Japan's Plans After Pearl Harbor

It was a question that many pondered after Japan left the United States naval base at Pearl Harbor in ruins. "Why did this happen?" And with more than 2,400 American lives taken during the attack, the nation collectively needed an answer. The answer turned out to be that Japan, fearing the United States would get in the way of its expansion across Southeast Asia and throughout the Pacific, had hoped to disable the US Pacific Fleet.

Aerial view of Pearl Harbor, December 7, 1941

But what was Japan’s plan for after the attack was successfully carried out? What did it hope to accomplish with the Americans out of the picture? For that answer, we look to actions immediately following the Dec. 7, 1941 attack on Pearl Harbor. The United States apparently wasn’t the target beyond the fleet in Oahu, since the Imperial Japanese Navy never encroached on the US West Coast. Instead, Japan had its sights set on territories around the South China Sea and the Philippines.

After Pearl Harbor

It didn’t take long after the attack on Pearl Harbor for Japan to shift its attention to the Philippines. Nine hours after the attack, the Japanese launched an invasion of the Philippines. As if Pearl Harbor hadn’t been a severe enough blow to the United States, its attempt at defending the Philippines cost more than 23,000 American killed or captured, and an additional 100,000 Filipino casualties. And the Philippines wasn’t all Japan intended to conquer once the United States out of the way.

Japanese forces land on Java

On Dec. 17, 1941, just ten days after its aerial strike force devastated the naval base at Pearl Harbor, Japan landed forces at Miri, an oil production city on Malaysian Borneo. Nine days earlier, Japanese troops had started to land at other points along the north coast of the island of Borneo including Seria, Jesselton, Kuching, and Sandakan, an effort that lasted until January 31, 1942. These invasions were the first steps in the takeover of the resource-rich Dutch East Indies.

A Plan Doomed from the Start

As it turns out, however, control of the Dutch East Indies wasn’t enough, especially after the United States—having quickly recovered from an attack that was intended to completely disable their fleet—joined the war in the Pacific. Though the Allies fought bitterly to retake many islands throughout the Pacific Theater, they never attempted to retake Java, Sumatra, Bali, or Timor. These islands were turned over when Japan was forced to surrender in 1945.

The greatest flaw in Japan’s ultimate plan was assuming the attack on Pearl Harbor would succeed as intended. Though the US Pacific Fleet did suffer extensive damage, it was far from being destroyed as the attackers had hoped it would be.