The vast majority of writers agree that an armed attack by a non-state actor on a state, its embassies, its military, or other nationals abroad can trigger the right of self-defense addressed in Article 51 of the United Nations Charter, even if selective responsive force directed against a non-state actor occurs within a foreign country. Article 51 of the Charter expressly affirms the right of a state to respond defensively if an armed attack occurs,4 and nothing in the language of Article 51 restricts the right to engage in self-defense actions to circumstances of armed attacks by a state.5 Moreover, nothing in the language of the Charter requires a conclusion lacking in common sense that a state being attacked can only defend itself within its own borders.
Nothing in the language of Article 51 of the United Nations Charter or in customary international law reflected therein or in pre-Charter practice noted in Part I requires consent of the state from which a non-state actor armed attack is emanating and on whose territory a self-defense action takes place against the nonstate actor. In fact, with respect to permissible measures of selfdefense under Article 51, a form of consent of each member of the United Nations already exists in advance by treaty. In contrast, consent generally would be required for ordinary law enforcement measures,33 but selective use of armed force in self-defense is not simplistically law enforcement whether the measures of selfdefense are used in time of war or relative peace.
For these reasons, with respect to U.S. use of drones in Pakistan to target al Qaeda and Taliban leaders and fighters, it is clear that the U.S. would not need the express consent of Pakistan to carry out self-defense targeting.34 It is also clear that the U.S. has the right to use drones in Pakistan under Article 51 of the Charter in self-defense to protect U.S. troops from a continual process of al Qaeda and Taliban attacks35 on U.S. military personnel and others in Afghanistan that have emanated or been directed partly from territory in Pakistan for several years during a continuing international armed conflict and when al Qaeda and Taliban fighters move back and forth across the porous border that neither country effectively controls.
