Project 404

Project 404 was the code name for a covert United States Air Force advisory mission to Laos during the later years of the Second Indochina War, which would eventually become known in the United States as the Vietnam War. The purpose of the mission was to supply the line crew technicians needed to support and train the Royal Laotian Air Force, while Raven Forward Air Controllers were brought in to supply piloting expertise and guidance for running a tactical air force. The two programs together comprised Palace Dog.
Project 404 began in 1966, as a successor after the completion of Operation White Star, was smaller in scope, and was an adjunct to the various covert ground operations succeeding White Star. Because Laos was ostensibly a neutral party to the conflict between the United States and North Vietnam, the airmen did not wear United States Air Force uniforms, but instead worked in civilian clothing.