According to Wikipedia (https://en.wikipedia.org/wiki/Civil_Air_Transport) Civil Air Transport (CAT) was originally a Nationalist Chinese airline, later owned by the U.S. Central Intelligence Agency (CIA), that supported United States covert operations throughout East and Southeast Asia. CAT was created by General Claire L. Chennault and Whiting Willauer in 1946 as Chinese National Relief and Rehabilitation Administration (CNRRA) Air Transport. 

On May 1, 1953, 'Operation Squaw' began, calling for CAT to airdrop supplies to French troops besieged at Na Sam, Laos. This operation was the first U.S. involvement in what became the First Indochina War. 

'Operation Squaw-II' was approved on January 29, 1954, and, after negotiations with the French, a contract was signed on March 3 for CAT to supply 24 pilots to operate 12 C-119 transport aircraft in support of French troops. 

At the Battle of Dien Bien Phu, CAT supplied the French garrison by parachuting troops and supplies with covert USAF C-119 inscribed with French Air Force insignia. 

Two CAT pilots James B. McGovern Jr. and Wallace Buford were killed in action during the siege of Dien Bien Phu in May 1954. They were the first American casualties of what was later termed 'The Vietnam War'. McGovern's remains were recovered in 2002 and identified in 2006. 

Wallace Buford's remains have never been found.

Links to Major Documents in the crash of CAT C-119 on 6 May 1954: 

Buford's Last Flight
Maj Gen Chennault (USAF Ret.) letter
Kansas City Kansan: Newspaper Report
Wallace Buford Medals
Unclassified Investigative Report