Why Did Japan Attack So Many Southeast Asian Countries in World War II?

by Quin Cho

Japan’s “Meiji Restoration”—which spelled the end of the country’s isolation from the West during the reign of the Tokugawa Shoguns--allowed it to embark upon a campaign of modernization and westernization. Within the scope of a few decades, Japan modernized and became the most powerful country in East Asia, with that result cemented in blood by the First Sino-Japanese War and the Russo-Japanese War. Thereafter, Japan decided to emulate the Western Powers that colonized or subdued most of the non-Western world in the nineteenth and early twentieth centuries; in other words, Japan became an imperial power in East Asia. It annexed Formosa (Taiwan) in 1895, Korea in 1910, and the Caroline and Mariana Islands after World War I. 

(continued) Field officers (Colonels Kanji Ishiwara and Seishiro Itagaki) in the Kwantung Army—a hotbed of right wing ultra-nationalism—then capitalized on China’s period of semi-colonial, semi-feudal weakness to seize Manchuria, in the hopes that this would provide Japan with coal, iron ore, grain, and surplus land (Pike, 142 and Beevor, 7). Unfortunately for the Japanese, the seizure of Manchuria did not resolve any of Japan’s many economic and social problems in the midst of the Great Depression. Right-wing ultra-nationalism became popular in the officer corps, and a strange concoction of right-wing assassinations, attempted coups, and political fecklessness led to the demise of Japanese parliamentary democracy. Partially as a result of the increasing influence of the militarists, the Japanese Imperial General Staff decided to invade China, in the hopes that the country could be defeated swiftly and therefore be a reserve of foodstuffs and raw materials. ​

Despite initial Japanese operational success in China, the Japanese failed to deliver a decisive blow to the Chinese forces in the field and defeat China in 6 months. By 1939, the Japanese advance had almost completely stalled due to poor logistics and newfound operational failures (notably at the 1st Battle of Changsha). Furthermore, Japan had limited remaining supplies of two vital raw materials—rubber and tin—to continue the war in China (rubber being necessary for vehicle tires, and tin being necessary for cans to prevent rations from spoiling, among other things). This reality—combined with defeat at the hands of the Soviets during the Battle of Khalkhin Gol and the destruction of the 23rd Infantry Division—led to the “Strike South” faction (Nanshin-ron) that wanted to attack Southeast Asia winning out against the “Strike North” faction (Hokushin-ron) that wanted to attack the Soviet Union. Those advocating Nanshin-ron sought to capture the European and American Southeast Asian colonial possessions—namely the Dutch East Indies, Malaysia, Burma, French Indochina, the Philippines, and—and their reserves of raw materials. These included rubber, tin, cobalt, tungsten, oil, and foodstuffs, among other things. Therefore, after the fall of France in June 1940, the Japanese procured rights to naval and air bases in French Indochina from the newly founded Vichy French government. The acquisition of French Indochina would allow the Japanese to have a base of operations to strike the Dutch East Indies, Malaysia, Thailand. Additionally, Indochina also served as a massive reservoir of rice to be exported to Japan.
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The Americans felt that Japanese aggression against China and French Indochina was a direct threat to their economic interests in the region (namely the “Open Door Policy” with regards to China). Therefore, the US froze all Japanese assets in the US after the Japanese established bases in Indochina (which prevented them from buying vital materials such as copper and scrap iron), and then imposed an oil embargo. At this point, Japan was not only short of tin and rubber, but would soon rapidly have to face the reality of dwindling oil stockpiles. The American conditions for a removal of the embargo hinged upon a withdrawal of Japanese forces from China and Indochina. These proposals were rejected, however, as by this point the war in China had been glorified to the Japanese public and was a source of legitimacy to the right-wing militarists in charge of the country in 1941. The decision to continue the war in China therefore necessitated the seizure of the Netherlands East Indies, which had a variety of raw materials (most notably oil), British Malaya (with its tin and rubber), the Philippines (which were in the way and could serve as a US base to interdict Japanese operations in Malaya and the Dutch East Indies), and British controlled Burma, among other places. The Japanese Imperial General Staff opted to initiate near-simultaneous amphibious landings in Malaya, Thailand (on the Kra Isthmus) the Philippines, Hong Kong, Guam, Wake Island, and the various islands in the Dutch East Indies in December 1941 and January 1942 due to the position of the moon and tides (which influences when amphibious landings can take place). The necessity of destroying US Pacific Fleet at Pearl Harbor and its capacity to partake in the war in a surprise attack was also agreed upon. By September 1941, the die was cast: Nanshin-ron was the way forward, and the war in the Asia-Pacific was to expand into Southeast Asia.

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