Why did Japan attack Pearl Harbor?

Just before 8:00 am on Sunday, December 7, 1941, the first Japanese dive-bomber appeared over Pearl Harbour, Hawaii. And for the next hour, the Japanese strike force of 353 aircraft would launch a merciless assault with guns, bombs, and torpedoes that would destroy more than 180 US aircraft, damage or destroy more than a dozen ships, and claim the lives of more than 2,400 military personnel and civilians on the island – making this attack the most successful surprise attack in the early years of aerial/naval combat!

But why did Japan take such a drastic action that would eventually become their undoing as it dragged the United States into World War II, culminating in the atomic bombing of Hiroshima and Nagasaki?

The short answer to this answer is ‘oil.’ 

Japan began modernizing its economy at the turn of the 20th century to transform the country into a world super empire. However, Japan lacked the natural resources to drive that transformation. Consequently, they had to import about 94% of the oil supply. But in 1937, Japan got bogged down in a full-scale war with China, and after capturing Manchuria, Japan needed even more oil resources. Read on for a longer explanation. 

But the final blow came in 1942 when Japan occupied French Indochina. Consequently, the U.S. retaliated by imposing strict sanctions on Japan, freezing all its assets in the states, and preventing them from purchasing oil. Unwilling to submit to U.S. requests, Japan’s only choice was to take the oil they needed by force. 

Their initial strategy was simple: try to occupy the Dutch East Indies and Malaya territories so they could access critical residing resources like oil and rubber. However, the Japanese knew that doing so would provoke an armed U.S. response that could devastate their cause. Hence, they decided to weaken the United States’ position by attacking the U.S. Pacific fleet at Pearl Harbour, forcing the United States to negotiate peace. 

But before moving in on Pearl Harbour, the Japanese sought to resolve the economic strangulation from the United States through diplomatic means. However, after several failed attempts, on December 1, 1941, Hideki Tojo, the general of the Imperial Japanese Army (IJA), declared in a meeting with the emperor and his privy council, “It is now clear that Japan’s claims cannot be attained through diplomatic means.” Although reluctant, the emperor, Hirohito, asked for a vote, and the cabinet unanimously voted to attack Pearl Harbour. After this, the Japanese fleet was instructed to attack Pearl Harbour six days later unless there was a sudden change in the United States’ attitude. Unfortunately, that never happened, and the attack proceeded as planned. 

However, things didn’t go as the Japanese had anticipated after the attack. Instead of remaining isolated and agreeing to peace terms, the U.S. geared up for total war after Roosevelt’s famous ‘Day of Infamy speech.’ For the next four years, the U.S. would be an instrumental player in the Allied Forces, prevailing in the battle of the Pacific and eventually defeating Imperialist Japan through the use of the world’s first nuclear weapons, thereby accelerating the conclusion of the infamous Second World War.