Missing the Jungle for the Trees

Headline: Missing the Jungle for the Trees

Deck: How US Intelligence Underestimated the Tet Offensive and Lost the Vietnam War

Author(s): Dmytro Sochnyev

Group: EPIS Magazine

Overall Summary: The Tet Offensive of 1968 provides an excellent case study of how even disadvantaged actors can succeed when underestimated. By exploiting the perceptions of the opponent and the pervasive eye of modern media, a dangerous vulnerability can quickly turn into strategic defeat.

Highlight Sentence: “Whether from overconfidence, ignorance, gullibility or just a failure to comprehend the facts, military defeat is almost invariably associated with an intelligence defeat.”

Word Count: 2997

The Tet Offensive

Know the enemy and know yourself; in a hundred battles you will never be in peril.

—Sun Tzu (Griffith, 1971)

“Crack the sky, shake the earth” was the command given to over 84,000 fighters of the People’s Army of Viet Nam (PAVN) and communist Viet Cong (VC) revolutionaries in South Vietnam in the early morning of January 30th, 1968 (Brimelow, 2021). The Tet Offensive, also known as the Tong Cong Kich/Tong Khoi Ngia (TCK/TKN) or General Offensive–General Uprising in Vietnamese, caught the allied forces of the US Military Assistance Command Vietnam and the South Vietnamese Army of the Republic of Vietnam (ARVN) completely off guard.

Instead of observing a ceasefire for Tet, the Vietnamese Lunar New Year, VC units infiltrated cities and outposts from within the Republic of Vietnam (RVN) in the south, while PAVN units stormed across the Cambodian border and Demilitarised Zone (DMZ) from without. Except for a few VC brigades that were unaware of a 24-hour delay (Prados, 1993), the offensive was initiated across the country almost simultaneously. 36 out of 44 Southern Vietnamese population centres were assaulted, including the previously untouched RVN capital, Saigon (Brimelow, 2021). This radical departure from irregular tactics to a more conventional offensive aimed to catalyse a popular uprising among the Southern Vietnamese, engulf the Allied forces in bloody urban fighting and potentially overthrow the South Vietnamese government to force a negotiated withdrawal of US forces and a subsequent communist takeover.

On the military level, the Tet Offensive was admittedly a tactical catastrophe. Despite initial successes, PAVN forces were decimated by overwhelming American firepower, especially while defending captured positions. The VC displayed an unprecedented level of offensive coordination, but sacrificed the bulk of their offensive potential for the rest of the war. US and ARVN forces successfully counterattacked, and within two months had returned virtually all of the territory they had ceded. The North Vietnamese even failed to trigger the popular uprising they had expected in the wake of the offensive and grossly underestimated the strength and resilience of the ARVN (Pribbenow, 2008).

On the political level, however, the Tet Offensive remains the seminal moment for US withdrawal. After several years of guerrilla fighting had ground to a positional fight, the PAVN and VC had delivered a daring strike quite literally into the homes of oblivious US and South Vietnamese coalition forces. The offensive was widely televised to horrified viewers back in the US, including the inconceivable infiltration of the American embassy in Saigon on the second day (Robbins, 2010). After Walter Cronkite, CBS news anchor and the “most trusted man in America”, returned after the Tet Offensive in February to tell the nation that the war had regrettably become a stalemate, US President Lyndon B. Johnson allegedly told associates, “If I've lost Cronkite, I've lost Middle America” (Wicker, 1997). Johnson would refuse to seek reelection in the 1968 electoral campaign, thereby abandoning responsibility for the war to the next administration.

What had occurred was a tremendous underestimation by the leadership of the US FORCES under General William C. Westmoreland. Despite US and RVN intelligence collecting considerable elements of information indicating the intent, scale and even direction of a significant North Vietnamese attack, the early warning was missed due to fundamental misconceptions about the nature of the adversary, the war, and the American public. The consequences of the underestimation proved catastrophic in the long run: the episode obstructed political support for the escalation of American commitment previously feared by the North Vietnamese and shattered public perceptions about the war.

The Political Calculus of Hanoi’s War

In retrospect, the communist Vietnamese had made visible a vulnerability that American strategists, policymakers, and generals have struggled to correct since the withdrawal of US forces from Vietnam. As James Robbins (2010) argued, the Tet Offensive is an inspiration for asymmetrical foes who, by using sudden and unanticipated violence, can facilitate potentially fatal political costs regardless of the achievement of immediate tactical objectives. The American politician is fundamentally risk-averse and wants short, winnable conventional wars with low, measurable costs, not protracted, low-intensity stalemates. Shock attacks introduce an uncomfortable uncertainty that complicates the former and threatens the latter. So long as the adversary can then maintain fighting, the US will eventually be compelled to fold. The Americans may have the watches, but their adversaries have the time (Nagl, 2022).

In practice, the US’s adversaries have repeatedly reaffirmed what they view, according to Robbins, as its “Achilles heel” (2010, 51). In June 2004, then US Secretary of Defence Donald Rumsfeld said that Iraqi insurgents had “read about Tet and the fact that if they make a big enough splash, even though they get a lot of people killed and we pound them, they end up winning psychologically” (Robbins, 2010, 54). In 2006, Hassan Nasrallah, then leader of Hezbollah, was inspired by the “lesson of Vietnam” when he argued that the US would leave the Middle East “like they left Vietnam” and abandon those who placed their trust in the US “to their fate, just like they did to all those who placed their trust in them throughout history” (Robbins, 2010, 51-52). More recently, Russian political commentary claimed that victory in the war against Ukraine involves simply waiting out the supply of Western military aid (Soltys, 2023).

Back in 1968, the Communists had yet to test this vulnerability, but similar thinking had been familiar to them for decades. The Tet Offensive concept was first referenced in 1947 in the context of the decolonisation struggle in French Indochina, where Party Secretary Truong Chinh envisioned that their final victory would be achieved through widespread attacks on urban centres coordinated with fomented uprisings. Even though French withdrawal was secured after victory at Dien Bien Phu and not in the cities as Chinh had predicted, the Communists nonetheless believed that domestic disenchantment was the critical factor for this “decisive victory” (Ford, 1995). The Communists had considered an operation similar to the Tet Offensive based on these principles as early as 1960 but worried about American escalation and the readiness of the VC. As the war progressed, both of these factors were less applicable, and the vulnerabilities of the US became more apparent. In April 1966, PAVN General Nguyen Van Vinh argued to his VC counterparts that:

In a war of position, they can defeat us. But with our present tactics, we will win and they will be defeated. It is the same as if we force them to eat with chopsticks. If we eat with spoons and forks like them, we will be defeated; if chopsticks are used, they are no match for us. (Ford, 1995, 66)

Leading up to the Tet Offensive, the Vietnamese communists were motivated and far from capitulation. But the fighting had already proven costly, with American bombing campaigns decimating Northern Vietnamese populated areas and displacing hundreds of thousands. The Communist Party’s assessment before 1968 was that while they had successfully managed to prevent an American victory, they were also unable to achieve their own victory.

By July 1967, the Politburo resolved that a vigorous and sudden attack was needed to win the war before Americans could commit more resources and overwhelm the precarious strategic balance (Guan, 1998). It officially adopted the strategy in Resolution 13 that month and began to prepare officers in the necessary tactics (Guan, 1998). The turnaround from theory to plan was hasty but understandable. Hanoi was cognisant that the American elections in late 1968 would present a brief opportunity to “force the American ruling circles to make a decision on whether or not to end the war” (Ford, 1995, 64). The objectives of this upcoming phase of “winning decisive victory” were finalised in early January 1968 at a plenary session of the Communist Party’s Central Committee (Guan, 1998). Firstly, the Communists needed to exploit a strategic opportunity to shift the war from the stalemate. Secondly, they had to stretch US and ARVN units away from the urban targets. Thirdly, they had to deal a “thundering blow” to change the “face of the war” and compel the US to de-escalate and seek a negotiated withdrawal (Guan, 1998, 351).

Underestimation, the Child of Cognitive Dissonance

The Tet Offensive was thus not merely a reaction to the realities of the war but an inevitability derived from deep within Vietnamese strategic thinking. Certainly, direct insights into an adversary’s high-level thought are a difficult task for espionage, but more scrutiny of the circumstances up to January 1968 could well have laid bare Hanoi’s plan. But, as Col. John Hughes-Wilson explained:

In the great majority of cases, defeat can usually be traced back to a lack of knowledge of the enemy. Whether from overconfidence, ignorance, gullibility or just a failure to comprehend the facts, military defeat is almost invariably associated with an intelligence defeat. (Hughes-Wilson, 1999, 3)

American underestimation was no different. Cognitive dissonance simply prevented US FORCES and the Combined Intelligence Centre (CIC), the main joint American-South Vietnamese intelligence unit, from discovering the decisive victory strategy or providing early warning for such a manoeuvre. These conceptions persisted despite repeated evidence supporting a large-scale buildup. The CIC had evidently drawn few lessons when similarly erroneous assumptions by Israel’s military intelligence wing made them fail to predict the surprise attack by Egypt and Syria on Yom Kippur a year before (Kahana, 2002).

Indeed, although the Politburo stressed the importance of operational secrecy (Guan, 1998), the Communists would find it impossible to hide the buildup and planning of a strategic operation of that magnitude. As Carl von Clausewitz once noted:

Surprise is a tactical device, simply because in tactics time and space are limited in scale. Therefore in strategy, surprise becomes more feasible the closer it occurs to the tactical realm, and more difficult, the more it approaches the higher levels of policy. Preparations for war usually take months. Concentrating troops at their main assembly points generally requires the installation of supply dumps and depots, as well as considerable troop movements, whose purpose can be guessed soon enough. It is very rare therefore that one state surprises another, either by an attack or by preparations for war. (Clausewitz et al., 1989, 198-199)

American intelligence thus observed a gradual increase in infiltration of South Vietnam and an increase in shipments observed along the Ho Chi Minh Trail, from 55 trucks in September 1966 to between 695 and 4,235 in December 1967 (Prados, 1993).

On numerous occasions, the CIC was also gifted captured documents that put the Tet Offensive’s operational secrecy in jeopardy. A document captured by the ARVN in October 1967 explicitly mentioned the Tet Offensive and plans for an offensive coinciding with a countrywide uprising. In November, a military directive by the South Vietnamese communists was uncovered that mentioned the North Vietnamese intended to goad the redeployment of American troops away to the border with coordinated attacks (Prados, 1993). Then a low-ranking cadre was captured with the “Quang Tin Document,” an order that indicated Hanoi perceived US political will as sufficiently weak to make a "decisive victory" possible (Ford, 1995). A week later, the contents of a captured notebook mentioning Resolution 13 and emphasising a “general counteroffensive and general uprising” ordered by Hanoi were circulated multiple times between November and early January (Prados, 1993). A potentially deliberately misleading directive was captured on December 16th calling for the use of the Tet holiday truce for resupply and training and, ironically, became part of a press release in January called “Captured Document Indicates Viet Cong Plan to Take Advantage of Cease-Fire” (Prados, 1993).

In January in particular, the intelligence was almost farcically revealing. Documents were captured revealing attack plans for specific cities in the South. A group of VC were captured by RVN counterintelligence with a tape recording to be broadcast over the radio that claimed the major cities of Hue, Da Nang and Saigon were already controlled by the VC. On January 28, human intelligence revealed VC artillery and infantry regiments prepared to assault Bien Hoa. Some North Vietnamese even attacked a day before the planned start date for the Tet Offensive (Prados, 1993). All in all, the Americans and South Vietnamese had considerable and often explicit intelligence revealing the existence, timing and location of the Tet Offensive.

Yet these early warnings went unheeded because entrenched opinion in American command was that the PAVN and VC were both too attrited and operationally incapable of an offensive of such a scale (Guan, 1998; Ovodenko, 2011). Gen. Westmoreland boasted that the rate of replacement of North Vietnamese casualties was negative enough that the US could plan for victorious withdrawals in 1969 (Prados, 1993). However, these casualty and ‘order of battle’ estimates used either insufficient data or were deliberately manipulated to bolster domestic support (Wirtz, 1991; Ovodenko, 2011). Communist intentions derived from document captures were dismissed as either indoctrinated propaganda or not substantially departing from previous statements and intelligence earlier in the war (Ovodenko, 2011). Analysts in the theatre, like those at the Saigon Station, were also accused of overreacting to speculation (Ford, 2024).

Eventually, as the rate of assaults rose and the intelligence grew increasingly unsettling, Gen. Westmoreland shifted focus to Khe Sanh near the DMZ, where PAVN troops were expected to launch a siege in early January 1968, mimicking the infamous battle of Dien Bien Phu (Ovodenko, 2011). In reality, the imminent assaults were part of a larger deception strategy, as outlined in some of the captured documents, to redeploy troops away from urban centres and to see whether US forces might respond with an incursion into North Vietnam itself (Ford, 1995). The Communists were wilfully playing into American conceptions of a desperate enemy and further diverting attention away from the Southern areas they intended to target (Prados, 1993; Ford, 1995). When Gen. Westmoreland responded to the Khe Sanh assaults in mid-January with reinforcements and massive aerial bombing—but no counterattack to the north—the PAVN were reassured of their strategy.

Some voices attempted to raise alarm. David Mozingo wrote a paper in 1966, based on open-source texts and captured intelligence, for the RAND Corporation in which he surmised that the Communists would switch to large, mobile offensives to create intense political pressure (Elliott & Thomson, 2010). Mozingo argued they believed they could trigger the collapse of a weak RVN and accelerate US withdrawal by confronting Washington with an endless war. His analysis was rejected, despite largely relying on evidence from the Communists themselves, because it contradicted the conventional wisdom that the PAVN and VC were depleted. Likewise, the CIA’s Saigon Station predicted an unprecedented “all-out attack”, even explicitly referring to the Tet Offensive by name and unwittingly concluding that the “outcome of the 1967-68 winter-spring campaign will in all likelihood determine the future direction of the war” (Prados, 1993, 174). It is possible that much of this intelligence was simply ignored. “It is revealing that President Johnson’s memoirs,” said former NSC staff officer C.L. Cooper in 1984, “which are replete with references to and long quotations from documents which influenced his thinking and decisions on Vietnam, contain not a single reference to a National Intelligence Estimate or, indeed, to any other intelligence analysis (Ford, 2024, 38).

General Frederick Weyand, tasked with the defence of Saigon, and Captain Robert Simmons discovered that the VC had reorganised their command zones in wedges pointed directly at the capital just before the Tet holiday. Gen. Weyand subsequently managed to convince Gen. Westmoreland to redeploy at least some battalions to defend Saigon, a decision the latter called “one of the most critical of the Vietnam War” (Ovodenko, 2011, 133). Nonetheless, half of South Vietnamese personnel were granted holiday leave, so many ARVN units were only at 10-20% strength (Prados, 1993). On the night of the Tet Offensive, many key senior US officers, including Gen. Westmoreland, awoke to the sound of shooting just outside their residences. Col. George Jacobsen, a senior CIA official living in the Saigon embassy, defended himself with a pistol after VC broke into the compound (Prados, 1993).

Conclusion

The Tet Offensive illustrates a deeply perplexing situation: military intelligence had potent evidence of upcoming hostile operations, the general staff was keenly aware an attack was imminent, and yet stubborn myopia prevented military and political leadership from seeing the larger picture. Underestimations of PAVN/VC strength, resolve, and war aims persisted despite collected intelligence that contradicted entrenched conceptions. The intelligence was so glaring in hindsight that some officers involved in the failure would later have the audacity to claim that they knew all along. “We were not surprised by the fact of the Tet Offensive,” said General Daniel O. Graham to a congressional committee in 1975, “what surprised us was the rashness of the Tet attacks” (Prados, 1993, 161-162).

The corollary lesson is that the Tet Offensive represented a significant intelligence success for the North Vietnamese. Although relatively lacking in intelligence-gathering and resources, they accurately estimated their adversary’s vulnerabilities and formulated an ambitious strategy to take advantage of them and exploited American preconceptions to deceive US forces and deny them the ability to prepare appropriately. Admittedly, the Tet Offensive was a desperate and extremely costly gamble, and Communist intelligence itself erred in some tactical and strategic respects, but it was successful in the long run.

The contemporary and future consequences for American foreign policy were enormous. Not only was Tet a crucial blow to the US’s capacity to fight the war, but it undermined their ability to fight future wars as well. US General Jack Keane noted in 2006:

After the Vietnam War, we purged ourselves of everything that had to do with irregular warfare or insurgency, because it had to do with how we lost that war. In hindsight, that was a bad decision. (Nagl, 2022, 15)

The PAVN and VC not only succeeded in their war aims, but also unknowingly forced into existence a prism through which every subsequent strategic American setback would inevitably be viewed.

References

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