During the 1950s, Tung was a high-ranking official in Nhu's Cần Lao, a secret political apparatus which maintained the Ngô family's grip on power, extorting money from wealthy businessmen. In 1960, Tung was promoted directly to the rank of colonel and became the commander of the special forces. His period at the helm of South Vietnam's elite troops was noted mostly for his work in repressing dissidents, rather than fighting the Viet Cong insurgents. His best-known attack was the raid on Xá Lợi pagoda on 21 August 1963, in which hundreds died or disappeared.