The perceived racism of the West against Japan is not really the main reason that led to the outbreak of war in the Asia Pacific. However, it is one of the driving factor that led to war. Some Japanese believed that their invasion of China was a way of protecting them from Western interventions. The Japanese were convinced that the Western powers did not treat Asians as their equals. At the League of Nations, the Western powers refused to allow a statement in the covenant indicating that all races are equal. Furthermore, at the Washington Conference, the Japanese had been forced to reduce the size of her navy and to return Shandong to China. She was also unhappy that the Western powers did not agree with the equality of all races.
Another eeason that led to the outbreak of war is economic issues. As the Japanese population increased in the 1920s, she faced shortage of food as most of the country was mountainous. She did not have enough farmland to produce food that she needed and did not have raw materials such as coal and iron in her country. Hence, to import these resources, Japan needed to have the necessary funds, which she managed to obtain from her exports of silk and other products. However, the import of raw materials made Japan vulnerable as she would not be able to survive on her own. It also meant that is foreign countries did not buy her exports, she would not have the money to ensure the survival of her country. This was the case in 1929 when the Great Depression occured. America was the biggest importer of Japanese silk and with the fall in demand, many factories clased down and peasants were reduced to poverty.
Above all, I think the main reason that led to the outbreak of war is militarsm in Japan. Strong nationalistis feelings rose in Japan once fighting began in China. Any political leader who went against the invasion of China were assasinated. There were many assasination plots against those Japanese politicians who were weak in dealing with Western powers. Army and navy officers dominated the Cabinet were only answerable to Emperor Hirohito who in turn had to led with whatever decisions made link to war. With military in power, Japan had to invade and control places that were rich in resources and land so that she would be able to use them as she pleased.
The Japanese need for economic security and race inequality itself is not the main reason that led to war. It is the combination of this need and the rising nationalistic feelings and militarism in Japan that led her ambition to expand her economic empire beyong shores. Thus, militarism is the most important reason that led to war but without the other two factors, Japan would not have gone to war in the first place, which makes them important too.