Here There are Tigers: The Secret Air War in Laos and North Vietnam, 1968-69 by Reginald Hathorn
At the chaotic height of the Vietnam War in 1968 and 1969, Maj. Reginald Hathorn flew 229 combat missions as a forward air controller for the U.S. Air Force under the call sign of Nail 31. During both day and night, he piloted his Cessna O-2 into Laos, where he inserted Special Forces teams, conducted missions with the CIA, helped rescue downed pilots, and called in air strikes against enemy targets on the Ho Chi Minh Trail--in a war which did not officially exist.