In 1943, Moose became the second accredited U.S. representative to Saudi Arabia (following Bert Fish) as chargé d'affaires, but the first to officially reside in Jeddah, where he opened the American legation on May 1, 1943.[4] He served until mid-1944 although he remained involved in Saudi-American relations until later in 1945 including helping arrange the meeting between the King of Saudi Arabia, Abdul-Aziz Ibn Saud, and President Franklin D. Roosevelt in the Gulf of Suez in 1945.