On Sept. 1, 1939, the world watched in horror as Nazi troops, led by Adolf Hitler, invaded Poland. With Austria and Czechoslovakia having already fallen under German control, Britain, France, Australia, New Zealand, India and Canada within days declared war on Germany, starting World War II.

The United States began to wage economic warfare on Japan, imposing stringent economic sanctions.

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Rooted in an isolationist stance, the United States remained neutral. President Franklin D. Roosevelt knew Americans would not support another European conflict, having suffered numerous casualties during World War I, so he resisted a rush to war. Still, despite the United States’ official proclamation of neutrality on Sept. 5, 1940, FDR began preparing for military involvement by declaring a state of national emergency, increasing the size of the Army and National Guard, and authorizing the Selective Training and Service Act of 1940 — the first peacetime draft in US history.

On Sept. 27, 1940, Japan, Germany and Italy agreed to the Tripartite Pact, pledging mutual support if attacked by a nation not already at war. The alliance sent a direct warning to the United States that any military intervention would lead to battles both in Europe and the Pacific.

Empowered by the pact, Axis countries continued their assaults in the Pacific and Europe. Japan invaded Manchuria in 1931 and China in 1937, and the Nazi defeat of France in 1940 and possible collapse of Britain to Axis forces prompted Congress to repeal provisions of the Neutrality Act. This authorized the President to sell, transfer or lease war goods to the government of any country whose defenses he deemed vital to the defense of the United States.

US wages economic warfare

Although Roosevelt initially avoided military conflict, the United States began to wage economic warfare on Japan, imposing stringent economic sanctions. This included closing the Panama Canal to Japanese ships in 1940, and embargoing scrap iron and steel exports to all destinations other than Great Britain and Western nations. 

The British and the Dutch also embargoed exports to Japan from their Southeast Asian colonies, putting the Japanese in an economic stranglehold. This only fueled Japanese aggression, leading to Japan’s September 1940 invasion of French Indochina (now Vietnam).

On July 26, 1941, Roosevelt froze Japanese assets in the United States, and followed up a month later with an oil embargo on Japan, essentially ending commercial relations between the two countries.

MIS Language School opens

As World War II intensified in the Pacific, the United States was in dire need of Japanese linguists and secretly recruited Nisei soldiers in 1941 to enroll in its Military Intelligence Service Language School (MISLS), first at the Presidio Army post in San Francisco, then later at Camp Savage and Fort Snelling in Minnesota.

Over the course of World War II, the MISLS recruited hundreds of students from mainland internment camps and from Hawaii. Some 200 members of the 100th Infantry Battalion training at Fort McCoy, Wisconsin, were transferred to the MISLS in December 1942, and in 1943, MIS students were also reassigned from the 442nd Regimental Combat Team training at Camp Shelby, Mississippi.

Although officials were initially reluctant to trust Japanese-Americans with military intelligence, these Nisei linguists would provide invaluable service during the war.