After the 1954 Geneva Accord, which cut Vietnam in two at the 17th parallel, the North was given to the Viet Cong (Vietnamese Communists), and the South to the Nationalists. Because right at the outset, the Viet Cong had the intention of invading and conquering South Vietnam through military means, they established and expanded an intelligence network in the South.
At first, they did not regroup all their troops to the North, and retain numerous cadres in the South who managed to infect the admistrative and miltary apparatus of the South Vietnamese government. Then, a certain numbers of Viet Cong in the North feigned to abandon the Communist Party and followed the refugee waves down to the South; or in a few instances, some crossed the Hien Luong bridge at Ben Hai river under a staged escape completed with make believed gunfires of the border guards. Finally, they used family ties and relationship of Northerners and Southerners, to recruit nationalist members to become spies.
After the fall of Saigon in May 1975, Viet Cong moles emerged, among them are some notorious ones, such as Vu Ngoc Nha, presidential advisor (wearing the rank of major general at his death in 2002)̣, Pham Xuan An, correspondent of foreign news agencies (real name Tran Van Trung, currently a major general), Nguyen Huu Hanh, ARVN Brigadier General (currently a member of the Central Committee of National Front League of Vietnam), Nguyen Thanh Trung, VNAF F5E pilot (currently vice president of Air Vietnam).
High ranking military leadership in the ARVN was keenly aware of the fact Viet Cong moles were inserted at all levels and consequently was extremely vigilant. Although personnel assigning to the general staff were carefully screened and closely monitored by the Military Security Bureau, the commanding generals of division and corps were still concerned. This situation caused generals of the ARVN to act quite differently as compared to generals of other armies in order to maintain secrecy.
General Nguyen Viet Thanh
General Abrams recounted that General Thanh, in order to preserve secrecy, designed in person the operational plan on a piece of paper, tucked it into his shirt pocket, only showed it to the divisional commander of the operation and warned him not to reveal it to anybody including his general staff. Then on the operation launching day, General Thanh seized the operational command of the battle:
General Ngo Dzu
General Abrams recounted further that when he visited II Corps, General Ngo Dzu, instead of briefing him on the military situation at the corps headquarters, took him directly to his residence, where he hanged tactical maps all over the walls, out of the sight of his own general staff:
General Nguyen Van Hieu
In 1965, when General Vinh Loc entrusted him with the planning of the road clearing operation of QL 19, Colonel Hieu set as first priority the secrecy of this operation named Than Phong II, limiting its knowledge to himself and General Vinh Loc. Despite the fact of having to maneuver simultaneously huge units comprising 22nd Infantry Division, 3rd Armored Battalion, 2nd Airborne Task Force, Regional Force units, Civilian Irregular Defense Group units, Alpha Marine Corps Task Force and 42nd Regiment, 20th Combat Engineer Group and one Ranger battalion, Colonel Hieu succeeded in “maintaining maximum secrecy about the operation, even within the staff”, and the three NVA 32nd, 33rd and 66th Regiments were caught pants down and unable to react.
General Hieu accomplished a greater success regarding secrecy in a bigger operation, involving a force equivalent to three divisions belonging to III and IV Corps. Following is a brief summary of Svay Rieng Operation as recounted by Colonel William LeGro:
The main factor contributing in the success of Svay Rieng Operation was secrecy, in combination with two other factors: speed and coordination of a multifacet force. Participating units in the battle performed their duties as designed by General Hieu, but were not aware of the whole picture of the operation, even their respective commanders saw only pieces of the action as allowed by their limited participations. This explains the fact General Tran Quang Khoi, III Corps Assault Task Force (IIICATF) Commander, when he received the order from III Corps Commander to dispatch tanks of his IIICATF into Kampuchea, naively thought he was the field commander of the battle and stated that there was never an operation called Svay Rieng Operation, there was only the counter-offensive operation of IIICATF at Duc Hue base camp̣.
It is for this same concern of maintaining absolute secrecy that General Hieu did not reveal to anybody his counter-offensive plan to contain the advance of Communist troops pouring down into III Corps that he had ready in his head. When I asked Colonel Phan Huy Luong, Assistant to III Corps Deputy Commander of Operations, "Did General Hieu discuss with you about his plan to defend Saigon? ", his response was, "No, he did not. The two Generals only conferred among themselves."
General Lam Quang Tho
General Lam Quang Tho, as Superintendent of the Dalat National Military Academy, had also to deal with counter-intelligence matters, because colonel chief of staff at the Academy was a Viet Cong mole. In one hand, he had the Military Security Bureau monitored his man; in the other hand, he secretly entrusted Lieutenant Colonel Tran Van Thuong, Organization Bureau Head in his General Staff, the task of defense measure to be taken in case of enemy attack on the premises:
After April 1975, the chief of staff Viet Cong mole emerged without his cover.
Besides the vigilance toward spying as shown by the above-mentioned general officers, quite a sizable number of other generals in the ARVN sinned pitifully in this regard. Intelligence and counter-intelligence professionals generally make use of human weaknesses in morality to gather intelligence. Besides the four common sins of drinking, womanizing, gambling, and smoking opium, the Communists exploited the superstition and soothsayer's consultation inclination of some ARVN generals. In particular, Communist spies disguised as soothsayers to either extract indiscretions or to influence on the date and direction of an operation or even its tactics when a general heavily addicted to superstition come to consult them, and then communicate this intelligence information to the enemy military establishment. It was indeed a huge gaff, because in a battle, whoever has the upper hand in intelligence matter will prevail the enemy.
Nguyen Van Tin