The Wargames That Prophesized America’s Defeat in Vietnam
It is the early 1960s and America stands at a crossroads in Southeast Asia. President Lyndon B. Johnson is in the midst of a re-election campaign while attempting to grapple with an escalating situation in Vietnam. The South Vietnamese government appears increasingly weak and unstable as the Viet Cong are increasing the tempo of their attacks. As the president weighs his options, many of his top advisers convene in classified rooms in the bowels of the Pentagon basement to play a series of wargames. These were the Sigma Wargames — a series of political-military simulations played from 1962 to 1967. Featuring prominent figures such as National Security Advisor McGeorge Bundy, Chairman of the Joint Chiefs of Staff Earle Wheeler, and Gen. Curtis LeMay, the Sigma Wargames explored potential scenarios for America’s deepening involvement in Southeast Asia. Could the United States bomb the Viet Cong into submission? Could the United States contain the ground war and minimize its own troop losses? Could the United States keep a war in Southeast Asia from escalating?
The games’ answer to these questions was no. No, the United States could not win the war with strategic bombing alone. No, the United States could not fight and win a limited war. And no, the United States would not be able to control how the conflict escalated in Southeast Asia. Over and over again — despite changes in scenario, game rules, and players — the wargame series predicted that U.S. strategic bombing campaigns in Vietnam would lead to a costly quagmire with severe domestic and international political repercussions.
Despite the remarkably prescient and consistent findings, there is little evidence that the wargame series changed key American decisions about Vietnam. Why? And what can these games that didn’t define Washington’s choices in Vietnam teach us about a simmering crisis with China?
A Warning Bell
The Sigma political-military wargames were played from 1962 to 1967, starting under the Kennedy administration and continuing through the Johnson administration. From the beginning, the games were different from the operationally focused military campaign games that usually dominated pentagon wargaming. Instead, these games were designed to explore the intersection of strategy and operations, emphasizing the role that politics, economics, and diplomacy would have on the success of U.S. military options. Game players included senior decisionmakers at the highest levels throughout the U.S. government. The games were rich and complex — each one requiring almost 1000 man-hours to design and execute. Their final reports made it the desks of senior cabinet officials, the results included as a part of decision-making conversations at the National Security Council and State Department. For those that study when and why games matter, the Sigma games seem to have all the characteristics of the type of games that could change the course of history.
To make it more compelling, the findings from the games — despite changes in situational context, players, and game design — were remarkably consistent. Even the first game, played under the Kennedy administration, foreshadowed a long and drawn-out conflict and how successful Viet Cong attrition strategies could be against a United States keen to win while fighting only a limited war. As the 1962 red team explained about their strategy, “our objective was to win even though it might take years, while the Blue’s goal appeared to be not to lose.” The lesson from the game, a full two years before the Gulf of Tonkin incident, was that “if US troops are introduced into such a situation they will be there for some time.”
Even though the games concluded that the crisis would settle into a protracted and bloody conflict, blue’s strategy remained consistent across the scenarios. In all of these games, blue attempted to use air campaigns to bomb North Vietnam (and to some extent Laos and Cambodia) into submission. The hope was that the bombing would not only destroy key targets, but also decrease Viet Cong morale and ultimately cause the regime to crumble. But these strategies were ineffective in the game. As the director of the wargame noted in 1964, “Probably [North Vietnam] could absorb any quantity of punishment [South Vietnam] can currently deliver by air and commando type raids — overt or covert — while continuing to mount pressures in [South Vietnam].” Even in 1966, after the United States had significantly escalated in Vietnam, there was still tremendous debate between blue and control about the air campaign and when or how bombing could bring the North Vietnamese to a truce negotiation.
Finally, the games emphasized the role that domestic and foreign public opinion would play in the conflict. As the Sigma I-64 game report concluded, “It appears necessary that strong backing by US public opinion and Congress be obtained for this concept … in addition to moral and legal questions surrounded undeclared war … there are obvious difficulties in determining the extent of Communist involvement.” In 1966, the control directorate argued that, “public opinion might play a more dominating role, from a US standpoint, than the US Team indicated.”
The games were remarkably influential for many of the players. CIA Director John McCone and Undersecretary of State George Ball both documented how the games decreased their confidence in strategic bombing campaigns and escalation in Vietnam. However, despite this influence, perhaps the most enduring puzzle of these games is how little impact they seemed to have made on the Johnson administration. So far, we have been unable to find evidence that the results of the games ever made it past Defense Secretary Robert McNamara’s desk to Johnson. And even though evidence from the game was used in the highest level of deliberations between State Department and National Security Council, there seems to have been a more vocal group of players that questioned the games’ design and findings. LeMay, Bundy, and even McNamara railed against the games as useless and biased, without “sufficient weight to airpower” and (for McNamara) an example of a flawed over-emphasis on human emotions over rational damage calculations.
Sigma Games Yesterday, Taiwan Games Today
This may be a historical example, but the Sigma game series also holds a warning for the United States today as Washington faces choices about an increasingly bellicose China and turns to wargames to help understand the cost of defending Taiwan. Recent wargames run by think tanks like the Center for a New American Security and the Center for Strategic and International Studies on a Taiwan conflict bare similar warnings for U.S. decision-makers as those foreshadowed by the Sigma games. Like Vietnam, today’s games find that a war with China will be costly, bloody, and difficult to control, a conflict that promises to deplete already waning U.S. munitions stockpiles and test an uneasy stability between two nuclear-armed countries. And, like the Vietnam games, these China games feature prominent U.S. players: congressional members, former under-secretaries, and four-star generals.
But unlike the Sigma games, which were classified and closely held within a coterie of senior decisionmakers, today’s Taiwan wargames are occurring both within the Pentagon and in the public eye. While Johnson may have been shielded from the Sigma game results by those in his staff who didn’t like their results, it would be almost impossible for the White House to miss the contemporary China games that have been documented in the headlines of the Wall Street Journal, Bloomberg, and Meet the Press. There was even a publicized game played by members of Congress.
Games signal to both domestic constituents and adversaries that the United States is serious about a threat, that a state is evaluating what it would take to fight and win a war. They are often the first step in decisions about committing troops or using military force in a crisis. But while games may signal the seriousness of a decision, they cannot always change the mind of decision-makers or budge large bureaucracies (like the Department of Defense).
Further, they are likely to be ignored, suppressed, or discredited when they counter countervailing predilections or desires. Despite current warnings from wargames, the United States has not increased its inventory of munitions or committed troops to Taiwan (or backed away from its ambiguous commitments), nor has Taiwan itself significantly shifted the way it is planning to defend against a Chinese invasion. Entrenched bureaucratic incentives within the U.S. Department of Defense are yet to be moved by the results of these games, and these games have not inspired a public conversation about whether the United States is prepared to spill significant American blood in a conflict over Taiwan.
In 1964, Ball wrote to Secretary of State Dean Rusk about his concerns about escalation in North Vietnam, concluding, “Why are we contemplating an air action against the North in the face of a recently played war game that demonstrated the ineffectiveness of such a tactic?”
Wargames don’t always get the future right, but they can help highlight the risks of different futures and where there may be strategic or operational flaws. Neither the Sigma games nor today’s Taiwan games can answer the difficult question about whether the United States should defend South Vietnam or Taiwan, but both warn decision-makers about campaigns, arsenals, and publics not primed for a long and costly fight.
Dr. Jacquelyn Schneider is a Hargrove Fellow and director of the Wargaming and Crisis Simulation Initiative at the Hoover Institution, Stanford University.
Jacob Ganz is the program manager for the Wargaming and Crisis Simulation Initiative at the Hoover Institution, Stanford University.
Archival materials about the Sigma wargame series are now featured in the wargaming collection at the Hoover Library and Archives and will be explored in a discussion with Lt. Gen. (ret.) H.R. McMaster, Mark Moyar, and Mai Elliott on October 8, 2024.
Image: Yoichi Okamoto via Wikimedia Commons
