Stanley Kuhl Hornbeck (May 4, 1883 – December 10, 1966) was a diplomat, born in Franklin, Massachusetts. A Rhodes scholar and the author of eight books, he had a distinguished career in government service. He was chief of the State Department Division of Far Eastern Affairs (1928–1937), a special adviser to Secretary of State Cordell Hull (1937–1944), and ambassador to The Netherlands (1944–1947).
In November 1941, contemptuous of the Japanese capacity to challenge US strength, Hornbeck dismissed the fears of a young Foreign Service officer, Charles W. Yost, that Japan might initiate war out of desperation over the oil embargo imposed by the United States. Then, ten days before the attack on Pearl Harbor, after drafting with Secretary of State Cordell Hull a hardline memo laying down conditions for relaxation of the sanctions, Hornbeck wagered that Japan would relent and that war was not imminent. The note that Hull sent the Japanese on November 26, 1941, said that Japan would have to withdraw from Southeast Asia and China before the United States would resume the oil shipments. Confident that his tough approach would cause Japan to back down, Hornbeck wrote in a memorandum the following day:
For more than a decade, Hornbeck had urged the United States to pursue a policy of economic pressure on Japan. Although Hornbeck had been derided by historians for his ill-founded wager, some observers argue that he understood as well as any other US policymaker at the time the irreconcilable conflict between Japan and US interests. Some observers believe that had his recommendations been followed much earlier, Japanese power would have been significantly weakened.