Guarding the United States meant guarding the entire Western Hemisphere from Nazi encroachment. In other words, it wasn’t enough to fortify U.S. defenses. South America must be protected as well. Roosevelt talked about hemisphere defense in speeches, arguing that “no attack is so unlikely or impossible that it may be ignored,” and Secretary of the Navy Frank Knox raised the specter of Nazi planes taking off from South American airfields in the night and dropping bombs on “our own women and children in our teeming seaboard cities.”
