The USA and Japan had been expecting war with each other since 1900, the US had War Plan Orange which thought Japan would attack the Philippines.
Japan had the Tanaka Memorial as it is now called first published in 1927 that declared Japan's intentions to conquer all of Asia and the Pacific ocean islands including the US west coast, Panama and much of Pacific Latin America!
Japan wanted to be a world power and control all of Asia and all land that touched the Pacific and Indian Oceans. She had no resources and to get resources she was prepared to conquer the world or part of it. Also the Shinto religion demanded that Japan's emperor as the son of the Sun Goddess accept the Sun godessess mission to rule the world.
The US in contrast favored open and free trade not spheres of influence in places like China and while we did have a colony in the Philippines it was being prepared for independence, to be granted in 1944, when Japan attacked us in 1941.
Japan began to carve out colonial territories as early as 1895 in Taiwan. In 1905 She fights the ZRusso-Japanese war against Tsarist Russia and ends up with a bloody stalemate. The US brokers a peace deal called the Portsmouth Treaty which did not allow Japan nor Russia to keep their conquests in what was then called Manchuria, today north China. Both sides pull back to their pre-1905 positions. Russia did not pay Japan any money as Japan demanded and Japan kept control of Korea.
Japan saw this as a US sell out and begins planning a war to take over much of China. After WW1 when Japan fights Germany she is allowed to keep her conquests of the German colonies in China and the Central Pacific islands.
In 1932 and again in 1937 Japan embarks on a bloody war of conquest in Manchuria (1932) and China (1937) the US opposses this by diplomatic pressure and an arms build up. Both sides have been planning for a war at this point for 30 or more years. The US begins to arm the Chinese.
In June 1941 Japan occupies French Indochina to cut the Chinese supply routes, todays Laos Cambodia and Vietnam which the US has said will result in an oil and raw materials embargo. The US is Japan's biggest source of oil, we are the worlds largest oil exporter in 1941!
To Japan this sanction is the final straw and she begins war planning to start the war after the fall rice harvest is done in November-December 1941. The US moves the fleet from San Diego to Pearl Harbor.
Ok the three main causes are:
1) US desire for free trade with China directly clashes with the goals of Japan both religious and economic to create a Pacific empire and control China.
2) Japan and the US see each other as potential enemies whose differences will not be settled by diplomacy after the 1905 Portsmouth Treaty because the US rejects the idea of empire and announces it will leave the Philippines in 40 years. Japan who wishes an empire cannot allow this because to justify her claims to empire she needs the Euro-American colonial powers as a scape goat. If the US frees the Filipinos then perhaps the British might too leave India or the Dutch their colonies. Japan wants to appear as liberators to the peoples of Asia not new colonial conquerers.
3) Japan invades China and US-Japanese relations sour, the US imposes economic sanctions on Japan after she invades Indochina and Japan rather then loose face, that is be humiliated and leave Indochina and China chooses war.
No doubt there were many issues that the US had with Japan, but none of that had anything to do with the immediate attack on the US by Japan. FDR maneuvered Japan into attacking us for one reason: HE NEEDED TO GET INTO WAR WITH GERMANY IN ORDER TO SAVE BRITAIN from iminent defeat.
But once FDR knew that there had not yet been an attack on Manila by the time he had to deliver the actual message to Congress the next night, the sentence structure had to be changed from plural attacks on Manila and Hawaii to the distance of Hawaii from Japan makes it obbvious that the attack was deliberately planned many days or even weeks ago."
" THE DECISION TO BOMB "
June, 1945
During the bloody struggle to take the Philippines and Okinawa, President Truman and his military were concentrating on an invasion of Japan. The U.S. Navy was cruising off the Japanese coast and submarines were patrolling the Sea of Japan. Those in power in Tokyo were making plans for a house-to-house resistance to any invasion. Japan had over 5 million men under arms, of which 2 million were stationed on the home islands. Based upon the dogged resistance at Iwo Jima and Okinawa, the allies determined that as many as 500,000 to one million allied soldiers would die if the invasion, scheduled for November 1, 1945 took place.
U. S. President Harry S. Truman, English Prime Minister Winston Churchill, and Soviet Premier Joseph Stalin met in Potsdam, Germany between July 17 and August 2, 1945, to discuss strategies to end the war in the Pacific.
