Nhạ served with the Viet Minh during French-Indochina War, and transferred to South after the Geneva Accord in 1954.[1] In Vũng Tàu, Nhạ met Hoàng Quyền, an anti-communist priest who recommended him to the Ngo brothers.[1] He served on the presidential staff from 1957 until 1969.[1] In 1968, Nha warned the communists that the U.S. planned to curtail the annual Tết ceasefire.[2] During the Tet offensive he opened presidential wine cellar so that the palace guards would become drunk.[3] Assuming that the wine was distributed to improve morale, Thieu commended Nha when he returned to the palace a few days later.[3] In 1969, a probe by the U.S. Central Intelligence Agency exposed Nha as a spy. He was handed over to North Vietnam in 1973 as part of a prisoner exchange. His story received little attention at the time and is known mainly from the book Ông cố vấn (The Advisor) by Hữu Mai, which was published in 1989.