Abstract
The Department of Homeland Security is the newest cabinet-level department in the US government. While many of the roles and functions regarding “homeland security” was long established, after the 9/11 terrorist attacks, it was recognized that a new paradigm was needed to provide for the internal security of the United States, while providing for the detection, and mitigation of foreign threats to the US homeland. Along with the adaptation of a new model of security was a recognition of rapidly changing threats. These changes especially included those posed to critical infrastructure through cybercrime, cyberterrorism, as well as cyberwarfare. Multiple government entities have been consolidated and created to protect against cyberthreats, while legislation and directives have shaped the mission homeland security over the past 3decades. Lastly, as new cyberthreats emerge, the use of information and computer technology remains a key characteristic of cyberterrorists and cybercriminals. This chapter is an introduction to the development of homeland security, the legal framework, and the changing mission related to cybersecurity.