By the beginning of 1954, Dien Bien Phu alone required 20 C-119s and 50 C-47s, so, on January 2, Navarre's second-in-command asked for additional aircraft and crews under the so-called "Navarre Plan." U.S. President Eisenhower, fearing both domestic and international backlashes if he were to send in U.S. troops, sent an American mission to Indochina to determine the extent of help that the French needed. Following a personal letter from the French prime minister, Joseph Laniel, Eisenhower authorized the loan of aircraft with French markings painted on them and flown by crews from Civil Air Transport (CAT), a commercial airline, which had been started in 1946 by then-retired Major General Chennault, the famous commander of the American Volunteer Group (AVG), better known as the "Flying Tigers", in China during World War II, and then purchased by the CIA in the year war broke out in Korea. He further authorized the dispatch of American "specialists" to Indochina, that is, mechanics from the Far East Air Force (FEAF) of the USAF. Once sworn to secrecy owing to the political ramifications of their presence, they would go to work on B-26s at Da Nang (then called Tourane) in the south and on C-47s at Do Son, located south of Haiphong, in the north, respectively. (In fact, Eisenhower was so concerned about their presence, which itself caused the Chinese government to label the American mechanics as "combatants", that he told U.S. Secretary of State John Foster Dulles that he wanted them withdrawn by the end of June 1954 no matter what the situation in Indochina was at that time.)