In 1978, only two years after North Vietnamese forces finally took Saigon and united Vietnam under the Communist rule, Tảng became disillusioned with the government of the Socialist Republic of Vietnam, which he believed did not give equal standing to southern sympathizers. Not helping matters was the imprisonment of two of his brothers in North Vietnamese reeducation camps. While it was supposed to last only thirty days, the imprisonment of his younger brother, Bich, a director at the National Bank, was prolonged, and he was released only after many months of lobbying on the part of Tảng.
Tảng's disillusionment with the government occurred shortly after Vietnam was unified under communist rule, following the fall of Saigon. He believed that the Socialist Republic of Vietnam did not treat southern sympathizers equally. The imprisonment of his brothers in North Vietnamese camps further strained his relationship with the government.