Ellis Island
During and immediately following World War II, Ellis Island was used to hold German merchant mariners and "enemy aliens"—Axis nationals detained for fear of spying, sabotage, and other fifth column activity. In December 1941, Ellis Island held 279 Japanese, 248 Germans, and 81 Italians removed from the East Coast. Unlike other wartime immigration detention stations, Ellis Island was designated as a permanent holding facility and was used to hold foreign nationals throughout the war. A total of 7,000 Germans, Italians and Japanese would be ultimately detained at Ellis Island. It was also a processing center for returning sick or wounded U.S. soldiers, and a Coast Guard training base. Ellis Island still managed to process tens of thousands of immigrants per year during this time, but many fewer than the hundreds of thousands per year who arrived before the war. After the war, immigration rapidly returned to earlier levels.
Clandestine HUMINT and covert action
In the years immediately preceding the Second World War, the U.S. had no standing clandestine HUMINT or covert action organizations. There were certainly examples of both, such as Marine Major Earl Ellis' series of visits, in the 1920s, to Japanese islands in the Pacific. Ellis, who died under mysterious circumstances while on duty, created the basic plan for U.S. "island hopping" operations in the Pacific Theater of the Second World War.