Wondering Out Loud: Why did Japan attack Pearl Harbor?

Author: Ed Cohen

Japan became a rising world power with its victory in the 1905 Russo-Japanese War, but the country felt increasingly at a disadvantage economically and politically as European powers and the United States raced into China and other parts of Asia to establish colonies and trade relationships. Japanese society turned more and more militaristic and nationalistic, culminating in an invasion of Manchuria in 1931 and brutal incursions into other parts of China in 1937.

Franklin Roosevelt’s administration responded in 1940 by placing a scrap metal embargo against Japan followed by a supposed limited oil embargo a year later. Strong evidence suggests that Assistant Secretary of State Dean Acheson single-handedly implemented a de facto total oil embargo while President Roosevelt was out of the country. And by the time Roosevelt found out, it was too late to reverse the action without losing credibility.

Japan could have escaped the embargoes simply by pulling out of China. But the country’s military leaders viewed acquiescence as dishonorable and believed it would weaken the credibility of the Empire and cause domestic political upheaval. A potential replacement source of oil could have been had through conquest of the Dutch East Indies, but the Japanese calculated that aggression against the East Indies would spark war with the United States.

Japan knew it couldn’t possibly conquer the United States, but its leaders gambled that a surprise attack on Pearl Harbor would leave Roosevelt in a weakened negotiating position on the embargoes. The thinking was that a demoralized and isolationist American public would prefer negotiation to prolonged war.

They were wrong.
Sources: Daniel Lindley, assistant professor, political science, Adam Shanko ’04 and Jennifer Wiemer ’03_