United States home front during World War I

I-25在射程外，所以沒有回擊。之後有美軍飛機在訓練中發現了潛艇，隨後派出攻擊機追擊，但I-25逃脫了。 第一次世界大戰美洲戰區（英语：United States home front during World War I#Attacks on the USA）

（页面存档备份，存于互联网档案馆）. Emily Yellin, Our Mothers' War: American Women at Home and at the Front During World War II, Free Press, 2004, ISBN 0-7432-4514-8 p.

the end of World War II, "The United States Government has estimated that German forces and other Nazi agents before and during World War II had seized

from 1800 to 1935. Addis Ababa: Haile Selassie I University. 1968. OCLC 434191.  Peace and War: United States Foreign Policy 1931–1941 online. Washington

Norwegian Campaign United States Department of State Foreign relations of the United States diplomatic papers, 1940. General Volume I （页面存档备份，存于互联网档案馆） p. 136