On this day in 1941, Adm. Harold R. Stark, U.S. chief of naval operations, tells Adm. Husband E. Kimmel, commander of the U.S. Pacific Fleet at Pearl Harbor, that both President Roosevelt and Secretary of State Cordell Hull think a Japanese surprise attack is a distinct possibility.
"We are likely to be attacked next Monday, for the Japs are notorious for attacking without warning," Roosevelt had informed his Cabinet. "We must all prepare for trouble, possibly soon," he telegraphed British Prime Minister Winston Churchill.
Kimmel's command was specifically at the mid-Pacific base at Oahu, which comprised, in part, Pearl Harbor. At the time he received the "warning" from Stark, he was negotiating with Army Lt. Gen. Walter C. Short, commander of all U.S. forces at Pearl Harbor, about sending U.S. warships out from Pearl Harbor in order to reinforce Wake and Midway Islands, which, along with the Philippines, were possible Japanese targets. But the Army had no antiaircraft artillery to spare.
War worries had struck because of an intercepted Japanese diplomatic message, which gave November 25 as a deadline of sorts. If Japanese diplomacy had failed to convince the Americans to revoke the economic sanctions against Japan, "things will automatically begin to happen," the message related. Those "things" were becoming obvious, in the form of Japanese troop movements off Formosa (Taiwan) apparently toward Malaya. In fact, they were headed for Pearl Harbor, as was the Japanese First Air Fleet.
Despite the fact that so many in positions of command anticipated a Japanese attack, especially given the failure of diplomacy (Japan refused U.S. demands to withdraw from both the Axis pact and occupied territories in China and Indochina), no one expected Hawaii as the target.
Taken from: http://www.history.com/this-day-in-history/a-war-warning-is-sent-to-commanders-in-the-pacific [25.11.2014]