Robert Strange McNamara (June 9, 1916 – July 6, 2009), also known by his initials RSM, was an American businessman and government official who served as the eighth United States secretary of defense from 1961 to 1968 under presidents John F. Kennedy and Lyndon B. Johnson at the height of the Cold War. He remains the longest-serving secretary of defense, having remained in office over seven years. He played a major role in promoting the U.S. involvement in the Vietnam War. McNamara was responsible for the institution of systems analysis in public policy, which developed into the discipline known today as policy analysis.