What the War Games Say: The Simulations That Are Shaping Taiwan Contingency Planning
The Center for Strategic and International Studies published a major wargame analysis of the Taiwan Strait in January 2023. It ran 24 iterations of a Chinese invasion scenario, varying assumptions about Chinese military capability, American intervention, Japanese participation, and Taiwanese defense posture. The headline finding — that the United States and its allies could likely defeat a Chinese invasion but at very high cost — made international news. The details of the analysis were more nuanced and more alarming than the headline suggested. Understanding what the wargames actually show, and what they cannot show, is prerequisite to understanding the current state of Taiwan contingency planning.
The CSIS analysis found that in most scenarios, the United States and Taiwan could defeat a Chinese amphibious assault and preserve Taiwan’s de facto independence. The victory, however, came at costs that were consistently described as severe: the United States lost two aircraft carriers and dozens of surface ships in most scenarios; Taiwan’s air force and navy were substantially destroyed in the first weeks of conflict; Japan, which provided essential basing in the scenarios where Taiwan survived, took heavy casualties and significant infrastructure damage; and the economic disruption from the conflict, estimated separately, was catastrophic. The analysis was explicit that the “victory” produced outcomes that would leave all parties diminished.
The scenarios where Taiwan lost — where the PLA successfully established a beachhead and began the process of occupation — typically involved specific conditions: slow American response that allowed PLA forces to consolidate before intervention could be effective; Japan declining to provide basing or failing to authorize American use of Japanese facilities; Taiwan’s ground defense collapsing faster than the military assessments of its capability predicted; or particularly effective PLA missile campaigns that destroyed American basing infrastructure before American air power could be effectively deployed. Each of these adverse conditions is plausible. None is inevitable. The wargame’s contribution is identifying which variables most determine the outcome.
The RAND Corporation’s prior wargame analyses — particularly from the early 2010s, when RAND began publishing assessments of the changing military balance — were among the first to highlight publicly that the military competition was no longer as one-sided as the 1996 crisis had suggested. RAND’s analysis identified the A2/AD investment program as a genuine challenge to American military superiority in the western Pacific, at a time when the political implications of this assessment were not comfortable for American defense planners. The analysis proved prescient. The military balance that RAND described as emerging in the early 2010s is the balance that exists today.
The limitations of wargames deserve acknowledgment. They model the variables that modelers can quantify: force sizes, weapons capabilities, logistics throughput, reaction times. They do not model the political variables that may be more important: the decision-making processes of specific leaders under conditions of fear and incomplete information, the domestic political constraints that shape whether and how military forces are committed, the communications failures and misidentifications that have historically been central to how wars begin and escalate. A wargame that produces a clear outcome depends on assumptions about political variables that are not knowable in advance and that may not hold in the actual crisis.
The Japanese participation variable is perhaps the most consequential unresolved assumption in most Taiwan wargames. Scenarios in which Japan provides full basing access and authorizes American use of Japanese facilities for offensive operations against Chinese forces produce materially better outcomes for Taiwan than scenarios in which Japan is passive. The political decision that would determine Japan’s actual posture in a real crisis — a decision that would be made under enormous time pressure by a government operating within a constitutional and domestic political framework that has been changing — is exactly the kind of variable that wargames must assume rather than model.
The wargames have been doing their job: producing planning insights, identifying critical vulnerabilities, and forcing decision-makers to confront scenarios they would prefer to avoid. Whether the decisions that result from that confrontation are adequate to the risk the scenarios reveal is a different question.