<P> Japanese records, admitted into evidence during congressional hearings on the attack after the war, established that Japan had not even written a declaration of war until hearing news of the successful attack . The two - line declaration was finally delivered to U.S. ambassador Grew in Tokyo about ten hours after the completion of the attack . Grew was allowed to transmit it to the United States, where it was received late Monday afternoon (Washington time). </P> <P> In July 1941, IJN headquarters informed Emperor Hirohito its reserve bunker oil would be exhausted within two years if a new source was not found . In August 1941, Japanese prime minister Fumimaro Konoe proposed a summit with President Roosevelt to discuss differences . Roosevelt replied Japan must leave China before a summit meeting could be held . On September 6, 1941, at the second Imperial Conference concerning attacks on the Western colonies in Asia and Hawaii, Japanese leaders met to consider the attack plans prepared by Imperial General Headquarters . The summit occurred one day after the emperor had reprimanded General Hajime Sugiyama, chief of the IJA General Staff, about the lack of success in China and the speculated low chances of victory against the United States, the British Empire and their allies . </P> <P> Prime Minister Konoe argued for more negotiations and possible concessions to avert war . However, military leaders such as Sugiyama, Minister of War General Hideki Tōjō, and chief of the IJN General Staff Fleet Admiral Osami Nagano asserted time had run out and that additional negotiations would be pointless . They urged swift military actions against all American and European colonies in Southeast Asia and Hawaii . Tōjō argued that yielding to the American demand to withdraw troops would wipe out all the gains of the Second Sino - Japanese War, depress Army morale, endanger Manchukuo and jeopardize control of Korea; hence, doing nothing was the same as defeat and a loss of face . </P> <P> On October 16, 1941, Konoe resigned and proposed Prince Naruhiko Higashikuni, who was also the choice of the army and navy, as his successor . Hirohito chose Hideki Tōjō instead, worried (as he told Konoe) about having the Imperial House being held responsible for a war against Western powers . </P>

What factors led japan to attack the united states at pearl harbor