He was Secretary of War for President Taft (1911–13) and served in World War I. While governor-general of the Philippines (1927–29) he pursued an enlightened policy of conciliation. As Secretary of State (1929–33) in the cabinet of President Hoover, he promulgated the Stimson Doctrine (or Doctrine of Non-Recognition) in response to the Japanese invasion of Manchuria (1931): a refusal to grant diplomatic recognition to actions that threatened the territorial integrity of China or violated the Kellogg-Briand Pact. He later served as Secretary of War (1940–45) under Franklin D. Roosevelt and Truman, in which post he made the recommendation to drop the atomic bomb.