Diệm was killed in a November 1963 coup, allowing Thi to return to South Vietnam and resume his military service. Soon after arriving home, Thi found himself involved in another coup plot, acting as the link between Khánh and Đỗ Mậu, two generals disgruntled with their position under the military junta of Minh, who oversaw the overthrow of Diệm. Mau was one of the principal tacticians in the 1963 coup; although he did not command troops, he had a thorough knowledge of the backgrounds of the ARVN officers and their strengths, weaknesses and characteristics through his role as Diệm's director of military security, and this understanding had allowed him to engineer the previous coup. Minh's junta feared Mau's shrewdness and tried to sideline him by making him the Minister of Information, a relatively unimportant position.