Events Leading To The Attack On Pearl Harbor - Background To Conflict

Background To Conflict

Tensions between Japan and the prominent Western countries (the United States, France, Britain, and the Netherlands) increased significantly at the beginning of the increasingly militaristic Showa era, as Japanese nationalists and military leaders exerted increasing influence over government policy, adopting creation of a Greater East Asia Co-Prosperity Sphere as part of Japan's alleged "divine right" to unify Asia under Emperor Hirohito's rule, threatening already-established American, French, British, and Dutch colonies in Asia.

Over the course of the 1930s, Japan's increasingly expansionist policies brought it into renewed conflict with its neighbors, Russia and China (Japan had fought the First Sino-Japanese War with China in 1894-95 and the Russo-Japanese War with Russia in 1904-05; Japan's imperialist ambitions had a hand in precipitating both conflicts). In March 1933, Japan withdrew from the League of Nations in response to international condemnation of its conquest of Manchuria and subsequent establishment of the Manchukuo puppet government. On January 15, 1936, Japan withdrew from the Second London Naval Disarmament Conference because the United States and Great Britain refused to grant the Imperial Japanese Navy (IJN) parity with their navies. A second full-scale war between Japan and China began with the Marco Polo Bridge Incident in July 1937.

Japan's 1937 attack on China was condemned by the U.S. and several members of the League of Nations including Britain, France, Australia, and the Netherlands. Japanese atrocities during the conflict such as the Rape of Nanking, served to further complicate relations with the rest of the world. These states had economic and territorial interests, or formal colonies, in East and Southeast Asia; they were increasingly alarmed at Japan's new military power and its willingness to use it, which threatened their control in Asia. In July 1939, the U.S. terminated its 1911 commercial treaty with Japan. These efforts failed to deter Japan from continuing its war in China, or from signing the Tripartite Pact in 1940 with Nazi Germany and Fascist Italy, officially forming the Axis Powers.

Japan would take advantage of Hitler's war in Europe to advance its ambitions in the Far East. The Tripartite Pact guaranteed assistance if a signatory was attacked by any country not already involved in their conflicts. (This implicitly meant the U.S.) By joining it, Japan simultaneously gained geo-political power, and it sent the unmistakable message any U.S. military intervention risked war on both of her shores—with Germany and Italy on the Atlantic, and with Japan on the Pacific. The Roosevelt administration would not be dissuaded. Believing the American way of life would be endangered if Europe and the Far East fell under military dictatorship, it committed to help the British and Chinese through loans of money and materiel, and pledged sufficient continuing aid to ensure their survival. Thus, the United States slowly moved from being a neutral to one preparing for war.

On October 8, 1940, Admiral James O. Richardson, Commander in Chief, Pacific Fleet, provoked a confrontation with Roosevelt by repeating his earlier arguments to Chief of Naval Operations Admiral Harold R. Stark and Secretary of the Navy Frank Knox that Pearl Harbor was the wrong place for his ships. Roosevelt believed relocating the fleet to Hawaii would exert a "restraining influence" on Japan.

Richardson asked the President if the United States was going to war. Roosevelt's view was:

"At least as early as October 8, 1940, ...affairs had reached such a state that the United States would become involved in a war with Japan. ... 'that if the Japanese attacked Thailand, or the Kra Peninsula, or the Dutch East Indies we would not enter the war, that if they even attacked the Philippines he doubted whether we would enter the war, but that they (the Japanese) could not always avoid making mistakes and that as the war continued and that area of operations expanded sooner of later they would make a mistake and we would enter the war.' ... ".

Japan's 1940 move into Vichy-controlled Indochina further raised tensions. When combined with its war with China, withdrawal from the League of Nations, alliance with Germany and Italy, and increasing militarization, the move provoked an attempt to restrain Japan economically. The United States embargoed scrap metal shipments to Japan and closed the Panama Canal to Japanese shipping. In early 1941, Japan moved into southern Indochina. thereby threatening British Malaya, North Borneo, and Brunei. The U.S. responded by freezing Japanese assets in the U.S. on 26 July 1941 and by embargoing oil and gasoline exports to Japan six days later. The oil embargo was an especially strong response because oil was Japan's most crucial import, and more than 80 percent of Japan's oil at the time came from the United States. Japanese war planners had long looked south, especially to Brunei for oil and to Malaya for rubber and tin. The Navy was (mistakenly) certain any attempt to seize this region would bring the U.S. into the war, but the complete U.S. oil embargo removed any hesitancy. Moreover, any southern operation would be vulnerable to attack from the Philippines, then a U.S. commonwealth, so war with the U.S. seemed necessary in any case.

After the embargoes and the asset freezes, the Japanese Ambassador to Washington, Kichisaburō Nomura, and U.S. Secretary of State Cordell Hull held multiple meetings in order to resolve Japanese-American relations. But no solution could be agreed upon for three key reasons:

1. Japan's alliance to Hitler's Germany and Mussolini's Italy through the Tripartite Pact;
2. Japan wanted economic control and responsibility for southeast Asia;
3. Japan refused to leave mainland China (without Manchoukuo).

The U.S. embargoes gave Japan a sense of urgency. It would either have to agree to Washington's demands or use force to gain access to the resources it needed.