He married Yen Dinh in 1950 and they had a daughter. His first wife died in 2004 and in 2005 he married Ann Chastain, of Eureka, California. They divorced in 2012. He is survived by his daughter, Yen Khanh, and an adopted son, Tran Khan, as well as a granddaughter.
The late 1950s and early 1960s were a time of autocratic and nepotistic rule by the US-backed President of South Vietnam, Ngo Dinh Diem, who, in a largely Buddhist country, favored Catholics in many many areas. His refusal to allow elections in 1956 was a factor that led to the Vietnam War. In 1960, Colonel Khiem crushed a coup against Mr. Diem, his godfather, and was promoted to general.
But in 1963, in what the Kennedy administration and General Khiem expected to be a non-violent coup, other Vietnamese military plotters arranged for President Diem to be deposed and shot in an armored vehicle. transport of troops en route to the airport and a planned exile abroad.
In the post-assassination plot, ephemeral juntas were ended by coups. General Khiem briefly served in a ruling junta before being sent into political exile as Ambassador to the United States in 1964. From Washington, he conspired with the generals in Saigon to seize power . But on the day of a planned coup, he forgot to set his alarm clock and slept too long. The coup took place without him and failed.
In 1965, another junta, which included General Thieu and General Ky, appointed Mr. Khiem ambassador to Taiwan. He was brought back to Saigon in 1968 and pledged loyalty to the newly elected President Thieu. A year later he was appointed Prime Minister and he held this powerful post until the last days of the regime.
General Khiem lived in a quiet retreat in San José, with a number of former high-ranking South Vietnamese officers. (He was finally baptized Catholic there in 2018.)
The Vietnamese diaspora in the United States is heavily fractured, with former officers taking the harshest anti-Communist line. General Khiem avoided controversy by keeping a low profile and gave almost no interviews.
Seth Mydans contributed reporting.