The Wrong Side of Honor by Marshall Ginevan

1974. The Vietnam War is over for the US military. Air force fighter pilot Eddie Donevant is reassigned to an intelligence office while military units back out of Thailand. CIA officers, fired for smuggling opium. Return as independent businessmen, paying warlords and communist military units to move drug loads. Lt. Donevant battles the drug trade while advance into South Vietnam and Cambodia. Defying orders, he wages a war this enemy no one will acknowledge exists and brings his military career and his military career and hid life to the brink.