an answer built around an aggressive rhetoric used by Washington, Tel Aviv and Moscow to respond to XXI century’s threats. My thesis is aimed at being an analysis of one of the most controversial methods of counterterrorism: the targeted killings. This method consists of the use of the lethal force by an international subject with the purpose, premeditation and deliberate decision of killing certain individuals because of their role in a terrorist group or their moral approval of terror tactics. For time reasons, I restricted my research to the use of this counterterrorism method by the three main actors involved in the fight against terrorism: Israel, the United States and Russia. In the first part, I gave a general outline of the norms that regulate the conduct of the hostilities in what is universally recognized as “the war on terror”. From the analysis of the doctrine and the factual situations in which States find themselves combating, the logical conclusion is that the war on terror does not always comply with the standards imposed by International Humanitarian Law for the qualification of a war. This does not mean that, as part of the doctrine claims, the fight against terrorism must be considered as a third genus with regard to the traditional division between armed conflicts of international or non-international character. In my opinion the fight against terrorism must be divided in its components, identifying which of these have the characteristics of an armed conflict (and among these which are or are not international in character) and which should be, on the other hand, regulated by the model of law enforcement and its own norms. The thesis is therefore constructed on the analysis of the legitimacy of the method of targeted killing in these two components of the fight against terrorism. As for the use of targeted killings in the situations which comply with the definition of armed conflict, be it international in character or not, I proceeded by verifying the consonance of this method with the fundamental principles of International Humanitarian Law which regulate the conduct of hostilities. From this verification one could draw to the conclusion that targeted killings are a legitimate method of conducting the hostilities only in the cases when (i) they are directed against legitimate military targets, that are combatants or civilians who take direct part in the hostilities and only for the duration of this direct participation; (ii) they respect the principles of proportionality and precaution trough preventive measures aimed at reducing the damages caused to the civilian population by the military effort and trough the comparison between the foreseeable direct military advantage and the foreseeable collateral damages; (iii) they have been planned after a careful evaluation of the military necessity of the attack with regard to the defeat of the enemy and not the enemy’s killing, keeping into consideration that the mere suspect does not constitute a legal basis for an action; (iv) they have been planned after carefully taking into consideration the possibility of using non lethal methods in order to reach the same goal. In situations that do not comply with the definition of armed conflict, targeted killings must be regulated by strict norms which mostly derive from human rights norm in general and the right to life in particular. One should keep in mind that in extreme situations a State could find itself in the position of having to use the lethal force, as ultima ratio, in order to protect the life of innocent individuals from an imminent threat. This might happen because, even in situations that are different from the conduct of hostilities, what is absolutely forbidden is the arbitrary privation of life, not the privation of life in itself. In the law enforcement model, targeted killings are therefore strictly limited by absolute necessity and procedural duties. For the use of lethal force by a State against an individual to be legitimate in situations that cannot be qualified as armed conflict, certain cumulative conditions must be met: (i) the respect of the State law and International Law according to the law enforcement paradigm. (ii) the duty to carefully planning and investigate before and after the killing; (iii) the lethal force must not be used in order to kill but in order to punish; (iv) the use of the lethal force must be exclusively aimed at protecting human life from severe threats; (v) the use of the lethal force must be absolutely necessary from a qualitative, quantitative and temporal point of view; (vi) the death must be the ultima ratio, inevitable but not desired and certainly not the explicit aim of the operation. In this moment when the adequateness of International Humanitarian Law is questioned and when self-evident violations of human rights are carried out, I also decided to strongly underline the complementarities of these sets of rules, which both aim at protecting the individuals involved in a situation of violence. Combating terrorism requires new strategies, but cannot happen without respecting International Humanitarian Law and human rights: the States involved in the fight against terrorism must recognize that this is the only adequate and legitimate way to walk in order to eradicate the menace of terror without falling in an unstoppable spiral of violence.