Why did Japan attack Pearl Harbor?

On the fateful morning of December 7, 1941, the peace of Pearl Harbor was shattered by the sudden roar of bombs as the Japanese Navy’s combined fleet arrived for a surprise attack. This marked the beginning of the Pacific War, a conflict that would ultimately lead to Japan’s downfall with the entry of the United States.

We need to rewind a bit to understand why Japan resorted to this desperate attack. In the eight months leading up to the outbreak of the Pacific War, the United States and Japan engaged in diplomatic negotiations that directly influenced Japan’s decision to launch a sneak attack.

Why did Japan attack Pearl Harbor?

In 1937, Japan had already launched a full-scale aggression against China. It’s important to note that Japan heavily relied on the United States for support and resources during this time, with as much as 80% of its oil coming from the U.S. This dependency prompted Japan to search for alternative oil sources in Northeast China.

Beyond oil, Japan relied on the U.S. for other essential resources and military supplies. The United States was a major exporter of materials to Japan, including critical items like oil, steel, and raw cotton, which were vital for Japan’s military expansion.

However, Japan’s aggressive actions in China began to draw the ire of the American public, leading the U.S. government to advise major companies against trading with Japan. While there was no legal backing for this, the export of goods, including aircraft and parts, increased significantly, signaling growing American dissatisfaction with Japan’s behavior.

By 1939, as the Japanese military occupied Hainan Island and the Paracel Islands, posing a threat to U.S. interests in Southeast Asia, the United States initiated an embargo on Japanese aircraft and aviation parts. They also canceled the 1911 “Japan-U.S. Commerce and Navigation Treaty” and placed strategic materials like aluminum, tungsten, and nickel on the embargo list in 1940.

In this context, the United States contemplated entering the war but faced internal opposition and challenges in Europe, particularly with Britain. The United States adopted a “Europe first, Asia later” strategy to avoid simultaneous conflicts with Germany and Japan and reduce casualties. In preparation, the U.S. Pacific Fleet was stationed at Pearl Harbor in the spring of 1940.

Despite Japan’s earlier denials of intentions to occupy southern Indochina, the United States received intelligence indicating otherwise. This led the U.S. to realize that appeasement couldn’t restrain Japan’s expansionist ambitions.

As tensions escalated, the United States imposed various embargo measures to restrict Japan’s actions. On August 30, 1940, the U.S. froze all Japanese assets but continued supplying oil to prevent Japanese aggression in the Dutch East Indies and to keep South Pacific supply lines open.

Nonetheless, these measures didn’t deter Japan from moving southward. As resource shortages intensified and the Chinese war prolonged, Japan was in dire straits. Despite negotiations with the United States, Japan had already formulated plans to attack Pearl Harbor if diplomacy failed.

On November 6, 1941, Japan proposed a compromise to the United States, which was rejected. Subsequently, they revised the proposal, and although the U.S. showed some recognition, they insisted on Japan halting its southward expansion and lifting economic sanctions. This condition revealed the U.S. preference to avoid war but stop Japan’s aggression.

Following these negotiations, Japan received the “Hull Memorandum” from the U.S., demanding an unconditional withdrawal from China and Indo-China, the dissolution of the Triple Alliance Treaty with Germany and Italy, and the signing of a non-aggression treaty. This ultimatum pushed Japan to make the fateful decision to attack the United States.

On December 6, 1941, Japan’s naval combined fleet set sail for Pearl Harbor to deal a devastating blow to the U.S. Pacific Fleet. The fleet included six aircraft carriers and numerous ships.

In the early hours of December 7, 1941, as thick fog shrouded Pearl Harbor, the U.S. Navy was caught off guard and unprepared for an attack. Japanese warplanes suddenly descended from the skies, launching a deadly assault. Hundreds of aircraft wreaked havoc within minutes, destroying American warships, aircraft, and facilities. Explosions and flames painted a horrifying scene over Pearl Harbor, leaving the U.S. fleet severely crippled.

This surprise attack claimed the lives of 2,403 American soldiers, injured 1,178 others, and inflicted extensive damage on the U.S. Pacific Fleet. Pearl Harbor was left in ruins, forever altering the course of history.

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In response, the United States declared war on Japan, officially marking the start of the Pacific War and cementing the attack on Pearl Harbor as a defining moment in American history. However, to truly grasp the reasons behind this attack, we must delve into the diplomatic negotiations that led Japan to take military action. These negotiations reached an impasse, with the U.S. imposing harsh conditions that Japan found unbearable, ultimately driving them to launch the attack on Pearl Harbor to secure their interests.