The Brookings Institution is "one of Washington's oldest think tanks, is an independent, nonpartisan organization devoted to research, analysis, and public education with an emphasis on economics, foreign policy, governance, and metropolitan policy."
http://www.brookings.org

The RAND Corporation "is a nonprofit research organization providing objective analysis and effective solutions that address the challenges facing the public and private sectors around the world."
http://rand.org/

The Center for Strategic and International Studies (CSIS) is "dedicated to providing world leaders with strategic insights on — and policy solutions to — current and emerging global issues."
http://www.csis.org/

The Center for Strategic and Budgetary Assessments (CSBA) "is an independent, nonprofit public policy research institute established to promote innovative thinking about defense planning and investment strategies for the 21st century."
http://www.csbaonline.org

The CNA Corporation "is a non-profit organization that during World War II pioneered the field of operations analysis...more than half-a-century of experience researching and analyzing the complex scientific, operational, and policy challenges that are facing the public sector and public decision makers."
http://www.cna.org/

The Heritage Foundation "is a research and educational institute - a think tank - whose mission is to formulate and promote conservative public policies based on the principles of free enterprise, limited government, individual freedom, traditional American values, and a strong national defense."
http://www.heritage.org/

The National Institute for Public Policy "is a non-profit public education organization that focuses on a wide spectrum of rapidly evolving foreign policy and international issues."
http://www.nipp.org/

The Paul H. Nitze School of Advanced International Studies (SAIS), a division of Johns Hopkins University, "is a leading graduate school of international affairs, educating students for professional careers in government, business, journalism, international law and non-profit organizations."
http://www.sais-jhu.edu/

U.S. Army War College Strategic Studies Institute (SSI) "is the U.S. Army's institute for geostrategic and national security research and analysis. SSI's primary function is to provide direct analysis for Army and Department of Defense leadership, and serve as a bridge to the wider strategic community."
http://www.StrategicStudiesInstitute.army.mil

The Center for Naval Warfare Studies was established within the Naval War College "as a nexus for broadly based, advanced research on the naval contribution to a national strategy."
http://www.nwc.navy.mil/cnws/

The Center for Strategy and Technology at the Air War College engages in long-term strategic thinking about technology and its implications for U.S. national security.
http://csat.au.af.mil/

The National Defense University educates military and civilian leaders through teaching, research, and outreach in national security strategy, national military strategy, and national resource strategy; joint and multinational operations; information strategies, operations, and resource management; acquisition; and regional defense and security studies.
http://www.ndu.edu/