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Under the Nuclear Shadow
September 2025
The Logic of Strategic Substitution
Under the Nuclear Shadow
By Fiona Cunningham
Princeton University Press, 2025
Reviewed by Elsa B. Kania
Under the Nuclear Shadow is a critical contribution to understanding the rationales informing China’s military force posture and evolving approach to deterrence. Author Fiona Cunningham introduces a theory of strategic substitution and uses it to examine the logic behind China’s drive to develop information-age capabilities. As the Chinese People’s Liberation Army (PLA) faces the limited war dilemma of defining the challenge of achieving objectives through military force while mitigating risks of nuclear conflict, its pursuit of coercive leverage has motivated significant investments and transformation of its force posture. In particular, Chinese leaders and military strategists have regarded the development of information-age capabilities, especially in advancing cyberspace operations, counterspace weaponry, and precision conventional missiles, as uniquely advantageous, given their greater flexibility and potential for improved credibility. The strategic rationales and historical perspectives that this book provides are invaluable to our understanding of the contours of Chinese military power.
China’s Search for Leverage
The book traces the trajectory of China’s military modernization and examines several critical inflection points in which “leverage deficits” provided an impetus for Chinese leaders to prioritize pursuing certain information-age capabilities. In particular, the 1995-1996 Taiwan Strait crisis, when the U.S. military deployed aircraft carriers off the coast of Taiwan in response to China’s attempted coercion, and the 1999 Belgrade embassy bombing, which Beijing believed to be deliberate, can be regarded in retrospect as moments when Chinese leaders became acutely aware of shortfalls in their capabilities relative to the United States. These realizations created catalytic impacts driving Beijing’s decision to develop capabilities that Washington, regarded as a powerful potential adversary, could fear. While Cunningham characterizes these moments primarily as political crises, the military motivations and considerations are closely entwined, especially after factoring in the singular demonstrations of U.S. military capability in each instance.
The theory of strategic substitution is presented as a puzzle and a unique choice by China to pursue an alternative approach relative to adopting a nuclear-first-use posture (brinksmanship) or to develop superior conventional capabilities. By contrast, China decided to bet on information-age capabilities, here defined as cyberspace, counterspace, and conventional precision missile capabilities. This approach could be regarded as highly risky yet pragmatic; Chinese leaders were willing to bet on new domains and more untested technologies, yet also regarded these specific capabilities as quicker, feasible options for accelerated development relative to more conventional alternatives.1
This book provides a deeply researched and authoritative accounting of how each of these elements of force posture evolved. Relative to nuclear weapons, which Chinese leader Mao Zedong once dismissed as “paper tigers,” given the perceived limitations of the credibility of nuclear threats, precision strike, counterspace, and cyberspace capabilities are regarded as more usable, flexible, and credible. As such, these capabilities can provide the “coercive leverage” that China seeks, while allowing for tight control of the risks of escalation. Cunningham defines the posture that follows from this capability development as one of “calibrated escalation” that provides a range of options along a ladder up to but still “under the nuclear shadow.”
Ultimately, these capabilities, which might be characterized as a new triad complementing the fully nuclear triad that China has been developing in parallel, can be regarded as instruments of an overall system of strategic deterrence that is extending increasingly beyond China’s nuclear arsenal to incorporate new concepts of information deterrence, as well as cyber and space deterrence. Pursuant to the increased importance of new domains and emerging capabilities, from artificial intelligence to deep sea developments, the factors that may influence deterrence are increasingly complex and multifaceted.
While Cunningham looks back to the 1990s for moments with catalytic impacts on China’s force posture, more recent noteworthy events may be relevant in anticipating future developments. For instance, the episode in 2020 when Chairman of the Joint Chiefs of Staff Gen. Mark Milley reached out to his counterpart in the PLA Joint Staff Department to assure that the U.S. military did not intend to attack China imminently, may be regarded as another incident with catalytic effects, while reflecting additionally a certain degree of misperception.2 The PLA’s response to House Speaker Nancy Pelosi’s visit to Taiwan in August 2022 also may have proven a moment that demonstrated a proof of concept for applying military power in a retaliatory manner and for the exercise of pressure, a trend that has become more prominent in the years since then.
This force posture and strategic outlook possess certain limitations. For China, the use of such information-age capabilities in signaling for coercive or deterrent purposes is inherently challenging. Among the mechanisms that Chinese military strategists anticipate using are deliberate disclosures, as by testing and demonstrations that publicly showcase such capabilities. The risks of entanglement in the underlying command systems and the dependencies between these domains create complexities, which may complicate the carefully modulated approach to escalation that Chinese leaders envision enacting. In particular, the increasing nuclear-conventional entanglement that has become a troubling feature of China’s overall posture has raised concerns about risks of escalation.3
Beijing’s capacity to convey the intentions behind certain activities and to influence potential adversaries’ perceptions of these capabilities constitutes another difficulty where there is significant potential for misperception. For instance, although the book mentions Volt Typhoon in passing, this is an episode that merits more detailed examination and consideration as an illustration of China’s approach. In particular, the reported pre-positioning of malware in U.S. and allied critical systems and infrastructure appears to highlight the realization operationally of certain concepts that Chinese military writers had long discussed conceptually.4 Such peacetime operations are also consistent with a view of the cyber domain that regards a blurring of boundaries between peace and warfare, as well as the inherent interrelatedness of reconnaissance and offensive operations, as features of this new space of conflict.
In that particular episode, even more curious was the apparent acknowledgment by Chinese officials of responsibility for these attacks and their statements to reportedly surprised U.S. counterparts that the purpose behind this operation was to respond to U.S. support and assistance for Taiwan.5 Unspecified in public reporting is whether that activity should be regarded as a punitive, coercive, or deterrent measure. Absent such explicit conveying of intentions, the intent behind cyber operations can be easily misconstrued; when the boundary between preparation for and imminent conduct of offensive operation is inherently uncertain from a technical perspective, presence on sensitive systems and networks, especially in a moment of crisis, could be taken as an indication of aggressive intentions, rather than a deterrent measure.
Questions of Command
Among the notable avenues for future inquiry is how China’s approach to command and control influences its capacity to leverage these information-age capabilities. Cunningham traces the evolution of PLA command of cyberspace capabilities from an earlier more freewheeling environment to increasingly centralized control, which prompted creation of the Strategic Support Force and later the PLA Cyberspace Force. The inherent question is whether Chinese leaders can achieve the desired strategic effects while limiting the delegation of control over strategic capabilities when the Chinese Communist Party prefers to maintain more centralized control.
To date, China’s capacity for coordination appears limited. Cunningham notes that there is little evidence of a structure to coordinate actions associated with strategic deterrence. Although there is almost certain to remain a high degree of opacity associated with these processes, the Central Military Commission’s Joint Operations Command Center presents a feasible mechanism for such coordination. The reported construction of a new potential wartime command center in Beijing, seemingly buried deep enough underground to withstand a nuclear attack, highlights the apparent intensity of concerns driving these developments.6 Meanwhile, Chinese political leaders may recognize the necessity of more delegated mechanisms of command in certain domains and for certain missions that place greater premium on the exercise of initiative.
The Nuclear Posture Puzzle
Among the inherent challenges associated with such a book is the dynamism of the topic. Under the Nuclear Shadow has been published against the backdrop of an active debate on the dramatic expansion of China’s nuclear arsenal. At first glance, the extent of China’s investment in modernizing, diversifying, and expanding its nuclear forces—which the U.S. Defense Department’s 2024 “China Military Power” report predicts will probably continue over the next decade7—would appear to contradict some of the premises in Under the Nuclear Shadow. Cunningham concentrates on the drivers for China’s development of non-nuclear strategic capabilities to substitute for nuclear threats. Yet the logic underlying these developments parallels that of strategic substitution, insofar as the PLA’s pursuit of more diversified nuclear capabilities allows greater optionality.
In this regard, the trend overall has been to expand options within and along the nuclear section of the escalation ladder. This drive for nuclear overmatch and escalation dominance appears to reflect a juxtaposition of a degree of insecurity, including in the context of U.S. missile defense capabilities, and the extent of China’s military ambitions, with the drive to become a world-class military by midcentury.
To some extent, there may be certain tensions or tradeoffs from a resourcing perspective between the logics of strategic substitution and the pursuit of nuclear overmatch. In parallel, there are indications that the PLA is increasing the readiness of its nuclear forces with a focus on rapid response, which shifts closer to a launch on warning posture. While there are reasons to hope that an approach of calibrated escalation, such as Cunningham characterizes China’s approach, will prevail, grounds for concern also arise about the apparent confidence of Chinese leadership that escalation can be controlled, especially given the potential for mistakes in signaling or misperception.
Author’s Contributions
Overall, Cunningham’s research provides important theoretical contributions to understanding Chinese military power. Her characterization of China’s force posture as one of calibrated escalation also possesses utility and value in projecting how Beijing might employ these capabilities for coercion in conflict. The theoretical framework of strategic substitution accounts for the logic of China’s bets on information-age capabilities as an attempt to offset U.S. military advantages.8 This drive for leverage centered on achieving quick, credible capabilities within a shorter time for the three elements of force posture is worth noting. However, in parallel, Chinese military modernization has pursued capabilities with longer timelines for development.
Perhaps the most fundamental consideration raised by this book is how to project the future trajectory of Chinese military power. The author articulates three plausible scenarios for China’s force posture: continuation of strategic substitution, change to a nuclear-first-use posture, or pursuit of conventional victory. These options appear far from mutually exclusive. At present, China appears to be pursuing a combination of the three trajectories, as reflected in continued development of information-age capabilities juxtaposed with dramatic expansion of its nuclear posture—albeit without a clear change to its position on nuclear first use—and significant expansion of conventional capabilities. If Chinese leaders start to face resource constraints because of economic headwinds, the telling sign may be how resources are prioritized and allocated among these different categories of capabilities.
This framework of strategic substitution provides a useful approach that has potential applicability to both nuclear and non-nuclear states. At a time when U.S. security guarantees and extended deterrence commitments are starting to be called into question, there are rationales for some U.S. allies and partners to pursue more sources of leverage and independent capabilities. For instance, Taiwan is pursuing new asymmetric capabilities through foreign military sales and domestic procurement, such as precision strike missiles, including coastal defense cruise missiles, and a growing number of unmanned systems.9 Relative to when China initially embarked on a quest to develop information-age capabilities, its tendency today toward commercial developments may make these strategies and the development of comparable capabilities more accessible to a greater range of states.
Ultimately, this work raises critical questions as the Chinese military looks to the future of power and warfare. Implicit in the theory of strategic substitution is how Chinese political and military leaders make decisions about the bets they place on technologies under conditions of uncertainty. To no small extent, China’s pursuit of information capabilities also occurred against the backdrop of concepts of a revolution in military affairs, the notion of a dramatic transformation that centers on the decisive impacts of information in warfare. These ideational influences have shaped decision-making on which technologies to pursue and prioritize.
Among the potential avenues for future research are how China’s drive for military innovation, which is producing new, yet untested capabilities, might be integrated into its overall force posture. Beyond the information-age capabilities that Cunningham characterizes as critical to deterrence, Chinese military strategists also are starting to explore the impacts of unmanned systems, military applications of artificial intelligence, and biotechnology developments, along with other emerging technologies, as new frontiers of military struggle and confrontation that could reshape future deterrence.10 In particular, the development of unmanned systems and artificial intelligence promise new near-term pathways for coercive leverage, and unmanned systems, particularly, are already starting to be applied in pressure operations targeting U.S. and Taiwanese decision-making. In this regard, these trends and themes will likely remain the subject of active debate with significant implications for the Indo-Pacific region and the global military balance.
ENDNOTES
1. There is also the question of how strategic substitution as a concept relates to other concepts prominent in Chinese writings, such as the notion of “asymmetrically counterbalancing” (非寇聳制衡) powerful adversaries that the Science of Strategy highlights. These information-age and other disruptive capabilities can also be characterized as shashoujian (杀手恝), or “assassin’s mace” capabilities in more popular parlance.
2. Phil Stewart and Patricia Zengerle, “Under fierce Republican attack, U.S. General Milley defends calls with China,” Reuters, September 28, 2021.
3. David C. Logan, “Are They Reading Schelling in Beijing? The Dimensions, Drivers, and Risks of Nuclear-Conventional Entanglement in China.” Journal of Strategic Studies 46, no. 1 (2023): p. 5-55. Henrik Stålhane Hiim, M. Taylor Fravel, and Magnus Langset Trøan. “The Dynamics of an Entangled Security Dilemma: China’s Changing Nuclear Posture.” International Security 47, no. 4 (2023):
p. 147-187.
4. See the initial reporting from Microsoft threat researchers on this activity, among other public sources: https://www.microsoft.com/en-us/security/blog/2023/05/24/volt-typhoon-targets-us-critical-infrastructure-with-living-off-the-land-techniques/
5. Dustin Volz, “In Secret Meeting, China Acknowledged Role in U.S. Infrastructure Hacks,” Wall Street Journal, April 10, 2025.
6. Demetri Sevastopulo, Joe Leahy, Ryan McMorrow, Kathrin Hille, and Chris Cook, “China builds huge new wartime military command centre in Beijing,” Financial Times, January 30, 2025.
7. For further context, see :U.S. Department of Defense, “Military and Security Developments Involving the People’s Republic of China,” December 2024.
8. Looking at the vernacular of U.S. defense debates, the question can also arise as to whether characterizing China’s approach to force development as an “offset strategy” would be appropriate. See, for instance: Timothy Walton, “Securing the Third Offset Strategy,” Joint Force Quarterly 82 (2016): p. 6-15.
9. See for instance: Justin Ling, “Taiwan Is Rushing to Make Its Own Drones Before It’s Too Late,” Wired, June 23, 2025.
10. See the PLA National Defense University’s 2020 edition of Science of Military Strategy (斑略偯) for further context.
Elsa B. Kania is a PhD candidate in Harvard University’s Department of Government and an adjunct senior fellow with the Technology and National Security Program at the Center for a New American Security.