Recent terrorist attacks on the sovereignty of the United States have rocked the nation's sense of security. The integrity of the U. S. air, land, and maritime borders integrity is no longer assured. Of particular concern is maritime defense and security along the extensive American coastline, especially given the volume of foreign trade. Maintaining a sea defense on a 24-hour basis for a maritime country such as the United States is both impractical and unsustainable. The best protection of our maritime borders comes from a robust intelligence gathering, synthesizing, and dissemination system. Using accurate, real time intelligence, can the nation marshal its limited maritime resources against the correct targets and establish a dynamic defense system that can deter, detect, and intercept unwanted intrusions of U.S. shorelines? This study analyzes defense of the homeland from a maritime perspective. It will also address the rising importance of Maritime Homeland Security, describe functions the Department of Defense presently performs in defending the maritime border, and assess the Coast Guard's current and future deter, detect, and intercept' role on a post-September 11th security and defense environment.