Cécile Fabre draws back the curtain on the ethics of espionage and counterintelligence.Espionage and counter-intelligence activities, both real and imagined, weave a complex and alluring story. Yet there is hardly any serious philosophical work on the subject. Cécile Fabre presents a systematic account of the ethics of espionage and counterintelligence.She argues that such operations, in the context of war and foreign policy, are morally justified as a means, but only as a means, to protect oneself and third parties from ongoing violations of fundamental rights. In doing so, she addresses a range of ethical questions: are intelligence officers morally permitted to bribe, deceive, blackmail, and manipulate as a way to uncover state secrets? Is cyberespionage morally permissible? Are governments morally permitted to resort to the mass surveillance of their and foreign populations as a means to unearth possible threats against national security? Can treason ever be morally permissible? Ca