For defense related publications, two resources to try are the Defense Technical Information Center (DTIC) and Homeland Security Digital Library (HSDL).
DTIC provides citations and access to an extensive database of technical reports related to defense research interestes. It also features a scientific and technical (S&T) collection which covers all areas of defense research, including biological and medical science, environmental pollution and control, and behavioral and social science. The collection also contains Department of Defense (DoD) directives and instructions, budget information, conference and symposia proceedings, patents and patent applications, and other topics of interest to the defense community.
For those titles which are available online, a direct link is provided.
LRC users enjoy access to the HSDL's full collection of over 130,900 resources. These resources come from the U.S. federal, state, and local governments, international governments and institutions, nonprofit organizations and private sector entities, think tanks, research centers, and colleges and universities.