駐日アメリカ合衆国大使
After university, Green became the secretary of United States Ambassador to Japan, Joseph Grew in Tokyo. Shortly before the Attack on Pearl Harbor, Green returned to the United States to study for the exam to join the United States Foreign Service. With the entry of the U.S. into World War II, Green enlisted in the United States Navy, where he served as a Japanese language translator (he had learned Japanese during his time in Tokyo).