The Sigma Series of ''War Games'' were Top-Secret US Department of Defense and Pentagon simulations – designed to give various projections to ''how'' a War in Southeast Asia (Vietnam) would go. Various scenarios were ''played'', including the use of limited Nuclear assets. The ''Game'' was played by US Army Senior Officers, portraying Enemy ''sides''. Starting in 1962. many of Sigma's scenarios would come true, especially with regards to America' early involvement in Vietnam (1964-1966). However, most casualty ratios were much higher than anticipated. (9) separate Games were played, ending in 1972. Several scenarios also took into accounts American Society and their response to a so-called ''Losing War''. The Sigma accurately projected anti-Draft Riots and other Social disturbances at the time (Civil Rights Movement). Sigma never projected a clear ''win'' by US or Allied Forces engaged in The Vietnam War. Other scenarios played involved indirect and direct combat with Communist China and Soviet Russia, both of whom were supplying war materials to The NVA and VC Forces. These scenarios ended with full scale Nuclear War at some point. Sigma made it very ''clear'' that a protracted War in Southeast Asia would eventually lead to Nuclear Combat. The very existence of Sigma was kept secret until The National Freedom of Information Act of 1974.