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, Calif. They were 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 ’60s were a time of autocratic and nepotistic rule by South Vietnam’s American-supported president, Ngo Dinh Diem, who in a largely Buddhist land favored Catholics in many walks of life. His refusal to allow elections in 1956 was a factor leading 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 had expected to be a nonviolent coup, other Vietnamese military plotters arranged to have President Diem deposed and shot dead in an armored personnel carrier en route to the airport and an anticipated exile abroad.
In the intrigue after the assassination, short-lived juntas were ended by coups. General Khiem was briefly part of a ruling junta before being sent into political exile as ambassador to the United States in 1964. From Washington, he conspired with Saigon generals to seize power. But on the day of a planned coup, he forgot to set his alarm clock and overslept. The coup went ahead 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 named premier, and he held that powerful post until the regime’s final days.
General Khiem lived in quiet retirement in San Jose, along with a number of other former high-ranking South Vietnamese officers. (He was finally baptized a Catholic there in 2018.)
The Vietnamese diaspora in the United States is highly factionalized, with former officers taking the hardest anti-Communist line. General Khiem avoided controversy by keeping a low profile and gave almost no interviews.
Seth Mydans contributed reporting.