Working Paper（24-016E）Japan’s economic warfare in the 1930s and early 1940s

Japan’s participation in World War II was a consequence of self-reinforcing cycles of Japan’s aggressions in East Asia and the economic sanctions imposed on Japan by the Western countries. During the war, the United States blocked transportation of natural resources to Japan from the Great East Asia Co-Prosperity Sphere using its naval power, particularly submarine attacks on Japanese ships. Japan managed to adapt to this blockade strategy of the United States by adopting various measures, including accelerating merchant ship building to maintain the marine shipping capacity and substituting domestic resources for imported raw materials. Although limits were ultimately reached, these measures for adaptation enabled Japan to continue the war for more than three and a half years.

Key words: Economic sanction, blockade, international politics, adaptation, autarchy, sea lane battle, shipbuilding, import substitution, national nutrition, gun-butter trade off, Japan