From the Wikipedia page 
Stockholm International Peace Research Institute (SIPRI) is an independent international institute dedicated to research into conflict, armaments, arms control and disarmament. Established in 1966, SIPRI provides data, analysis and recommendations, based on open source, to policymakers, researchers, media and the interested public.
The Foreign Policy Think Tank Index ranked SIPRI as the #3 non-U.S. think tank in the world in 2009.
In the 2011 "Global Go To Think Tanks" ranking results for non-U.S. think tanks, SIPRI was ranked #2 ,and #18 worldwide.
In 1964, Prime Minister Tage Erlander of Sweden put forward the idea of establishing a peace research institute to commemorate Sweden's 150 years of unbroken peace.
A Swedish Royal Commission chaired by Ambassador Alva Myrdal proposed in its 1966 report to establish an institute, later named the Stockholm International Peace Research Institute, SIPRI.
The Swedish Parliament decided that the Institute be established on 1 July 1966 with the legal status of an independent foundation. All SIPRI research is based exclusively on open sources.
The website is