Vietnam, Consensus, and the Belief Systems of American Leaders 
A er the Japanese attack on Pearl Harbor in 1941, Senator Arthur Vandenberg wrote, “In my own mind, my convictions regarding international cooperation and collective security for peace took rm form on the a ernoon of the Pearl Harbor attack. at day ended isolationism for any realist.”2 e leading spokesman for American isolationism thus acknowledged that the disaster in Hawaii was of such signi cance as to reshape his core beliefs about international politics and the proper American response to a rapidly changing world. e impact of such events as Pearl Harbor did not vanish with the destruction of the Paci c Fleet-or even with the end of World War II. It lived on in the minds of Vandenberg and many of his contemporaries as a symbol of the futility of isolationism, and continued to have a deep in uence on the conduct of American diplomacy. Indeed, not until a generation later, with the United States mired in a seemingly endless war in Southeast Asia, did some of the “lessons” of Pearl Harbor and other events leading up to World War II come under sustained challenge by informed and thoughtful critics.