[US-China Nuclear Competition Special Report] I. Theoretical Review of the Possibility of a US-China Nuclear Crisis

I. Current Status Analysis

Amidst deepening US-China conflict and competition, one of the most concerning issues is the rapid enhancement of China's nuclear capabilities and the resulting increase in instability. Since its successful development of nuclear weapons in the 1960s, China has maintained a relatively small number of nuclear weapons based on the so-called minimum deterrence strategy, aiming to possess only the minimum necessary nuclear capabilities for deterring adversaries. While Russia and the United States still possess over 5,000 nuclear warheads, China is estimated to possess approximately 350 (Federation of American Scientists 2022).

However, assessments suggest that China has begun to actively enhance its nuclear capabilities, moving beyond the minimum deterrence strategy. This phenomenon, known as 'vertical proliferation,' refers to nuclear-armed states enhancing their military nuclear capabilities quantitatively and qualitatively. Last year's annual report on China's military power by the U.S. Department of Defense estimated that China is rapidly increasing its stockpile of nuclear warheads, projecting it to possess 700 by 2027 and 1,000 by 2030. Furthermore, China has constructed hundreds of new ICBM silos in recent years. Given that it currently possesses around 100 ICBMs, this suggests that China plans to produce and deploy a significant number of new silo-based ICBMs in the future (Department of Defense 2021).

Alongside this quantitative growth, China's qualitative enhancement efforts to improve the survivability of its nuclear weapons in wartime are also accelerating. The recent construction of new hardened silos is a prime example of these efforts. With the deployment of Jin-class (Type 094) nuclear-powered submarines capable of operating nuclear-armed SLBMs, China has recently acquired, for the first time, submarine-based nuclear deterrence capabilities. Moreover, by significantly enhancing the payload capacity of its new H-6N bombers, enabling them to carry nuclear-armed ALBMs, China has begun to establish a rudimentary nuclear triad across land, sea, and air.

II. Review of US-China Nuclear Crisis Potential

Given China's rapid expansion of nuclear weapons, when and how could a nuclear crisis arise between the US and China? The simplest scenario to imagine is a preventive war initiated by the United States out of concern for China's growing nuclear capabilities. However, considering that the two countries are not in an overt military adversarial relationship that would justify all-out war, and that China possesses ICBMs capable of striking the US mainland, the likelihood of the US launching a preemptive strike solely to eliminate China's nuclear weapons is not high.

A more realistic scenario involves an accidental conflict in geopolitical flashpoints such as Taiwan, North Korea, or the South and East China Seas escalating into a nuclear war crisis, potentially after an all-out conventional war. Based on international relations theories of nuclear strategy and deterrence, this report examines the potential for crisis through two types of risks: short/medium-term and long-term.

1. Short/Medium-Term Risk: Potential for Accidental Nuclear Crisis due to China's Asymmetric Vulnerability

The first is the risk of an accidental nuclear war during the transitional period until China achieves quantitative and qualitative nuclear parity with the United States, a situation that could occur from the present until around 2030-2035, when China is projected to achieve a significant level of nuclear capability enhancement. China's rapid nuclear capability expansion has been most directly influenced by the deepening threat perception stemming from advancements in US military technology. The 'revolution in accuracy' driven by remarkable progress in electronic, mechanical, and aerospace engineering has enabled unprecedented advancements in missile accuracy, allowing both nuclear and conventional missiles to more effectively neutralize enemy nuclear weapons. Furthermore, advancements in long-range sensors and data transmission/processing technologies enhance the capability to effectively track and destroy dispersed and hidden nuclear weapons (Lieber and Press 2006; 2017). In addition, the US is actively investing in developing capabilities, known as 'left of launch,' such as cyber and electromagnetic attacks, to neutralize an adversary's nuclear command, control, and launch facilities before missile launch. The rapid development and military application of artificial intelligence (AI) technology are expected to enable enhanced capabilities for surveillance, reconnaissance, and attack on nuclear command and control facilities at levels previously unimaginable (Schmidt 2022). The aforementioned US military technological innovations threaten the foundation of the long-established formula of 'strategic stability following the establishment of Mutually Assured Destruction (MAD) between nuclear powers,' and notably, in this year's Nuclear Posture Review (NPR), the US declared 'integrated deterrence,' which combines newly enhanced conventional military capabilities with existing nuclear weapons, as the core strategy for overall nuclear deterrence and defense policy (Department of Defense 2022).

The problem is that China's rapid nuclear capability expansion in response is further accelerating these US efforts, creating a mutually reinforcing spiral between the two countries. Consequently, China will remain in a state of uncertain nuclear deterrence for a considerable period. This uncertainty could push the Chinese leadership into a 'use-it-or-lose-it' psychological trap during a low-intensity conventional military conflict between the US and China. This is because the Chinese leadership might perceive that, in response to US attacks during a conventional all-out war, the US is targeting not only China's conventional forces but also its nuclear capabilities. Even if the US has no such intention and is only targeting conventional weapons, the distrust between the US and China and the anxiety over asymmetric vulnerabilities could increase the possibility of a preemptive nuclear strike by China, driven by the thought that its nuclear assets could be lost if not used now (Talmadge 2017).

Of particular note in this regard is the issue of 'nuclear entanglement.' The dual-use delivery systems capable of carrying both nuclear and non-nuclear warheads, and the organizational integration and mixing of units operating nuclear weapons with those operating conventional forces, entangle nuclear weapons with conventional forces at the deployment and operational stages, thereby increasing the possibility of accidental nuclear war. Even if an adversary's intention is solely to attack conventional forces, the nuclear weapons entangled with them are also threatened, placing the nuclear-armed state in a 'use-it-or-lose-it' situation (Acton et al 2017). China is not immune to this problem; the People's Liberation Army Rocket Force, responsible for operating nuclear weapons, also manages a wide array of conventional missiles, and operates dual-use delivery systems like the DF-26 missile. In this context, if an accidental conflict escalates into an all-out conventional war and the US attempts to eliminate the conventional forces of the PLA Rocket Force, the Chinese leadership might perceive this as an attempt to eliminate its nuclear weapons and launch a preemptive nuclear strike against the US. Conversely, there is also the possibility that the US might misinterpret Chinese conventional missile launches during a conventional all-out war as nuclear missile launches, leading to an escalation into full-scale nuclear war.

2. Long-Term Risk: Potential for Nuclear Crisis After the Establishment of a Balance of Terror

Will the possibility of nuclear war between the US and China disappear once China achieves a certain level of nuclear balance with the US through its rapid nuclear capability expansion in the long term? Some optimists argue that once Mutually Assured Destruction (MAD) is established, there is little to worry about. This view is based on the premise that if both the defending and challenging states possess second-strike capability—the ability to retaliate with nuclear weapons after suffering a nuclear attack—then both sides will avoid not only nuclear war but also conventional conflicts that could escalate to nuclear war, due to the obvious consequence of MAD. According to this perspective, the illusion and miscalculation regarding victory through preemptive attack, which has been a major cause of past wars, have largely disappeared in the nuclear age. This 'nuclear revolution' has led to the absence of war between great powers, a strengthening of the status quo tendency, and a decrease in the frequency of international crises (Jervis 1989).

However, various empirical studies show results that differ from the predictions of the nuclear revolution theory (Harvey 1997, 22-32). Many studies have confirmed that a state's possession of nuclear weapons has not had a significant impact on the deterrence of conflict outbreak (George and Smoke 1974; Gartzke and Jo 2009), the escalation and intensification of conflicts (Geller 1990), and their outcomes (Huth and Russett 1984; Betts 1987; Huth and Russett 1988). Cases such as the Sino-Soviet border conflict (1969), the Yom Kippur War (1973), the Falklands War (1982), and the Kargil War (1999) also serve as counterexamples to the nuclear revolution theory. While the absence of direct armed conflict between the US and the Soviet Union during the Cold War remains a strong argument for the nuclear revolution theory, the fact that US policymakers did not abandon the option of air strikes to eliminate Soviet nuclear missiles during the Cuban Missile Crisis in 1962 demonstrates the vulnerability of the optimism presented by the nuclear revolution theory (Kim and Martn 2021).

If so, how could a crisis of full-scale nuclear war arise between the US and China despite a balance of mutual nuclear terror? The first possibility is a nuclear crisis caused by the 'escalate to de-escalate' strategy. The core idea of this strategy is to overcome conventional force disadvantages and terminate a conflict early by launching a limited nuclear attack at the outset of a conventional conflict. The US government and many experts warn that Russia has adopted this doctrine since the 2010s and may resort to preemptive nuclear use from the early stages of a military conflict with NATO (Department of Defense 2018; Kroenig 2018). This strategy is based on the optimism that even if a limited nuclear attack is carried out in a regional conflict, the other side will not resort to full-scale nuclear war due to the balance of mutual nuclear terror. If one side, either the US or China, attempts to opportunistically exploit the balance of terror with this optimistic outlook, early use of nuclear weapons could occur in conventional wars stemming from accidental conflicts in Taiwan, North Korea, or the South and East China Seas. However, the core premise of the 'escalate to de-escalate' strategy—that control and early termination of conflict through limited nuclear war are possible—is extremely dangerous and lacks empirical evidence. Once nuclear weapons are used, regardless of scale, the adversary may interpret it as a signal for full-scale nuclear war, and the possibility of conflict escalating into a massive nuclear war cannot be ruled out.

The second possibility is the risk of accidental nuclear war caused by the 'stability-instability paradox.' Numerous empirical studies suggest that between states in a balance of terror, the frequency and likelihood of low-intensity conflicts actually increase, a phenomenon known as the stability-instability paradox (Snyder 1965; Rauchhaus 2009). Like the 'escalate to de-escalate' strategy, the stability-instability paradox is also based on deterrence optimism. Its core lies in the behavioral logic of actors who, judging that the possibility of full-scale war has significantly decreased due to the establishment of a balance of terror, engage in more adventurous low-intensity military provocations and conflicts. China is already increasing the frequency and intensity of low-intensity provocations in the South and East China Seas, the Taiwan Strait, and other areas. This trend is expected to intensify once it achieves a balance of terror with the US through rapid enhancement of its nuclear capabilities. The problem is that low-intensity military provocations and conflicts always carry the risk of escalating into conventional all-out war, and ultimately, nuclear war (Jervis 1989). Thus, the logic of the stability-instability paradox suggests that the establishment of a balance of terror between the US and China, driven by China's nuclear capability enhancement, could significantly threaten the strategic stability of their relationship by increasing the frequency and likelihood of low-intensity conflicts that harbor the potential for escalation.

The third possibility is accidental nuclear crisis that could arise from the introduction of artificial intelligence (AI) technology into nuclear command and control systems (Schmidt 2022). Although no country has yet implemented automated control of AI for lethal weapons due to technical and ethical constraints, it is uncertain whether this will remain the case in 10 or 20 years, given the rapid advancement of AI technology and its military utility. Of particular concern in this regard is the application of AI to nuclear command and control systems. Theoretically, AI can enable rapid and accurate decision-making and weapon operation, and eliminate the possibility of human error, such as cognitive misperception or communication mistakes (Johnson 2019). The problem is that due to the data processing volume and speed that far exceed human cognitive capabilities, it is practically impossible to understand why and how AI reached a particular decision. Even if the final decision to use nuclear weapons rests with humans, policymakers might face a situation where they must make a decision to use nuclear weapons without fully understanding why and how a warning of imminent nuclear use by an adversary was issued by an AI-driven surveillance and reconnaissance system, in a rapidly unfolding crisis. A more serious issue is that even if the AI's data processing is internally flawless, errors can occur in algorithm design, machine learning, or data collection due to incorrect data input or intentional attacks/sabotage, leading to erroneous AI judgments (Fitzpatrick 2019). These possibilities suggest that the future introduction of AI technology into nuclear command and control systems could lead to accidental nuclear crises between the US and China.

III. Implications

The aforementioned scenarios of US-China nuclear war crises are hypothetical situations posited based on the logic of nuclear strategy theory. Considering the relatively stable mutual deterrence system between the two countries, and the conservative and cautious nuclear strategies and postures of their current leaderships, it is unlikely that these scenarios will materialize in the near future. However, given the accelerating pace of military technological development, the changing balance of nuclear and military power between the US and China, and above all, the rapidly deteriorating US-China relationship, it cannot be guaranteed that the US and China will remain indefinitely free from the risk of accidental nuclear war.

The analysis above suggests the need for cooperation and coordination between the US and China in the following areas. First, since all scenarios of nuclear war between the two countries originate from the accidental escalation of small-scale military conflicts in areas such as Taiwan, North Korea, or the South and East China Seas, cooperation and coordination between the US and China are necessary for their prevention. To this end, it is essential to first revitalize the crisis management mechanisms and related dialogues between the two countries, which have weakened since the Trump administration. In particular, by clearly communicating how each country perceives and establishes the 'firewall' between conventional and nuclear war, the risk of nuclear escalation due to misperception should be reduced.

Second, China should refrain from exacerbating the problem of nuclear entanglement and enhance communication with the US on this issue. Some US experts have recently suggested that China might intentionally exploit the issue of nuclear entanglement (Talmadge 2017; Panda 2020). They argue that by deploying and operating nuclear and conventional weapons together, or by developing and operating dual-use delivery systems, China can (1) create ambiguity about which missiles are nuclear during a nuclear crisis, thereby overcoming its asymmetric vulnerability against the US with a limited number of nuclear warheads, and (2) deter the US from attacking Chinese conventional forces during a conventional war by raising concerns about nuclear escalation. However, as this nuclear entanglement problem deepens, the US will be driven to secure overwhelming first-strike capabilities, accelerating the US-China nuclear arms race. Most importantly, the risk of escalation to accidental nuclear war will increase. To prevent this, China should refrain from intentionally exploiting nuclear entanglement in weapon system development and operation, and communicate with the US on this issue.

Third, the United States should also make efforts to alleviate China's anxiety and concerns regarding its asymmetric vulnerabilities related to nuclear weapons. China harbors deep anxiety about the recent qualitative advancements in US military technology that threaten the foundation of MAD. Confidence-building measures between the US and China are necessary to alleviate this anxiety. Resumption of public and private dialogues is needed to resolve distrust and enhance mutual understanding regarding the operational concepts, doctrines, and strategies of nuclear weapons, as well as surveillance, reconnaissance, and missile defense systems. Through these efforts, the possibility of accidental nuclear crises between the two countries can be reduced, and a bridgehead for the nuclear arms control negotiations with China, desired by the US, can be established. ■

References

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Fitzpatrick, Mark. 2019. “Artificial Intelligence and Nuclear Command and Control.” Survival 61, 3: 81-92.

Gartzke, Eric and Jo, Dong-joon. 2009. “Bargaining, Nuclear Proliferation, and Interstate Disputes.” Journal of Conflict Resolution 53, 2: 209-233.

Geller, Daniel S. 1990. “Nuclear Weapons, Deterrence, and Crisis Escalation.” Journal of Conflict Resolution 34, 2: 291-310.

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Kim, Yang Gyu and Flix E. Martn. 2021. “At the Brink of Nuclear War: Feasibility of Retaliation and the U.S. Policy Decisions During the 1962 Cuban Missile Crisis.” All Azimuth: A Journal of Foreign Policy and Peace 10, 2.

Kroenig, Matthew. 2018. A Strategy for Deterring Russian De-escalation Strikes. Washington, DC: The Atlantic Council.

Lieber, Keir A., and Daryl G. Press. 2006. “The End of MAD? The Nuclear Dimension of US Primacy.” International Security 30, 4: 7-44.

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■ Author: Lee Jeong-seok_Visiting Research Fellow, James Madison University. He holds a BA and MA in Diplomacy from Seoul National University and a PhD from Princeton University. His main research areas are international security, U.S. foreign policy, and East Asian international politics. He has previously served as a Visiting Fellow at the Reischauer Center for East Asian Studies at Johns Hopkins University SAIS and as a Postdoctoral Researcher at the Albritton Center for Grand Strategy at Texas A&M University. His major works include "South Korea's Aircraft Carrier Debate," "Comparative Analysis and Outlook of the Trump and Biden Administrations' Northeast Asia Policies," and "Advocates of Restraint Strategy: Research on the Production and Diffusion of the U.S. Foreign Policy Restraint Discourse through the Policy Advocate Theory (co-authored)." He has also co-authored chapters in books such as <Theories and Practices of National Security>.

■ Author: Kim Yang-gyu_He concurrently serves as the Director of the Secretariat (Senior Researcher) at the East Asia Institute and as a lecturer in the Department of Political Science and International Relations at Seoul National University. He received his BA in French Education and Diplomacy and his MA in Diplomacy from Seoul National University, and his PhD in International Politics from Florida International University. He previously served as an adjunct professor at Florida International University and as a visiting scholar at the Saltzman Institute of War and Peace Studies at Columbia University. His main research areas include coercive diplomacy, nuclear strategy, power transition, U.S.-China relations, the North Korean nuclear issue, and international politics and security theory.

■ Managed and Edited by: Park Han-soo_EAI Research Assistant

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