"This report presents an overview of the threat landscape in cyberspace, including the types of offensive weapons available, the targets they are designed to attack, and the types of actors carrying out the attacks. It presents a picture of what kinds of offensive and defensive tools exist and a brief overview of recent attacks. The report then describes the current status of U.S. capabilities, and the national and international authorities under which the U.S. Department of Defense carries out cyber operations. Of particular interest for policy makers are questions raised by the tension between legal authorities codified at 10 U.S.C. [US Code], which authorizes U.S. Cyber Command to initiate computer network attacks, and those stated at 50 U.S.C., which enables the National Security Agency to manipulate and extrapolate intelligence data--a tension that Presidential Policy Directive 20 on U.S. Cyber Operations Policy manages by clarifying the Pentagon's rules of engagement for cyberspace. With the task of defending the nation from cyberattack, the lines of command, jurisdiction, and authorities may be blurred as they apply to offensive and defensive cyberspace operations. A closely related issue is whether U.S. Cyber Command should remain a sub-unified command under U.S. Strategic Command that shares assets and its commander with the NSA [National Security Agency]. Additionally, the unique nature of cyberspace raises new jurisdictional issues as U.S. Cyber Command organizes, trains, and equips its forces to protect the networks that undergird critical infrastructure. International law governing cyberspace operations is evolving, and may have gaps for determining the rules of cyberwarfare, what constitutes an 'armed attack' or 'use of force' in cyberspace, and what treaty obligations may be invoked."
CRS Report for Congress, R43848