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 became disheartened with the government of Vietnam just two years after it came under communist control, feeling that it did not treat southern sympathizers fairly. His dissatisfaction was worsened by the imprisonment of his brothers in North Vietnamese camps, and the lengthy detention of his younger brother Bich, who was eventually released only after Tảng's persistent advocacy.