Lights Out? Wargaming a Chinese Blockade of Taiwan | CSIS
Lights Out? Wargaming a Chinese Blockade of Taiwan
Report by Mark F. Cancian, Matthew F. Cancian, and Eric Heginbotham
Published July 31, 2025
Since 2022, China has conducted numerous military drills and exercises simulating blockades of the island of Taiwan, a democracy of 23 million that sits astride one of the world’s maritime chokepoints. What would happen if China initiated a blockade of Taiwan in the coming years? To understand the military challenges in countering a blockade, CSIS ran 26 wargames using a wide variety of scenarios.
Although China could inflict serious hardships, particularly by targeting Taiwan’s energy sector, this wouldn’t be a low-risk, low-cost option for Beijing. Any blockade creates escalatory pressures that are difficult to contain and could lead to a large-scale war. Building on existing preparations, Taiwan and the United States could strengthen deterrence by demonstrating that a blockade is not feasible.
This report is funded by a grant from the Smith-Richardson Foundation with assistance from the Diane Davis Spencer Foundation.
Download the report here.
Executive Summary
The year is 2028. Xi Jinping decides, whether because of a long-held plan, internal pressures, or some provocative act by Taiwan, that China needs to apply coercive leverage against Taiwan to change the status quo. He turns to his advisers for options. There are purely economic measures, such as sanctions, but their effects are unreliable and work slowly. In the military sphere, the most dangerous course of action would be invasion: It promises a decisive resolution but risks dramatic defeat. At the other end of the spectrum, China could seize outlying Taiwanese islands, but this might simply push Taipei farther away and draw the United States into closer alignment with Taiwan.
Another alternative, which Xi ultimately decides on, is a blockade in which China attempts to stop shipping headed for Taiwan. Xi orders the China Coast Guard and People’s Armed Forces Maritime Militia to positions around Taiwan, claiming that this is an internal law enforcement matter. After China boards and seizes several ships, commercial traffic to Taiwan ceases. The action disrupts international trade and the world economy. Taiwan rejects China’s legal arguments and decides to resist. What are Taiwan’s military options? Would such a conflict escalate, and what would the military dynamics be at each point of escalation? What would happen to Taiwan’s 23 million citizens? If the United States became directly involved, what would be its military role and prospects?
A potential blockade of Taiwan burst into the U.S. consciousness in 2022 when China showed its displeasure about then–Speaker of the House Nancy Pelosi’s visit to Taiwan by surrounding the island with missile impacts. [1] This report uses the term “blockade” to refer to any Chinese effort using ships, submarines, and aircraft to interdict maritime traffic to Taiwan, rather than as a legal term. For more details about the legal use of the term, refer to “Legal Aspects of Blockade” in Chapter 2. This appeared to simulate a quarantine or blockade. This possibility was not a surprise to regional experts or the Taiwanese themselves, who had long been aware of this threat.
The “joint blockade campaign” (联合封锁战役) is discussed extensively in Chinese doctrinal writing, and the People’s Liberation Army (PLA) has signaled that it would consider such a campaign if it acts against Taiwan.[2] Such a blockade would not just affect China, Taiwan, and the United States. The disruption of international trade, particularly restrictions on computer chip production, would affect every country on the planet.
Given this political and security environment, it would be prudent to study all forms that a Chinese blockade of Taiwan could take in order to inform the policies of Taiwan, Japan, and the United States. Yet, there has been little agreement about what such a blockade would entail, and still less quantitative analysis of possible scenarios.
This report establishes a framework for understanding the range of blockade scenarios, analyzes them with a series of 26 wargames, and assesses the operational challenges that the respective parties would face in implementing and countering a blockade. The project does not argue that conflict, including a blockade, is inevitable or even necessarily likely. However, the project does argue that conflict is possible, given China’s commitment to unification, by force if necessary, and its continuing military buildup. This report, therefore, concludes by proposing policy changes to better deter a blockade and to cope with one should it occur.
A Framework for Understanding a Blockade
In the project’s framework, all scenarios start with a common set of assumptions about the background of conflict: Tensions between the United States and China have increased, with a focus on Taiwan policy. China seeks to resolve (or at least secure major concessions on) its Taiwan problem through a blockade. It establishes an exclusion zone and declares that all ships entering the zone must first stop at Chinese ports for inspection and approval. Ships that refuse are subject to search, seizure, and attack. From there, scenarios diverge according to the escalation levels taken by China and the opposing coalition.
China has four escalation levels:
1. Boarding: China’s nonmilitary forces—the China Coast Guard (CCG), Maritime Security Administration (MSA), and People’s Armed Forces Maritime Militia (PAFMM)—attempt to board and seize merchant traffic to Taiwan without opening fire.
2. Submarines and Mines: China employs submarines and mines to interdict merchant traffic to Taiwan outside of Taiwan’s territorial waters but within the international waters of the exclusion zone.
3. Offshore Kinetic: China employs overt force against merchant ships and escorts outside of Japan’s or Taiwan’s territorial waters but within the exclusion zone.
4. Wider War: The PLA uses overt force not only in the exclusion zone but also against Taiwan itself, the United States, and, potentially, Japan.
Taiwan and the United States also have four escalation levels:
1. Taiwan Constrained: Taiwan restricts its use of military force to its territorial waters and contiguous zone.
2. Taiwan Assertive: Taiwan allows its military to attack Chinese forces that have attacked or attempted to board merchant ships within the exclusion zone.
3. U.S. Constrained: The United States aids an assertive Taiwan with forces that engage in direct combat with the PLA within the exclusion zone.
4. Wider War: The United States attacks PLA forces outside the exclusion zone, including on the Chinese mainland.
Combining the Chinese and U.S./Taiwan escalation ladders produces a matrix (Table ES.1) that describes a range of plausible scenarios ranging from a blockade using only Chinese nonmilitary forces against a constrained Taiwan to a wider war between China and a U.S.-led coalition using all conventional means at their disposal. To examine sensitivity to key variables, the project also explores some variation of assumptions within cells. Blacked-out cells were uninteresting because of the imbalance of forces. Twenty-one game iterations were played using the scenarios and variations within them.
These dyads, or cells in the matrix, are useful analytic snapshots, but it is unlikely that a real-world blockade would stay solely within one of them. There would be escalations and, hopefully, de-escalations. However, examining these dyads separately—without escalation or de-escalation— allows for a more complete assessment of dynamics and advantage at each level of conflict and, therefore, the military incentives for escalation that the respective commanders and political leaders might face under those circumstances.
To better understand escalation dynamics, the project also conducted five free-play iterations to see how players approached the problem when there were no constraints on escalation levels. Thus, there were a total of 26 game iterations.
To analyze these scenarios, the project developed models and simulations that fit into three modules, each answering a critical question:
1. What merchant ships are available for transit to Taiwan? This module identified ships the United States and Taiwan could call upon to run the blockade and the timeline for their availability.
2. How much cargo gets through to Taiwan? The games used three systems depending on China’s escalation level:
▪ ISR and Intercept modeled how many ships would get through a Chinese blockade at lower escalation levels.
▪ Convoy Battle modeled Chinese attacks on convoys and the defense of convoys by Taiwanese, U.S., and, in some scenarios, Japanese forces.
▪ The Taiwan Operational Wargame (TOW), developed for the earlier First Battle of the Next War project, modeled the Wider War scenarios. [3]
3. What is the effect of cargo arrivals on Taiwan’s economy and society? This module has three elements—imports, economic outputs, and effects on Taiwanese society—and calculates these for each week of the blockade.
Project Focus and Scope Conditions
The Taiwan blockade problem is understudied, and this report is not intended to answer all questions. The analysis focuses on the operational problems faced in implementing and countering a blockade, as well as the immediate material impact on Taiwan. To provide context, the literature review section summarizes legal issues associated with blockades, the broader global economic impact that a blockade might have, and illustrative examples of historical blockades.
Several scope conditions also apply. China has decided on a blockade of the island of Taiwan. The project discusses but does not make conclusions about the political and legal debates that would shape the world’s reaction; rather, this project uses scenario variants to explore alternative assumptions about these debates. Taiwan resists. Conflict is limited to conventional domains, and nuclear use is excluded. Finally, there is no use of classified data to allow for the broadest possible dissemination and discussion of the report’s findings.
Wargame Results The project ran 26 wargames. The project did not assign winners or losers; instead, the results specify (1) military losses, (2) how much materiel gets through the blockade to Taiwan, and (3) the impact of those levels of imports on Taiwan’s economy and society. Readers can weigh these results against other societal, diplomatic, and economic pressures on the respective actors to judge political outcomes. Five broad themes emerge from the wargame results:
1. Almost all scenarios entail casualties. Even at lower levels of escalation, casualties were in the thousands. At higher escalation levels, the United States lost hundreds of aircraft and dozens of warships. As in the invasion scenario examined in the earlier First Battle of the Next War project, the lack of air base hardening proved a critical U.S. weakness in the scenarios involving a wider war.4 China’s losses were also high and were often higher than those of the United States.
2. Any blockade creates escalatory pressures that are difficult to contain. In most free-play games, despite a reluctance to escalate, teams responded to perceived escalations with minor escalations of their own and in two games spiraled to a general war. In fixed-escalation games, most dyads produced high casualties and severe economic impacts on Taiwan. There was thus significant pressure on both sides to change the rules of the game and escalate, in turn putting pressure on their opponent.
3. Taiwan requires U.S. intervention if China uses military force in a blockade. While Taiwan’s military was capable of defeating a nonmilitary effort by China (involving the CCG, MSA, and PAFMM), it struggled against even a limited Chinese military effort. Without U.S. intervention, China’s submarines and mines destroyed 40 percent of inbound ships to Taiwan, even with a maximum effort by Taiwan’s military and U.S. resupply of munitions (as has been done for Ukraine). A “Ukraine strategy” was attractive but insufficient when applied to Taiwan because Taiwan’s needs are too great and, in most scenarios, China’s blockade was too tight. If China escalated to using military force, the United States had to accept a Taiwanese capitulation on China’s terms or become directly involved in the conflict. With U.S. intervention, in most scenarios, convoys kept Taiwan supplied, but often at a huge cost.
Any blockade creates escalatory pressures that are difficult to contain.
4. Energy and merchant ships are the critical shortfalls. In all scenarios, natural gas ran out in about 10 days. Taiwan has substantial inventories of coal and oil, but eventually these ran out also if not resupplied (at 7 weeks and 20 weeks, respectively). Food was not a problem because of what Taiwan produces domestically, its large inventories, and the modest shipping requirements to make up shortfalls. Rapidly acquiring ships to run the blockade was critical because regular shipping companies would not take the risk of getting involved if China begins a blockade. Airlift, submarines, and small blockade runners were inadequate substitutes for cargo ships. These alternatives could provide only a small percentage of Taiwan’s regular daily deliveries.
5. A blockade is not a “low-cost, low-risk” option for China. Casualties were high across almost all dyads, and the incentives for escalation were always present. Two free-play games reached maximum escalation, with U.S. missiles striking the Chinese mainland and Chinese missiles striking Guam and Japan. In these and other high-escalation scenarios, the combination of U.S. bombers launching standoff missiles, submarines operating offshore, and, to a lesser extent, U.S. tactical aircraft and surface ships proved devastating against Chinese military assets. Blockade was likewise not a good precursor to invasion because the aggressive action put other countries on alert and, in some cases, resulted in the loss of Chinese assets that would be needed in the event of invasion.
Recommendations: Preparing for and Countering a Blockade
This project does not take a position on the likelihood of Chinese military action or on whether the United States should defend Taiwan should Chinese military action occur. However, to the extent that the United States maintains even an ambiguous commitment to Taiwan, it should be prepared to act, should the president decide to do so. Based on the wargaming results and insights, the project developed a set of recommendations for decision makers. These recommendations have three goals: (1) to enhance deterrence by showing China that Taiwan and the United States are prepared and cannot be coerced, (2) to allow faster reaction times and produce more effective counter-operations in an emergency, and (3) to discourage other countries from pressuring Taiwan to submit because they hope that a quick resolution would restart normal commerce. The recommended actions did not always thwart a blockade, but they would buy time for a diplomatic solution or outside intervention.
1. PREPARE THE MERCHANT FLEETS.
The number and type of merchant ships that arrive in Taiwan will largely determine material conditions on Taiwan, which will in turn shape the outcome of a blockade. Therefore, the most important measure for pre-conflict preparations is to increase the availability of merchant ships that can make the hazardous run into Taiwan.
▪ Arrange for mobilization of Taiwanese-owned shipping. The fleet of Taiwanese-owned ships is much larger than the fleet of Taiwanese-flagged ships. Therefore, Taiwan should ensure that all ships whose beneficial owners are Taiwanese are legally subject to requisition in an emergency.
▪ Contract liquified natural gas (LNG) tankers into the Voluntary Intermodal Sealift Agreement (VISA) program and create a Taiwanese equivalent. Because LNG tankers are the greatest shortfall in energy delivery, both the United States and Taiwan should acquire LNG tankers to hold in reserve for emergencies.
▪ Make plans for managing war risk in the commercial sector. In an emergency, both Taiwan and the United States will need to replace or supplement commercial insurance with guarantees, subsidies, or “reinsurance” to keep maritime and air traffic flowing.
▪ Plan for transshipment in Japan, Guam, and Australia. Because presumably only ships controlled by the coalition countries will travel to Taiwan during a blockade, there needs to be a place where commercial traffic can transfer cargo to coalition-controlled ships to make the shuttle run into Taiwan. Japan is preferable because it is closer and has excellent port facilities, although ports in Australia and Guam could help. The United States, Taiwan, Japan, and Australia should develop plans for such transshipment points in advance.
2. PREPARE TAIWAN’S ENERGY INFRASTRUCTURE.
Energy is the weakest element in Taiwan’s resilience against coercion. The overwhelming preponderance of energy must be imported and is thus vulnerable to a blockade.
▪ Increase Taiwanese energy reserves. Taiwan has done a lot to enhance resilience, particularly with its reserves of oil and coal. Additional inventories could come from building more storage facilities or filling the existing logistics chains on the island before a crisis.
▪ Maintain and expand resilient energy sources. Taiwan has shifted its sources of energy from coal and nuclear to natural gas and renewables for environmental reasons, but this has greatly increased Taiwan’s energy vulnerability. Taiwan should keep its last nuclear power plant open and capitalize on new technologies to produce safe nuclear energy.
▪ Harden energy infrastructure. Taiwan has already made its electrical system more resilient in the face of extreme weather conditions. More hardening is needed for national security reasons.
▪ Expand plans for allocating resources on Taiwan. To ensure the most effective response during an emergency, the Taiwanese government will need to control imports to focus on the most critical items and distribute them to activities with the greatest need. A free-for-all would reduce resilience and undermine the legitimacy of the government’s response
3. PREPARE CONTINGENCY PLANS FOR THE UNITED STATES TO ASSIST TAIWAN DURING A BLOCKADE.
In most scenarios, Taiwan cannot face China alone. If the United States wants to have the capability for keeping Taiwan autonomous and democratic in the face of a Chinese blockade, then it should have plans ready to support Taiwan at a variety of blockade levels.
▪ Rebuild skills and prepare contingency plans to conduct convoys during a blockade. The U.S. Navy is out of practice because convoys have not been a priority mission since the end of the Cold War. Rebuilding these skills will require wargames, training programs, and peacetime exercises with allies and partners. Rebuilding will also require peacetime planning for establishing a convoy system.
▪ Make joint plans with allies and partners, especially Japan. The United States will need the support of allies and partners in any conflict with China. Therefore, it should conduct planning now with allies and partners on possible blockade scenarios. Japan is critical in nearly all scenarios and deserves special attention. The United States also needs to align its other policies with its national security priority of competition with China. Otherwise, it may find that allies and partners hang back at the time of need.
▪ Make contingency plans for an airlift and military resupply of Taiwan while recognizing the severe limitations of these options. U.S. Transportation Command (TRANSCOM), in conjunction with U.S. Indo-Pacific Command (INDOPACOM), needs to have at least concept plans for an airlift, given the centrality of China in U.S. military planning. In conjunction with other measures, an airlift could potentially complicate China’s blockade problem. The president might not execute an airlift or military resupply because of its high cost, political risks, and low deliveries, but TRANSCOM would be derelict in its duties if it did not have plans in place.
4. PREPARE TO COUNTER AND END A BLOCKADE.
If deterrence fails and the United States decides to counter a Chinese blockade, the United States, in coordination with Japan and Taiwan, must be prepared to respond based on plans made well in advance.
▪ Do not treat a blockade like an invasion. Countering a blockade differs from countering an invasion and requires different planning. For example, direct military action against Chinese forces could wait for a week or two until a military and diplomatic coalition can be established.
▪ Provide Beijing with off-ramps. The United States and Taiwan should develop a creative menu of offers and responses ahead of time that could allow China to declare victory and lift the blockade without extracting substantive concessions.
Observations Across Three Projects
This project is the third in a series of studies conducted by the authors on China’s threat to Taiwan. In all, these projects have run over 70 wargame iterations covering dozens of scenarios, providing a broad view of what might happen in a U.S.-China conflict over Taiwan. There are several common elements in the recommendations across the three projects:
▪ Even successful campaigns exact heavy casualties, such a conflict would be a shock to the United States, which, since the end of the Cold War, has been accustomed to fighting low-casualty wars with few losses of major weapons.
▪ Off-ramps are valuable because total victory is unachievable when both sides have a secure homeland and nuclear weapons.
▪ Strong military forces provide the United States with options and, combined with skilled diplomacy, contribute to deterrence.
▪ Military operational planning needs to include a broad scope of possible scenarios. Planning is a tool for better senior-level decisionmaking, not a statement of intent to wage war.
▪ Above all, the unexpected can happen. Although war with China is unlikely, it is not impossible, and unlikely events occur. Preparation is vital.
There are also some tensions between preparations for different contingencies. Preparing for a high-intensity conflict drives Taiwan to adopt a porcupine strategy that relies heavily on defensive systems like ground-based antiship missiles, ground-based air defenses, and sea mines. Countering blockades, on the other hand, requires surface ships, aircraft, and some offensive capabilities.
The bottom line across three projects: the United States in coordination with its allies and partners must be prepared to deter and, if necessary, fight a wide variety of scenarios. There is no magic bullet that can bring success across all scenarios. Instead, success requires a deep toolbox of capabilities.
[1] This report uses the term “blockade” to refer to any Chinese effort using ships, submarines, and aircraft to interdict maritime traffic to Taiwan, rather than as a legal term. For more details about the legal use of the term, refer to “Legal Aspects of Blockade” in Chapter 2.
[2.] See, for example, the 2006 version of the Science of Campaigns, in which the Joint Blockade Campaign is one of only three joint campaigns that receive treatment in a separate chapter. 张玉良 (Zhang Yuliang), ed., 战役学 [Science of Campaigns], National Defense University Press, May 2006.
[3] Mark F. Cancian, Matthew Cancian, and Eric Heginbotham, “Chapter 3: Building the Taiwan Operational Wargame,” in The First Battle of the Next War: Wargaming a Chinese Invasion of Taiwan (Washington, DC: CSIS, January 2023), 40–52, https://www.csis.org/analysis/first-battle-next-war-wargaming-chinese-invasion-taiwan.
[4] Ibid.
