|| The Country Indicators for Foreign Policy provides measures of domestic armed conflict, governance and political instability, militarization, religious and ethnic diversity, demographic stress, economic performance, human development, environmental stress, and international linkages.
|| The Correlates of War project seeks to facilitate the collection, dissemination, and use of accurate and reliable quantitative data in international relations. Free datasets.
||The Group for Research and Information on Peace and Security studies European defense and security, the prevention and resolution of African conflicts, arms races, and a host of other topics. Site is in French.
||The Institute for International Security Studies publishes The Military Balance, an assessment of the military capabilities and defense economies of 170 countries.
||The International Peace Research Institute is the oldest peace research institute in the world. Centre for the Study of Civil War.
||The Stockholm International Peace Research Institute conducts research on questions of conflict and cooperation of importance for international peace and security. Extensive military expenditure data by country.
||The World Military and Arms Transfers, published by the US State Department's Bureau of Verification and Compliance. Has not been updated since 2000.