<P> Japan and the U.S. engaged in negotiations during the course of 1941 in an effort to improve relations . During these negotiations, Japan offered to withdraw from most of China and Indochina when peace was made with the Nationalist government, adopt an independent interpretation of the Tripartite Pact, and not to discriminate in trade provided all other countries reciprocated . Washington rejected these proposals . Japanese Prime Minister Konoye then offered to meet with Roosevelt, but Roosevelt insisted on coming to an agreement before any meeting . The U.S. ambassador to Japan repeatedly urged Roosevelt to accept the meeting, warning that it was the only way to preserve the conciliatory Konoye government and peace in the Pacific . His recommendation was not acted upon . The Konoye government collapsed the following month when the Japanese military refused to agree to the withdrawal of all troops from China . </P> <P> Japan's final proposal, on November 20, offered to withdraw their forces from southern Indochina and not to launch any attacks in Southeast Asia provided that the U.S., the UK, and the Netherlands ceased aiding China and lifted their sanctions against Japan . The American counter-proposal of November 26 (November 27 in Japan) (the Hull note) required Japan to evacuate all of China without conditions and conclude non-aggression pacts with Pacific powers . However the day before the Hull Note was delivered, on November 26 in Japan, the main Japanese attack fleet left port for Pearl Harbor . </P> <P> Preliminary planning for an attack on Pearl Harbor to protect the move into the "Southern Resource Area" (the Japanese term for the Dutch East Indies and Southeast Asia generally) had begun very early in 1941 under the auspices of Admiral Isoroku Yamamoto, then commanding Japan's Combined Fleet . He won assent to formal planning and training for an attack from the Imperial Japanese Navy General Staff only after much contention with Naval Headquarters, including a threat to resign his command . Full - scale planning was underway by early spring 1941, primarily by Rear Admiral Ryūnosuke Kusaka, with assistance from Captain Minoru Genda and Yamamoto's Deputy Chief of Staff, Captain Kameto Kuroshima . The planners studied the 1940 British air attack on the Italian fleet at Taranto intensively . </P> <P> Over the next several months, pilots were trained, equipment was adapted, and intelligence was collected . Despite these preparations, Emperor Hirohito did not approve the attack plan until November 5, after the third of four Imperial Conferences called to consider the matter . Final authorization was not given by the emperor until December 1, after a majority of Japanese leaders advised him the "Hull Note" would "destroy the fruits of the China incident, endanger Manchukuo and undermine Japanese control of Korea ." </P>

When did japan start planning the attack on pearl harbor