Tripartite Pact (Germany, Italy, Japan) was concluded in September 1940. The alliance of those three states aimed, among others, also at the United States. The Japanese foreign minister, Yosuke Matsuoka (standing at the microphone), expressed it unequivocally during the meeting of the representatives of the pact in Tokyo.

On 4 August 1941 the new Japanese foreign minister, Admiral Teijiro Toyoda, appointed to that post chiefly because he belonged to an old samurai family, sent his ambassador Kichisaburo Nomura a secret dispatch. Toyoda had close connections to the financial circles of Japan, which seemed a good recommendation to America, but the text of the dispatch contradicted the apparent intentions of his job:

Commercial and economic relations between Japan and third countries, led by England and the United States, are gradually becoming so horribly strained that we cannot endure it much longer. Consequently, our Empire, to save its very life, must take measures to secure the raw materials of the South Seas. Our Empire must immediately take steps to break asunder this ever-strengthening chain of encirclement which is being woven under the guidance and with the participation of England and the United States, acting like a cunning dragon seemingly asleep. That is why we decided to obtain military bases in French Indo-China and to have our troops occupy that territory. (...)

Thus, all measures which our Empire shall take will be based upon a determination to bring about the success of the objectives of the Tripartite Pact. [Prange G. W. et al. (1991).]

After this dispatch was decoded, it landed on the desk of the US Secretary of State, Cordell Hull, who could not have any doubts about the Japanese leaders' real intentions. Especially so, that two days later Nomura, in accordance with the aforementioned directive, demanded from Hull that the United States:
  1. Remove the restrictions it had imposed upon trade with Japan.
  2. Suspend their defensive preparations in the Philippines.
  3. Discontinue furnishing military equipment to Great Britain and the Netherlands for the arming of their Far Eastern possessions.
  4. Discontinue aid to the Chinese government.
  5. Assent to Japan's assertion and exercise of a special military position and a permanent preferential political and economic status in Indochina.
In return Nomura proposed that Japan would withdraw from the French Indochina, although not before the end of the "Chinese incident"; acceptance of his proposal would effectively legalize Japanese conquests in China.

On 9 August the US president Franklin Delano Roosevelt arrived, aboard cruiser Augusta, to the Placentia Bay in Newfoundland to meet the British prime-minister Winston Spencer Churchill, who arrived there aboard battleship Prince of Wales. On the next day, after a religious service, conducted under the battleship's mighty guns, both statesmen opened talks, during which Churchill pushed for more active engagement of the United States in the Allied cause, and especially sterner policy towards Japan. Without an explicit and unequivocal declaration against the Japanese expansion, he had no hope to avoid a war between Japan and Great Britain. Churchill had even drafted the text of a note he intended to send to the Japanese to warn them of new conquests. The not had to be sent simultaneously from London and Washington.

However, while Britain had waged a war for two years then, America profited from its neutrality, and Roosevelt spoke diplomatically about a month or two he wanted to win for the British to strengthen their base in Singapore. Churchill was sure he convinced Roosevelt about a hard line against the Japanese, whose offers were coated in round words: they would take whatever was available at the moment, without giving anything in the future.

Meanwhile in Washington, Roosevelt had second thoughts about the meeting in Newfoundland, and on 17 August he invited Nomura to hand over a note, which was very much softened in comparison with Churchill's draft. In particular, any reference to a war, that might come out of the Japanese territorial expansion, were dropped. Roosevelt also discussed with Nomura a possibility of secret meeting with Prince Fumimaro Konoye in Alaska. On the next day the American ambassador in Tokyo, Joseph Grew, made more reconciliatory proposals to Toyoda.

At the end of August politicians around president Roosevelt, and Cordell Hull in particular, came to conclusion that despite of peaceful tone of the consecutive Japanese proposals for meetings and talks, their intentions were not sincere, especially in view of the intelligence reports about the Japanese military preparations. Hull had convinced Roosevelt that a meeting with Konoye had no sense without first reaching an agreement in two fundamental questions - Japanese military presence in Indochina and China. The importance of the latter was, of course, the biggest one, since a collapse of China menaced with unpredictable political and military consequences.

On the other hand, in the Japanese political circles prevailed the opinion that a compromise in China was out of question, because it would undermine the Japanese state and its concept of "Great East Asia Sphere of Co-prosperity".

For the Army spoke the minister of war, General Hideki Tojo: The army's position is that there can be no compromise on the stationing of troops in China. It affects military morale. (...) Troop withdrawals are the heart of the matter. If we just aquiesce to the American demand, everything we have achieved in China will be lost. Manchukuo will be endangered and our control of Korea will also be jeopardized.

For the Navy spoke the minister of navy, Admiral Shigetaro Shimada: On the basis of what I learned as commander of the China squadron, if our forces are removed our businessmen will have great difficulty in continuing their operations. Their personal safety may be endangered. Furthermore, no matter what happens on the mainland, I will oppose the removal of our forces from Hainan Island.

Also spoke the minister of finances, Kaya Okinori: My experience as president of the North China Development Company indicates that a troop presence is vital for our presence in China. [Ienaga S. (1978).]

Konoye's position had been gradually weakening.

During the imperial conference on 6 September 1941 the Chief of the Navy General Staff, Admiral Osami Nagano, concerned about shrinking stocks of the oil (20 million barrels on 1 April and 15 million barrels on 1 September 1941), stated:

Our Empire has not means by which to subjugate the enemy by invasion operations or to break his will to fight. Moreover, a long war is what we least desire because of the meagerness of our domestic resources. However, if we should enter into a long war, the first requisite for enduring it is to promptly occupy, at the outset, the enemy's strategic points and areas rich in natural resources, complete a solid operational setup and, at the same time, acquire from our sphere of influence vitally needed materials. If this first-stage operation should be accomplished promptly, the Empire then will be in a position to secure strategic points in the Southwest Pacific, even if military preparations of the United States develop as scheduled, and we shall be able to establish the foundation for a long war by maintaining an invincible position. [Ike N. (1967).]

The Chief of the Army General Staff, Gen. Hajime Sugiyama, defined it more precisely: In case we are unable to attain our diplomatic aims, we must immediately decide to declare war on the United States and Britain and hasten the preparations for war. Preparations must be completed by the middle of October. [Detwiler D. S., & Burdick Ch. B. (1980).]

During that conference spoke neither Konoye nor Toyoda. Perhaps they still hoped against hope that negotiations would bring any results. Or perhaps they were afraid to share the fate of many of their predecessors, whom ultra-nationalist assassins murdered amidst accusations in betraying national interests.

After the conference, Tojo and chiefs of staffs of the army and navy met with the emperor, who was seriously unsettled by the prospect of a war on all fronts. The visitors, however, convinced him that operations against the British, Dutch and American colonies in the south were thoroughly prepared and would be carried out as planned. Despite of the emperor's objections, the conference of 6 September ended in accepting the resolution:

I. Our Empire, for the purposes of self-defence and self-preservation, will complete preparations for war, with the last ten days of October as a tentative deadline, resolved to go to war with the United States, Great Britain, and the Netherlands if necessary.

II. Our Empire will concurrently take all possible diplomatic measures vis-à-vis the United States and Great Britain, and thereby endeavor to attain our objectives. The minimum objectives of our Empire to be attained through negotiations with the United States and Great Britain and the maximum concessions therein to be made by our Empire are noted in the attached documents.

III. In the event that there is no prospect of our demands being met by the first ten days of October through the diplomatic negotiations mentioned above, we will immediately decide to commence hostilities against the United States, Britain, and the Netherlands. [Ike N. (1967).]

So, the third point of the resolution had crossed all t's and dotted all i's - no agreement to satisfy Japanese demands before the mid-October meant war. The attached secret protocol, containing the minimum objectives to be attained and the maximum concessions to be made, did not promise any hopes for peaceful settlement, especially so that only five weeks were left before the deadline. And while the civilian politicians still were thinking about a way to "save face", to the navy command it was the time to complete training of the carriers' deck aircraft groups.

Despite of vigorous exchange of diplomatic notes between Tokyo and Washington, and hectic Japano-American conferences, negotiations did not bring any progress. Quite contrary, Japanese chauvinists mounted a campaign of hate against Konoye, accusing him of bargaining Japan's interests. On 18 September fanatics attempted to assassinate Konoye, who however fled to the safety of his armoured car. The next attempt was planned on the railway Tokyo - Yokosuka in case if Konoye went for a meeting with Roosevelt.

On 14 October Konoye, a man of rather weak personality, summoned all his personal will and asked the emperor permission to withdraw Japanese forces from China. However, Tojo fiercely objected. Konoye argued that it would be manifestly for Japan to plunge into an unpredictable war at a time when the "China Incident" (this is how the Japanese hypocritically called the war on China) was still unresolved. Yet Tojo had persuaded the emperor that in case of a war Japan would beat America.

Two days later Konoye resigned. In his memoirs he expressed grudge with the command of the navy: The navy would not officially say it did not want the war. The admirals would only say with great force that they 'leave all decisions to the prime minister'. [近衛文麿 (1946).]

Konoye's resentment about the admirals also came from the fact that he knew their opinions regarding possibility of winning the war, which were opposite of the opinions of Tojo and army commanders. Ten days before his resignation, the chief of the operations division of the Navy General Staff, Admiral Shigeru Fukudome, admitted that he had no confidence that Japan could win the war, and Admiral Isoroku Yamamoto, deputy minister of navy of many years, and the commander of the Combined Fleet, answered to the question of the prime minister:

If I am told to fight regardless of the consequences, I shall run wild for the first six months or year, but I have utterly no confidence for the second or third year. I hope therefore, Mr Prime Minister, that you will endeavour to avoid a Japanese-American war. [近衛文麿 (1946).]

So, despite of the lack of belief in in the sense of the new war, Japanese admirals washed their hands. Japanese historian Saburo Ienaga thus comments on the sources of their attitude:

What an incredible paradox: the admirals agreed to a war they had no confidence of winning. Fear of an army revolt if Japan backed down carried some weight with the navy leadership. Admiral Koga Mineichi found this concern misguided: "History shows that no country has been destroyed by an internal revolt. The responsible officers should have ignored the possibility of a coup d'état and courageously prevented the war. [Ienaga S. (1978).]

On 18 October Tojo formed a new government, whose intentions left no illusions to anybody. Toyoda had to resign as the foreign minister, and his post was entrusted to Shigenori Togo from an old samurai family. Tojo kept portfolio of the minister of war and interior for himself.

Of course, neither Tojo nor his closest aides ever planned a conquest of America - It was simply impossible, due to the size of the country and its distance from Japan. Their plan foresaw destruction of the American Pacific Fleet, and occupation of the areas, which would provide economical self-sufficiency to Japan. The perimeter of those areas had to be defended as long as necessary to exhaust the United States in war.

Tojo nursed the hope that the Germans would eventually win the war in Europe, eliminate the Soviet Union and cause collapse of the British Empire, while China would fall, leaving America alone, face to face with Japan. And then the strategic balance would look as follows: Japanese air forces based on land, communication and supply routes shortened, and the will to fight growing - against the American economical superiority. According to Tojo, such a balance favoured... Japan!

His calculations were guided by the notion that the country, which so far defeated all its enemies, is invincible, and irrational faith in Japan's cause, her historical mission and divine destination of the emperor. The army, and especially its command, shared that faith wholeheartedly, while their education was rather limited, and knowledge of the outer world rather meagre. Samuel Eliot Morison, an outstanding researcher of the history of the Pacific conflict, noted that Japan was the only important nation in the world in the twentieth century which combined modem industrial power and a first-class military establishment with religious and social ideas inherited from the primitive ages of mankind, which exalted the military profession and regarded war and conquest as the highest good. [Morison S. E. (2010c).]

On 10 November 1941 Admiral Yamamoto, who for three months had already been the commander of the Combined Fleet, which comprised the bulk of the Japanese naval forces, met Prince Hisaichi Terauchi, the commander of the Southern Army, an concluded with him so-called Central Agreement. It provided for destruction of principal bases of the United States, Britain and Holland in East Asia, and the occupation and security of strategic areas in the south. Areas to be occupied: Philippines, Guam, Hongkong, British Malaya, Burma, Bismarck Archipelago, Java, Sumatra, Borneo (Kalimantan), Celebes (Sulawesi) and Timor.

Before Yamamoto and Terauchi signed the Central Agreements, Japanese staffs studied four optional cases of striking southward. First case - striking first of all against the oil-rich Dutch East Indies (Indonesia) - was dismissed, although seemed very promising. A surprising and resolute attack might prevent destruction of the oil pits. Yet, in such a case Japanese sea communications would be menaced from the Philippines and Malaya. Therefore, another plan was adopted: simultaneous attack on the Philippines and Malaya, and then a concentric attack from the occupied countries on the Dutch East Indies. Two other cases evaluated neutralization of the American Pacific Fleet through a surprise attack on its bases in Hawaii.

Calculations, concerning the time needed to complete the campaign, were made as follows: Philippines - D-day + 50, Malaya - D-day + 100, and the Dutch East Indies - D-day + 150 days. There was, however, a grave provision to those plans. After a few clashes with the Japanese army in the Far East and Mongolia, the Soviet Union had deployed large forces along the Manchurian border. And as long as they were kept there, also substantial Japanese land and air forces had to be stationed in Manchuria. Together with the forces engaged in the "Chinese incident" they limited their usability for the operations in the south seas. Therefore, only 11 divisions out of 51, 700 land-based planes out of 1500, and 480 carrier-based planes were available for occupation of vast areas of the Pacific Ocean. And since the Japanese command deemed the local superiority in forces 2:1 necessary for decisive success, operational plans had to foresee use of the same units in consecutive operations.

While planning the strike in the south, a lot of attention was given to the weather factor. The Imperial Headquarters insisted that the hostilities should be open in the beginning of December, before the season of the north-east monsoon in the South China Sea and violent storms in the northern Pacific Ocean, which the Japanese fleet would have to cross en route to the Hawaii, in order to attack Pearl Harbor.

On 3 November Joseph Grew in an extended message warned Hull that war with Japan might come "with dramatic and dangerous suddenness".

The new foreign minister of Japan instructed Nomura to achieve an agreement before 25 November; the date became the new, ultimate deadline for the talks. Another diplomat was hastily dispatched to Washington to help Nomura - it was Saburo Kurusu, married to an American, and introduced in the American society. But neither he nor Nomura knew at that time that a detailed plan of a sudden attack on the Pacific Fleet had been already completed.

The Chief of Naval Operations of the US Navy, Admiral Harold Stark, who knew both Nomura and Kurusu, and was introduced in the details of the diplomatic talks, was pessimistic. On 24 November he warned American naval commanders in the Pacific Ocean that chances of favourable outcome of the negotiations with Japan were very doubtful and a "surprise aggressive movement in any direction including attack on Philippines or Guam" was a possibility.

On the next day American politicians discussed a possibility of offering the Japanese a three-months agreement on so-called modus vivendi, namely a package of provisions, which hopefully would prolong peaceful relations. However, such an agreement would have essentially sold China to Japan. Churchill had ridiculed that project, and the consultants from the interested parties, including foreign countries, had condemned it.

This way a "Far East Munich" was avoided. But since then on political negotiations became pointless. As they continued for the rest of November and into the beginning of December, Japanese naval forces were already concentrating for pending war operations. The last meeting between Nomura and Hull took place already on the first day of the war. It was short, and past without usual smiles and handshakes, since Hull already had been informed of what happened on that day in the morning in Pearl Harbor.

In 1864, before the war with Denmark, which had to award Schleswig-Holstein to Prussia, the Prussian chancellor Otto von Bismarck had created such a constellation of alliances in Europe, which fenced Prussia from third party aggression. And once he had created that system of alliances, he left the rest in the hands of his generals. In 1941 Tojo had no such dilemma, for in Japan everything was in the same hands - domestic policy, diplomacy and the armed forces. Only contrary to the war with China, where the main war effort was on the land forces, operations in the south seas and islands required the utmost engagement of the navy. It had to transport large numbers of troops and their equipment, stage complex amphibious operations, and first of all - which was an unprecedented enterprise - navy air forces had to destroy the American Pacific Fleet in its own base.

In 1941 the Imperial Japanese Navy was a great power, which possessed ships of all the classes. Only few units operated off the Chinese coasts; the rest was concentrated in the Combined Fleet, which comprised:

Carrier Striking Force
(Vice-Admiral Chuichi Nagumo)
Based in Kure, represented the biggest power in the modern naval warfare, built around ten aircraft carriers with 500 planes.
First Fleet
(Admiral Isoroku Yamamoto)
Based in Hiroshima, built around ten battleships, four heavy cruisers, and two destroyers flotillas.
Second Fleet
(Admiral Nobutake Kondo)
Based on Hainan, comprised three cruisers squadrons and two destroyers flotillas.
Third Fleet
(Vice-Admiral Ibo Takahashi)
Based on Formosa (Taiwan), designated for amphibious operations; apart of warships comprised also about 50 transports.
Fourth Fleet
(Vice-Admiral Shigeyoshi Inouye)
Based in Truk atoll for defence of the South Seas' possessions; comprised one light cruisers squadron, one destroyers squadron, 16 submarines and about 40 transports.
Fifth Fleet
(Vice-Admiral Boshiro Hosogaya)
Based on Bonin Island, auxiliary.
Sixth Fleet
(Vice-Admiral Mitsumi Shimizu)
Based in Kwajalein (Marshall Islands), about 40 submarines.

The total displacement of the Japanese fleet at the end of 1941 was 1,041,000 tons. Within nine years since the outbreak of hostilities in China (1931) till 1940, Japanese shipyards delivered ships of total displacement of 476,000t, and in 1941 - 225,000t, which included the biggest ever battleship Yamato, five aircraft-carriers and 11 submarines.

Since August 1939 the command of the Combined Fleet was in the hands of Admiral Isoroku Yamamoto - an officer, who made a long and impressive career in the navy, and had a lot of theoretical knowledge and practical experience in commanding big naval units. In Japan, as well as abroad, the had been praised as a "commander of commanders", but it does not mean that he was born for combat actions. He was rather a strategist - a person, whose personal qualities, as it has been well demonstrated by the ages of armed conflicts, are somewhat different from what is expected from an officer in direct line of duty.

In particular, Yamamoto was against a conflict with the United States, the country he had known so well from his past diplomatic service. He realised all too well that a war on two or more fronts would exceed Japan's strategic capabilities, which were limited by her natural environment. Yet, as the domestic politics had evolved towards the radical programme, as fanatics from the imperial court and the Army had been gaining upper hand in pitched disputes, and Roosevelt and Hull with their sanctions had aggravated Japan's economic troubles, Yamamoto joined the winning option. Because this is Japan - the winning option eventually gains support of all the parties, regardless of their opinions in the past. So, Yamamoto had engaged all his energy, skills and knowledge in the cause, which provided for simultaneous attack on the American, British and Dutch possessions in vast spaces of the Pacific Ocean and adjacent seas.