After the Japanese attack on Pearl Harbor on December 7 , 1941 , followed by Nazi Germany 's declaration of war on the United States four days later ( and the United States ' declaration of war on Germany in response ) , Hitler authorized a mission to sabotage the American war effort and attack civilian targets to demoralize the American civilian population inside the United States . The mission was headed by Admiral Wilhelm Canaris , chief of the German '' Abwehr '' . Canaris recalled that during World War I , he organized the sabotage of French installations in Morocco , and entered the United States with other German agents to plant bombs in New York arms factories , including the destruction of munitions supplies at Black Tom Island , in 1916 . He hoped that Operation Pastorius would have the same kind of success they had in 1916
destruction of munitions supplies at Black Tom Island
Black Tom explosion
Operation Pastorius