General Vien was the Chief of JGS, yet he always avoided critical decisions. He did not question MACV for fear of creating conflicts. Vien also made very few suggestions to Thieu to avoid difficult decisions and suspicions from Thieu. He reasoned that the defense policies were set by the President (of course with borrowed ideas from the U.S.), the means and plans were already developed by MACV. The Army Corps, Divisions, Sectors Commanders were to execute the approved policies and plans without questioning.
When the 1963 coup was taking place, as the commander of the Airborne Brigade, Vien did show his poise and determination. This had gained him respect and admiration from many. After the readjust coup, Vien decided to keep a distance from the harmful political events. He frequently complained to friends, "I don't want to make enemies out of friends in a short time like that."
Knowing Thieu very personally from the old days, Vien did not condone Thieu's behavior in protecting his own personal interest. To Ky, Vien felt some closeness because of Ky's similar straightforward character and convictions. To Quang, Vien truly disliked his lack of loyalty to friends and colleagues. (When Ngo Dinh Can was put on trial, Quang served as juror, despite the fact that Can was Quang's own godfather.) Quang also had a despicable habit of back-stabling. Vien knew that Thieu wanted to assign Quang as Chief of the JGS of the ARVN since 1965, but did not do so because of strong resistance from the U.S. and the public. Knowing that Thieu would find a chance to remove him, Vien tried his best to persuade Thieu that no threat to Thieu's power was coming from the JGS.
Orders were cut for Vien to become Chief of the JGS instead of Quang because: the U.S. favored Vien; Thieu knew he could have his ways with Vien; Vien would not participate in any political coup.
No matter how irrelevant it might appear, there was another possible reason, superstition. Vien's astrological horoscope shows that he was "the force" capable to contain the power of Vo Nguyen Giap. Thieu frequently talked about that with a lot of interest. (This very well might have been the prep-work of the CIA or Vien's supporters themselves). Similar to most other high officials of his time, Vien frequently did everything suggested by MACV, without hesitation, to please the U.S. As a result, Vien had gained major trust and support from the U.S. The more U.S. troops entered Vietnam, the more stable Vien's position became.
From a distance and superficially, Vien appeared not to care about fame and promotion. Practicing Yoga on a daily basis Vien had submitted his request for resignation four times. However, Vien was very skillful in building trust from his boss and very successful in consolidating his position. For example, as the Commander in Chief, Thieu usually gave direct orders to the Army Corps commanders without even consulting Vien. Elderly Lieutenant General Nguyen Van La, his Deputy, felt uneasy about that breach in protocol asked him, "They treat the JGS as a decorative item, don't they?" Vien answered, "Let them do it, it's less work for us."
To strengthen his position, Vien let General Vy assume the post of Minister of Defense and nominated Major General Dong Van Khuyen to the Chief of Logistics and Chief of Staff at the JGS. Since the day Khuyen graduated from the Military Academy until becoming a Lieutenant General, he never even commanded a fighting platoon. Because of his loyalty, work attitude, and his ways of meeting the needs of supervisors, Khuyen was promoted quickly. During the First Republic, Khuyen was jailed for bringing Top Secret material home which were stolen by his communist brother. After 1963, this was put aside and forgotten.
After Khuyen was assigned to the new position, no officials, including those from the Ministry of Defense, ever interfered with the JGS anymore. The JGS now focused on Purchasing and Supplies activities and paid little attention to military operations. Sometimes when it was necessary to appear with the President in public events, Vien assigned his assistant to take his place. Thieu knew Vien's feeling very well but said nothing. Both Vien and Thieu must accommodate each other in order to survive. After being elected to Vice President, Tran Van Huong suggested to Thieu to promote Lieutenant General Do Cao Tri to a commanding position in Military Region 3. Thieu felt very uneasy to do so. He knew Tri was a true fighting general with many years of experience in the battlefields. Tri even had more seniority than Vien and Thieu. No one knew what was in Tri's mind. Huong also suggested to Thieu to replace Vien, but Huong had no understanding of the strange relation between Thieu and Vien as he did not understand the U.S.
When Huong was assigned Chairman of the Anti-Corruption Committee, assisted by Brigadier General Nguyen Van Hieu, Thieu agreed with Huong to review Vien's files. Huong told me in a private family dinner in Vinh Long that he had suggested to Thieu to review Vien's files, and also Quang's files, in the near future. I explained to Huong that even if Vien was demoted, he would have been replaced by Quang, but not by Tri. Furthermore, it was very difficult for Thieu and Huong to dismiss Vien. Since there was not enough evidence of Vien's lack of performance and loyalty, and Vien was wise enough not to let Thieu have much evidence. Under Vien's care and protection, Khuyen was ready to sacrifice his life for Vien. Khuyen, on the other hand, was supported by MACV because he always and totally agreed with his American advisor to fulfill his job in supplies management, transportation, storage, and other logistic supports important for successful military operations.
Huong began to focus his investigation on Quang but Thieu made every effort to cover up for Quang to protect himself as his and Quang's dealings were the same. General Hieu compiled and completed the document on Quang and became frustrated. He asked to return to the Army.
Huong was disappointed and gave up persecuting the high ruling officials and, instead, focused on less important civil servants.
Hoang Van Lac and Ha Mai Viet