What Caused Japanese Aggression in World War II?

Nationalist Beliefs

Some intellectuals, and military leaders especially, formed the belief that the Japanese people were racially and ethnically superior to other people and races

Many nationalists believed that the Japanese were descendants of the Shinto gods. Propaganda promoted the belief that the Japanese emperors were direct descendants of the Sun Goddess, Amaterasu. 

As a result, Japan believed that it was their destiny to rule Asia, and maybe even the world.

The Sino-Japanese War and the response of Western powers

During the Sino-Japanese war, Japan faced a lack of many materials which were important in the event of War, including oil, rubber, iron, etc

Furthermore, although Japan had been able to conquer coastal China with relative ease, the interior was unexpectedly difficult to conquer. This is due to the fact that the Nationalist and Communist armies of China were able to effectively defend the large Chinese interior. 

Furthermore, Japanese aggression towards China had resulted in sanctions and trade embargoes from Western Countries, which were beginning to fear Japan encroaching on their colonies and spheres of influence.

This was dangerous for Japan, as their mainland lacked natural, mineral resources, and they relied on other powers for the trade of raw materials.

Japanese Expansion (The Southern Expansion)

After allying with Germany, Japan began to seize territories that were colonised by their enemies, the British, the French and the Dutch.

Japan simultaneously attacked the Philippines, Hong Kong, Singapore, and Malaya, in a lightning-fast "Southern Expansion".

To sustain the level of resources needed for conflict in China, Japan began to annex territories for supplies.

The US stance towards Japan

From 1938, the USA had begun a more aggressive policy towards Japan.

In 1938, Roosevelt used his presidential powers to ignore the Neutrality Acts, which treated aggressors and victims equally, and gave more active support to the Nationalists in China. This support included an oil loan of $25 million at first.

By doing so, Roosevelt showed that he did not share the same sentiments of the isolationists.

Sanctions placed on Japan:

 US aid to China:

The Bombing of Pearl Harbour

Roosevelt was trying to push an interference policy in terms of the Sino-Japanese War, as he wished to be more involved in international affairs. 

This sentiment was not widely shared until the Bombing of Pearl Harbour.

On 7th December 1941, with the aim of mitigating the US response to the annexation of Asian territories, Japan decided to decimate the U.S. Pacific Fleet at Pearl Harbor.

Roosevelt requested a vote on the declaration of War, which was accepted by Congress.

Roosevelt declared War after winning the vote, with only one member of Congress voting against War.

Japan had not been considered as a threat initially as they had made efforts to maintain a friendly relationship, such as...

Shown on the images on the left are the extent of Japanese conquests during the Second World War.