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Questions about the drone campaign, which is being waged under the congressional authorization for the 2001 Afghan invasion, are piling up. What is the legality of killing people far from any battlefield? How do we decide to use a strike rather than a ground operation? What weight is given to the likelihood of civilian casualties? Does the authorization extend only to al-Qaeda members, to its loose network of affiliates, or to any Islamic militant? How much consideration is given to the possibility of so-called blowback attacks when drone technology becomes available to terrorists and other enemies?