This book provides an in-depth view of the GRU, the Russian military intelligence agency, in cyberspace. With its Soviet roots, the GRU is a secretive organization that conducts hostile operations in both kinetic and cyber domains. Particularly in cyberspace, the GRU has developed powerful capabilities through various military units and a full spectrum of techniques. These capabilities allow the agency to conduct a wide range of cyberspace operations, from sabotage and espionage to psychological warfare. The complexity of some of these operations, combined with the GRU?s high risk appetite and Spetsnaz-like mindset, makes it one of the most formidable and sophisticated cyber threat actors.