The events of September 11 2001, led to profound changes in government policies and structures to confront homeland security threats. Most notably, the Department of Homeland Security (DHS) began operations in 2003 with key missions that included preventing terrorist attacks from occurring in the U.S., and minimising the damages from any attacks that may occur. This book examines DHS's progress in implementing its homeland security missions since it began operations; work remaining and issues affecting implementation efforts.