On August 7, 1936, the Hirota Hiroki cabinet proposed Japan's "national policy standards," which decided to "secure the empire's position on the East Asian continent in both foreign and defense aspects, and at the same time expand and develop in the southern maritime area," that is, to make "southward expansion" and "northward expansion" as national policy. In order to achieve the "national policy benchmark", Japan first invaded China and made a breakthrough in the middle, but it was trapped in the Chinese battlefield and unable to extricate itself. In 1938 and 1939, Japan used troops against the Soviet Union, but the results ended in failure, and the "northward advance" strategy was impacted.

At that time, the international situation had changed dramatically, and in the summer of 1940, Germany succeeded in blitzing Western Europe, the Netherlands and France were defeated one after another, and Britain was also in danger. On April 15, 1940, Foreign Minister Arita issued a statement declaring that Japan was inextricably linked with the countries of Southeast Asia and the South Seas region, and that Japan "cannot ignore any changes in this region." On June 29, he delivered a speech on the so-called "Building a New Order in Greater East Asia." On July 26, the Second Konoe Cabinet threw out the "Outline of Basic National Policy" and formulated the "Outline for Handling the Current Situation to Adapt to the Evolution of the World Situation", declaring that the fundamental policy of Japan ** is to "believe" that in the war in Europe, the old forces are succumbing to the power of the emerging powers, and only Britain is left to survive, and the world situation is changing quite dramatically. The opportunity to establish self-sufficiency in the South Seas east of India and north of Australia and New Zealand will never be the same as today." On August 1, Foreign Minister Yoyoshi Matsuoka officially put forward the slogan of establishing a "Greater East Asia Co-Prosperity Sphere" in his first speech after taking office. The intention of this move is, firstly, to provide a huge and reliable market and a stable source of raw materials for Japan's manufacturing industry economically; Second, militarily, the Blocking Alliance proposed to turn Southeast Asia and the western Pacific region into Japanese colonies, and then establish a "self-sufficient" economic system. In mid-December 1940, a military research department was established in Taiwan Province of China, which was responsible for "the investigation of military intelligence and the geography of military information in various parts of the south." In the same month, the South China Front was ordered to conduct tropical and landing combat training for its subordinate units. In March ~ April of the following year, the Japanese base camp conducted a joint exercise of actual forces of land, sea and air forces after the hypothetical occupation of Malaya and continued to capture Singapore, and conducted long-distance sea flights (including night flights) and communication and liaison training for the air force, and created an airborne unit in September 1941.

Japan is extremely poor in resources, and most of its main strategic resources rely on imports, while Southeast Asia is rich in resources, especially "the Dutch East Indies is the oil treasure house of East Asia, with an annual production of about 8 million tons, which is 20 times that of Japan." At that time, Japan needed about 5 million tons of oil per year, and its self-sufficiency capacity was less than one-tenth", the geographical location of Southeast Asia was very important, and the occupation of Southeast Asia could not only cut off the two important communication lines of the United States and Britain and other countries to aid China: the Yunnan-Vietnam Railway and the Yunnan-Burma Highway, but also enter the Indian Ocean to the west to threaten India, and join forces with the German army in the Middle East, and to the south could capture Australia and dominate the Western Pacific.

Since Matthew Perry's "visit" to Japan in 1853, which opened a new page in Japan-US relations, until the Spanish-American War, Japan-US relations have been relatively peaceful. The victor of the Spanish-American War, the United States and Japan, the victor of the Sino-Japanese War, began the struggle for hegemony in China and the Pacific region at the end of the 19th century.

After the Russo-Japanese War, Japan's influence in Northeast China increased greatly, and relations between Japan and the United States took a sharp turn for the worse, and both sides began to regard the other as imaginary enemies. On January 2, 1917, Ishii, the representative of Japan, and U.S. Secretary of State Lansing signed the Ishii-Lansing Agreement on the China question. In the agreement, the United States recognized Japan's "special rights" in China, especially in South Manchuria, but reminded Japan that it must not dominate China and must ensure that China's doors are open and that opportunities for industry and commerce in all countries must be guaranteed.

From November 1921 to February of the following year, Washington, the capital of the United States, held a nine-nation naval disarmament conference and a Washington conference on the Far East question, attended by the United States, Britain, Japan, France, Italy, Portugal, Belgium, the Netherlands, and China. The "Nine-Power Pact" proclaimed the principle of "open door" and "equal opportunity" for all countries in China, and Japan handed over the rights and interests of the former Germany in Shandong, China. The Washington Conference, which ended in a U.S. victory, made the contradictions between Japan and the United States public, and intensified the contradictions between the United States and Japan in the Far East and the Pacific. In February 1923, when Japan revised its imperial defense policy, it listed the United States as the first imaginary enemy country in light of the international situation at that time.

After the September 18 incident, the contradictions between Japan and the United States further developed, and in 1934, Japan announced the abolition of the Naval Armaments Treaty, and in January 1936, it withdrew from the London Disarmament Conference. Japan's secession from the Washington and London treaties severely impacted the Versailles-Washington system, which meant that the contradictions between Japan and the United States and European powers began to intensify. In 1940, the "Treaty of the Triple Alliance between Germany, Italy and Japan" was signed in Berlin, which seriously deteriorated the strategic position and strategic environment of the United States. As a result, a year before the outbreak of the Pacific War, the United States took three interrelated actions in the Asia-Pacific region: stepped up assistance to China in the war of resistance; tightening economic sanctions against Japan; Negotiations with Japan began. Such hard and soft hands constituted the actual content of the US Far East strategy at that time.

Germany's success in blitzkrieg in Western Europe caused European and American imperialism to devote its main energies to the European theater and had no time to look eastward, creating a "vacuum" in the skies over Southeast Asia and giving Japanese imperialism an opportunity to take advantage of. Japan changed its previous wait-and-see hesitation to sign the German-Italian-Japanese Triple Alliance, and on September 27, 1940, the Treaty of the German-Italian-Japanese Triple Alliance was signed in Berlin. It has realized the basic policy of Japanese imperialism of "adapting to the sudden changes in the world situation, rapidly building a new order in East Asia, and seeking to strengthen the axis of Japan, Germany, and Italy."

The contradictions between the United States and Britain and Japan in the Far East have a long history, and in particular, Japan's launching of a full-scale war of aggression against China has seriously damaged the economic interests of the United States and Britain in China. However, due to the increasingly tense situation in Europe, the decline of Britain's comprehensive national strength, and the powerful isolationist forces in the United States, they tried their best to avoid conflict with Japan in the Far East in a vain attempt to "obtain Japan's concessions at the expense of China's interests and achieve a conditional compromise between the two sides, so as to preserve the basic interests of Western countries in China." Under the guidance of this ideology, the United States and Britain adopted a policy of appeasement of compromise and concession toward Japan. In handling the issue of relations with Japan, Britain has tried to push the United States to the front line to deal with the crisis. As a sign of sincerity, Britain also signed the "Aritta-Claeon Agreement" with Japan, which "recognized Japan's special status in China and the responsibility of the Japanese army to maintain law and order in the occupied areas."

After the "918" incident, the United States continued to increase its trade with Japan, especially the export of strategic raw materials to Japan, despite Japan's ever-expanding aggression. After 1932 and before the "77 Incident," the United States supplied 90 percent of Japan's imports of scrap steel, 65 percent of oil and petroleum products, 90 percent of copper and 45 percent of lead, and 70 percent of the machine tools necessary for the expansion of the military industry. In 1937, the United States exported a total of $288,558,000 of materials to Japan, of which war materials accounted for 58%; In 1938, a total of 239.575 million US dollars of materials were exported to Japan, of which war materials accounted for 67%; In 1939, 90% of Japan's oil imports came from the United States.

The appeasement policy pursued by the United States and Britain fueled Japan's ambitions and accelerated the pace of Japan's launching of the Pacific War. After the outbreak of the war in Europe, Japan took advantage of the defeat of France and the British siege of the British Isles, and forced them to close the Yunnan-Vietnam Railway and the Yunnan-Burma Highway, and forcibly stationed themselves in northern Indochina in September, taking the first step in seizing European and American colonies in Southeast Asia by force. In July 1941, it forcibly stationed itself in southern Indochina and forced France to sign the "Japan-France Protocol on the Mutual Defense of Indochina", thus controlling the naval bases of Saigon and Cam Ranh Bay, and turning Indochina into a strategic base and logistics base for the realization of its "southward expansion" plan.

Germany's success in blitzkrieg in Western Europe caused European and American imperialism to devote its main energies to the European theater and had no time to look eastward, creating a "vacuum" in the skies over Southeast Asia and giving Japanese imperialism an opportunity to take advantage of. Japan changed its previous wait-and-see hesitation to sign the German-Italian-Japanese Triple Alliance, and on September 27, 1940, the Treaty of the German-Italian-Japanese Triple Alliance was signed in Berlin. It has realized the basic policy of Japanese imperialism of "adapting to the sudden changes in the world situation, rapidly building a new order in East Asia, and seeking to strengthen the axis of Japan, Germany, and Italy."

The contradictions between the United States and Britain and Japan in the Far East have a long history, and in particular, Japan's launching of a full-scale war of aggression against China has seriously damaged the economic interests of the United States and Britain in China. However, due to the increasing tensions in Europe, the decline of Britain's overall national strength, and the strong isolationist forces in the United States, they tried to avoid conflict with Japan in the Far East, in a vain attempt to "achieve a conditional compromise between the two sides at the expense of China's interests, so as to preserve the basic interests of Western countries in China" [21] . Under the guidance of this ideology, the United States and Britain adopted a policy of appeasement of compromise and concession toward Japan. In handling the issue of relations with Japan, Britain has tried to push the United States to the front line to deal with the crisis. As a sign of sincerity, Britain also signed the "Aritta-Claeon Agreement" with Japan, which "recognized Japan's special status in China and the responsibility of the Japanese army to maintain law and order in the occupied areas."

"After Japan's occupation of Southeast Asia, the United States' trade with Japan, especially the export of strategic raw materials to Japan, continued to increase in the face of Japan's expanding aggression. After 1932 and before the Southern Incident, the United States supplied 90 percent of Japan's imports of scrap steel, 65 percent of oil and petroleum products, 90 percent of copper and 45 percent of lead, and 70 percent of the machine tools necessary to expand the military industry. In 1937, the United States exported a total of $288,558,000 of materials to Japan, of which war materials accounted for 58%; In 1938, a total of 239.575 million US dollars of materials were exported to Japan, of which war materials accounted for 67%; In 1939, 90% of Japan's oil imports came from the United States.

The appeasement policy pursued by the United States and Britain fueled Japan's ambitions and accelerated the pace of Japan's launching of the Pacific War. After the outbreak of the war in Europe, Japan took advantage of the defeat of France and the British siege of the British Isles, and forced them to close the Yunnan-Vietnam Railway and the Yunnan-Burma Highway, and forcibly stationed themselves in northern Indochina in September, taking the first step in seizing European and American colonies in Southeast Asia by force. In July 1941, it forcibly stationed itself in southern Indochina and forced France to sign the "Japan-France Protocol on the Mutual Defense of Indochina", thus controlling the naval bases of Saigon and Cam Ranh Bay, and turning Indochina into a strategic base and logistics base for the realization of its "southward expansion" plan.

Before the outbreak of the Pacific War, China and Britain had realized the importance of Burma's strategic location and the possibility of being attacked by Japan, and began to plan a common defense plan, and signed the "Sino-British Agreement on the Mutual Defense of the Yunnan-Burma Road" on December 23, 1940, but Britain refused to allow Chinese troops to enter Burma on the grounds that "a formal alliance is sufficient to ensure the security of Burma" in the early days of the Pacific War, and it was not until February 1941 that Britain realized that it could not guarantee the security of Burma by its own strength. Ask the Chinese army to fight in Burma.

In the face of Japan's imminent aggression, the United States and Britain have adopted corresponding economic sanctions against Japan. On July 26, 1940, the United States announced the imposition of a "moral embargo", "export license", "economic embargo" and other measures against Japan, and after Japan entered Indochina, it imposed a scrap steel export license system on Japan, and Britain also reopened the Yunnan-Burma Highway on October 18 and began to transport supplies to China. On July 28, 1941, the United States and Britain froze Japanese capital in the United States and Britain, which was "the first time since Japan began its aggression and expansion in 1931 that the two countries took measures to resist Japan's aggression, and it was the first coordinated action between the two countries." However, from these sanctions, the United States and Britain are still reluctant to provoke Japan too much, especially the absence of an embargo on oil. On July 26, 1940 ~ January 15, 1941, the United States signed a 7 million barrel oil export license with Japan, of which 3 million barrels of oil have been imported into Japan, accounting for 1/3 of the average export rate in 1936~1939. Until August 1, 1941,

The United States announced an oil embargo on Japan, and in September the United States and Britain stopped all trade with Japan.