He originally served in the Vietnamese National Army under General Nguyễn Văn Hinh.

[2][3] Vy returned to South Vietnam after the 1963 coup which removed Diem from power and led to his assassination.

It was the late President Diem and his brother Ngo Dinh Nhu who want to open talks with the North Vietnamese.

He rose to the rank of Lieutenant General, and was appointed Chief of Staff of the Army of the Republic of Vietnam in 1967.

[7] On 22 March Thiệu dismissed five of Vy's senior aides due to a scandal relating to the SMASF.