Why did they attack Peal Harbor instead of say, Paris or Saint Petersburg? The US weren't participating in WW2 yet, so why attack a small threat?
Not directly, but by Japanese calculations, they'd have to face the US sooner or later. u/jschooltiger goes into the direct reasons here, which also links to u/ParkSungJun's earlier analysis of why Japan was undergoing a resource shortage.
Also, while I realise it's a bit tangential to your real question, your alternative targets would have been much, much harder for the Japanese to hit than Pearl Harbor. The attack itself was already on the edge of Japanese logistical capability, to the point where early plans seriously considered the notion of abandoning whichever carriers didn't have enough fuel to make it back. Indeed, only three of the six carriers of Kido Butai had the unmodified capability to make it from Japan to Hawaii and back without refueling. The mind boggles at trying to strike a target much more distant than Pearl. (Not to mention that by this time, Paris was already under German occupation for a year and a half.)
Greetings! This week seems to be filled with questions on Japan in World War II, and I'm not complaining! Alongside the excellent responses (tangential or linked) in u/DanKensington's comment and the crucially helpful aside by u/DBHT14, I would like to give a longer response based on a similar question I answered on the sub. Let's begin.
Plan North or South?
Adapted from an earlier response I made on the interwar politics of Japan, worth a read if you are interested.
In January of 1939, Prime Minister (and Prince) Fumimaro Konoe resigned his government position over the failure of the Japanese army to break the stalemate which had developed in China. He was followed by three men over the next eighteen months: right-wing bureaucrat Hiranuma Kiichiro, General Abe Nobuyuki, and Admiral Yonai Mitsumasa. All three had a clear problem on their hands: Japan was already bogged down in continental war with China, but the government (heavily influenced by the military) was well aware that further threats surrounding the island nation. To the north was the Soviet Union, a nation which Japan had sought to prevent from existing by dispatching troops to fight against the Reds in the Russian Civil War. To the south and across the Pacific were Britain and the United States respectively, each fielding powerful navies which threatened the IJN’s own fleets. There was no question that Japan’s warpath would eventually set it against all four of these threats. But as R.A.C Parker notes, the internal debate was on:
“[T]iming and priorities; how far existing resources should be first developed, how far and to where they should be extended, which threats should first be countered and when.”
Within this sphere of geopolitical debate, we have the emergence of two key ‘schools’. The first were the proponents of the Hokushin-ron (Northern Expansion Doctrine), which believed that the Soviet Union and its Siberian regions were the next prime target for Japan’s expansion. Prominent members of this group included PM Hiranuma himself, officers in the IJA, and war minister Seishiro Itagaki. Opposing them were the proponents of the Nanshin-ron (Southern Expansion Doctrine), which believed that the European colonies of British Malaya and the Dutch East Indies were the next prime targets for Japan’s expansion. Prominent members in this group included PM and former navy minister Yonai Mitsumasa, as well as admirals in the IJN.7 This army-navy dichotomy is actually a theme that has occurred before in Japan’s political discourse, so I shall quote Andrew Gordon here on the usual split between the IJN and IJA.
“The army saw the greatest threat to Japan’s Asian hegemony—and the greatest opportunities to solve the problem—residing in China, especially North China and Manchuria. The navy focused its concerns on rival Western powers in the Pacific.”
Both directions of expansion also had their problems, and it was these considerations alongside Japan’s reaction to external events which would ultimately sway the direction of the government. For Hokushin-ron, Japanese forces had lost the disastrous Nomonhan Incident, otherwise known as the “Battle of Khalkhin Gol” with the Soviet Union. This border skirmish took place in May of 1939, and it cost the Kwantung Army some 12,000 men dead or wounded. In addition to the German betrayal of Japan following the signing of the Molotov-Ribbentrop Pact, caused Tokyo to shift critically towards Nanshin-ron. Historian Owen Matthews on the significance of Nomonhan:
“The humiliation of the Kwangtung Army strengthened the hand of the ‘South Strike’ [Nanshin-ron] Group - led by the navy - who argued for Japan to attack its Asian neighbors and leave the USSR alone. The Japanese reluctance to risk another trouncing at the hands of the Red Army would become a major factor in the outcome of the coming world war.”
Mind you, Tokyo also knew that Nanshin-ron was not exactly a cakewalk through Southeast Asia. As Historian Owen Matthews writes, their main opposition was externally based:
“Their [the Imperial Navy’s] two main obstacles were the British Royal Navy, operating a force far more powerful from Japan’s from the apparently impregnable base of Singapore, and the US Pacific Fleet out of Pearl Harbor, Hawaii.”
The debate then, rested on which threat to combat first, and when to best strike. For those decisions, the military planners in Tokyo watched and waited as the Second World War in Europe developed.
A Chance to Strike?
With the Fall of France and the seemingly inevitable Nazi invasion of Britain, the Japanese government gained its own concessions in Southeast Asia, notably by securing the precious resources and territory of French Indochina (by essentially forcing Vichy France to agree to practical rule of the colony). When Japanese forces formally moved into the area, America responded with a potential death blow: an oil embargo. 90% of Japan’s oil supply came from foreign imports, and 75% of that supply came from the United States. Roosevelt had issued a clear warning through this freeze. Gordon on the Japanese options:
“It [the Japanese government] faced a difficult choice. It could agree to American conditions for lifting the embargo by retreating completely from China. Or it could follow the hawks and track the United States and British, taking control of the Southeast Asian oil fields by force and hopping to negotiate for a cease-fire from that strengthened position.”
The military was also aware of just how lethal this embargo was. Here’s an extract from a report pursuing the case for war following the embargo:
“oil is the weak point of our Empire’s national strength and fighting power… We are now gradually consuming oil that has been stockpiled…We will be self-sufficient for two years at most. This will be less if we carry out larger-scale military operations… our Empire will become powerless militarily.”
Then on June 22nd, a fateful cable from Ambassador Oshima (stationed in Berlin) arrived at Imperial headquarters: the Third Reich had launched Operation Barbarossa, and now the Soviets were in a full-blown war against Hitler's regime. To the Japanese planners, this now added a new dimension and avenue for expansion. Should the Japanese honour their alliance with Germany and attack the Soviet Far East? Or should they bide their time and wait for further developments? Minister of Foreign Affairs Yosuke Matsuoka certainly thought the former was the best option (despite having signed a non-aggression pact with the Soviets two months earlier).15 So strong was his belief that Japan should attack north first, then south, that he personally requested an audience with Emperor Hirohito, and the decision makers in Tokyo met a few days later to review his proposal.