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Report

August 16, 2023

The United States and its allies must be ready to deter a two-front war and nuclear attacks in East Asia

By Markus Garlauskas

Introduction

“If hostilities were to renew on the [Korean Peninsula] it is not a matter of ‘if’ the Chinese Communist Party will intervene, it is when … This has been a very difficult topic for us to address as an alliance.”— Retired Gen. Robert Abrams, former commander of US Forces Korea (USFK)¹Robert Abrams, panel discussion moderated by Markus Garlauskas, “Veteran Commanders and Diplomats Forum,” KDVA Reunion and ROK-US Alliance Peace Conference, Washington, DC, July 27, 2022, 4:17:38, https://www.youtube.com/watch?v=ztategs1rxM&t=15458s.

“I’ve wargamed conflicts with China and with North Korea dozens of times. If we look at a map and consider the forces involved, it is almost impossible for either to occur without some form of simultaneity.”—US defense official, name withheld

“If the political survival of Xi Jinping or Kim Jong Un is at stake in [a] military conflict they are losing, escalating to a limited nuclear strike would be rational … hesitating to use nuclear weapons would be the irrational act.”—US intelligence official, name withheld

The challenges to deterrence in East Asia have begun to change fundamentally in recent years, putting them on track to present grave risks to US national security interests over the coming decade. This report summarizes the results of a study focused on two of these emerging and interrelated challenges to deterrence in East Asia. The first is the potential for a conflict with either the People’s Republic of China (PRC) or North Korea to escalate horizontally and become a simultaneous conflict with both. The other is the possibility that either or both adversaries would choose to escalate vertically to a limited nuclear attack—rather than concede defeat—in a major conflict. 

US thinking about war in East Asia often neglects the possibility that the United States would have to fight the PRC and North Korea simultaneously rather than separately. Furthermore, conventional wisdom in the United States underestimates the risk that either the PRC or North Korea would resort to a limited nuclear strike in the event of a conflict in the region. However, the recent behavior of the United States’ adversaries in East Asia suggests that this thinking may be off the mark; the PRC military has reorganized itself to prepare to fight a two-front war, while both the PRC and North Korea continue to develop the sophistication and size of their tactical nuclear arsenals.

To better understand the threats posed by these two major risks five to ten years from now (in the 2027-2032 timeframe), we conducted a series of workshops and interviews with key government personnel and experts, and analyzed our findings in this report, originally written for the US Defense Threat Reduction Agency (but not necessarily representing its views). These findings should serve as a wake-up call: The United States and its allies can no longer think about conflicts with the PRC and North Korea in isolation from each other, and they must take urgent action to prepare for the possibility of facing limited nuclear attacks in an East Asia conflict scenario.

Key findings 

If a conflict with one adversary in East Asia doesn’t end quickly, expect it to widen. If a conflict is initiated by either the PRC or North Korea, the potential for expansion to simultaneous conflicts with both would pose a high risk to US and allied defense objectives, particularly because this would impose severe operational and strategic challenges. During this study, we found many plausible pathways from which a conflict with one could expand into conflicts with both, even without Beijing and Pyongyang coordinating with one another. Though it is ill-advised to confidently predict the flow of a conflict up to a decade from now, such pathways are sufficiently numerous and plausible that—if a conflict with either the PRC or North Korea does not conclude quickly—we should anticipate that simultaneous conflicts with both could result. 

• Deep distrust currently exists between the PRC and North Korea, and we found that neither is likely to feel compelled by any obligation to fight alongside the other—but this would not prevent the emergence of simultaneous conflicts with both. Advance coordination between the two is one of the less likely ways such simultaneous conflicts could emerge. We identified a series of far more plausible pathways, depicted in Figures 1 and 2.
• Simultaneous conflicts impose challenges so severe that the risk should still be considered high, even if the probability of these two conflicts occurring simultaneously is uncertain. The logistical challenges alone are daunting, given the requirements of such major conflicts, including stocks of precision standoff munitions and missile-defense interceptors. Operationally, simultaneous conflicts would force overstretched US command-and-control (C2) systems to make hard choices about how to allocate limited numbers of their most valuable assets. Meanwhile, alliance management and escalation management would become exponentially more complex.
• If North Korean aggression triggers a successful counteroffensive by the US and South Korea, this will likely prompt the PRC to intervene to protect its interests as North Korea collapses. Such intervention would likely spark a confrontation in the context of US-PRC rivalry and distrust, which could escalate to military conflict. Further, Beijing would likely be willing to risk a conflict to prevent Seoul and Washington from dictating the terms of Korean unification via an unchecked counteroffensive.
• Any major US-PRC conflict—for example, if the PRC attacks Taiwan—is likely to escalate horizontally and engulf Korea, unless the US-PRC conflict is a limited war with a quick, decisive outcome. In such a conflict, Beijing is likely to strike US regional bases, possibly including US Forces Korea (USFK) bases well within mutual striking distance of the PRC mainland. Even if the South Korean military and USFK are initially fenced off from hostilities, either side could view them as a US tool to break a stalemate or be drawn in as the PRC attacks US bases in Japan by overflying Korea. Additionally, Beijing could encourage Pyongyang to escalate in order to tie down US and ROK forces. Whether or not Beijing does, a US-PRC conflict would disturb North Korea’s escalation calculus. US reinforcements flowing to the region, along with US commitments and losses, could prompt opportunistic or preemptive aggression from North Korea—particularly because the conflict’s outcome would have immense implications for Pyongyang.
• A second conflict need not even escalate very far for such challenges to come into play. As a major conflict with the PRC or North Korea begins, the potential for escalation to draw in the other immediately affects the political and military options available to the United States and its allies, even if war is averted. Seoul’s efforts to avoid being dragged into a US-PRC war, for example, could constrain US forces in South Korea. Meanwhile, US and South Korean efforts to avoid a war with the PRC could hamstring US-South Korean operations in the Yellow Sea, or in mountainous areas near the PRC-North Korean border.

The risk that a war in East Asia would go nuclear is rising, as the PRC and North Korea have increasing incentive and capabilities for limited nuclear attacks. The risk of a limited nuclear attack by the PRC or North Korea in the event of conflict is likely to grow through the 2027–2032 time frame, and simultaneous conflicts would exacerbate this risk. Building on the results of another study we conducted but have not made public, “Preventing Strategic Deterrence Failure on the Korean Peninsula,” this study found that North Korea has been rapidly advancing its capability and intent to initiate a limited nuclear attack in the event of conflict.²Garlauskas, Preventing Strategic Deterrence Failure on the Korean Peninsula.  Though the study did not find evidence as compelling to show that the PRC is currently moving aggressively in this direction, it found evidence that the PRC’s capability to employ nuclear weapons for operational and tactical purposes is increasing.

• North Korean weapons capabilities and policy have moved rapidly toward enabling limited nuclear attacks. Pyongyang’s September 8, 2022, nuclear policy declaration set the stage and justification for limited nuclear attacks, stating that nuclear first use is an option to retake the initiative in a conflict, for example.³Ibid. Meanwhile, since January 2021, North Korea has been sounding a drumbeat on its tactical nuclear capabilities, including tests of claimed tactical nuclear-capable missiles and displays of a new tactical nuclear warhead.⁴Uri Friedman, “A Third Nuclear Age is Upon Us,” Atlantic, August 2, 2022, https://www.theatlantic.com/ideas/archive/2022/08/north-korea-kim-jong-un-third-nuclear-weapon-age/670993; “North Korea Confirms a Simulated Use of Nukes to ‘Wipe Out’ Its Enemies,” National Public Radio, October 10, 2022, https://www.npr.org/2022/10/10/1127796517/north-korea-confirms-a-simulated-use-of-nukes-to-wipe-out-its-enemies. ⁵Tianran Xu, “Size Estimates of DPRK’s Nuclear Devices,” Open Nuclear Network, June 29, 2023, https://opennuclear.org/publication/size-estimates-dprks-nuclear-devices.
• Though Beijing may not be matching Pyongyang’s focus on tactical nuclear options, PRC capabilities suited to limited nuclear attack—such as the DF-26 ballistic missile, dubbed the “carrier killer” or “Guam killer”—are already significant and on track to increase.⁶Austin Long, “Myths or Moving Targets? Continuity and Change in China’s Nuclear Forces,” War on the Rocks, December 4, 2020, https://warontherocks.com/2020/12/myths-or-moving-targets-continuity-and-change-in-chinas-nuclear-forces/ Though North Korea seems more likely than the PRC to initiate a limited nuclear attack, a North Korean nuclear attack would also raise the risk of a US-PRC nuclear confrontation, particularly if Beijing perceives the US response as threatening. In addition, if a US-PRC conflict starting elsewhere “horizontally” escalates to Korea, and yet PRC victory remains elusive, a “vertical” escalation to limited nuclear attack may be the next logical step from Beijing’s perspective.⁷For context, see: Talmadge, “Would China Go Nuclear?” 50–92.
• A PRC military intervention in a Korean conflict would also add dangerous new variables to North Korea’s nuclear calculus. An intervention without the North Korean regime’s prompting or permission would be a clear threat to its survival, likely making a limited nuclear attack appear to be the “least bad” option. Conversely, a PRC intervention permitted by North Korea, designed to help protect the regime from the consequences of its escalation, might lead Pyongyang to expect US restraint in response to a limited nuclear attack because of Washington’s fear of triggering a US-PRC nuclear war.

The United States and its allies are not situated to fight a two-front limited nuclear war in East Asia; the PRC may be soon. US and allied capabilities, command-and-control arrangements, and posture (including forces, bases, and agreements with allies) are unsuited to prevent simultaneous conflict with the PRC and North Korea and/or a limited nuclear attack or provide robust military response options if they occur. 

• Based on the workshop discussions, the logistical, command and control, basing, and alliance policy considerations of the United States and its allies in the Indo-Pacific all appear designed around and suited for one fight or the other. They aren’t designed for simultaneous conflicts with the PRC and North Korea. Further, this design signals, perhaps unintentionally, that the United States and its key East Asian allies are not yet seriously considering, much less preparing for, simultaneous conflicts. The US-South Korean alliance, in particular, often appears to be avoiding even discussion of this politically sensitive, yet critical, topic.
• The United States and its allies have appeared reluctant in recent years to actively and openly prepare a response to limited tactical nuclear attack in East Asia, much less to prepare to fight a “limited” nuclear conflict. Statements such “a nuclear war cannot be won and must never be fought” and “there is no scenario in which the Kim regime could employ nuclear weapons and survive” may be unintentionally signaling that the United States is deliberately unprepared for such possibilities, and is instead counting on the implicit threat of all-out nuclear conflict resulting from a single nuclear strike as a deterrent.⁸Ibid.; “Joint Statement of the Leaders of the Five Nuclear-Weapon States on Preventing Nuclear War and Avoiding Arms Races,” White House, January 3, 2022, https://www.whitehouse.gov/briefing-room/statements-releases/2022/01/03/p5-statement-on-preventing-nuclear-war-and-avoiding-arms-races. Decisions and statements about posture and capabilities also signal a disinterest in preparing limited-nuclear-response options, with US officials publicly dismissing the idea of redeploying tactical nuclear weapons to the region.⁹William Gallo, “US Rules Out Redeploying Tactical Nukes to South Korea,” Voice of America, September 24, 2021, https://www.voanews.com/a/us-rules-out-redeploying-tactical-nukes-to-south-korea/6243767.html.
• If current trends continue, the PRC is likely to be far better prepared than the United States to fight on multiple fronts in East Asia and to conduct limited nuclear strikes. The apparent lack of preparedness of the United States and its allies to fight simultaneous conflicts with the PRC and North Korea and for a limited nuclear conflict increases the chances that Beijing or Pyongyang—if already in conflict with the United States—would see advantage in moving first to expand to a dual conflict or escalate to a limited nuclear attack. The PRC’s establishment of a separate Northern Theater Command for Korea contingencies and the Eastern Theater Command for Taiwan contingencies, along with the fielding of accurate dual-capable missiles (nuclear and conventional) shows Beijing’s progress in this direction.

If conflict breaks out, however, the United States has options to manage escalation. The study found that, even if the United States fails to deter aggression by either the PRC or North Korea, there will still be key opportunities for integrated deterrence approaches to help reduce the risk of escalation to conflicts with both, or to a limited nuclear attack. The study identified a range of leverage points in Beijing and Pyongyang’s decision-making that could help to limit such “horizontal” and “vertical” escalation.

• Beijing’s view: Beijing probably wants to limit conflict and avoid a regional or nuclear war if it is employing force to achieve goals regarding Taiwan or maritime disputes, or if it is intervening to protect its interests in a Korea conflict. Workshop participants noted likely concerns in Beijing about the potential for uncontrolled escalation in such scenarios, and one expert particularly highlighted that Beijing’s “nightmare scenario” could be fighting the United States, Japan, and South Korea simultaneously. Given the difficulty that Beijing has had in influencing or constraining Pyongyang under more stable circumstances, PRC leaders are likely to believe that expanding a US-PRC war to the Korean peninsula would introduce new, uncontrolled, and unpredictable elements and complicate conflict termination. Similarly, Beijing likely recognizes that a military intervention during a North Korean conflict with South Korea and the United States holds many risks and uncertainties, including unpredictable effects on Pyongyang’s escalation calculus.
• Pyongyang’s view: Though North Korea is likely to see both opportunities and threats in the event of a US-PRC conflict, it almost certainly would be initially hesitant to embark on a level of aggression risking regime-ending consequences. Pyongyang would likely be skeptical of Beijing’s willingness to prioritize defending North Korea, even as “co-belligerents” fighting the United States and its allies simultaneously. North Korea would also likely be uncertain as to whether the United States or the PRC would be able to win a decisive victory, regardless of North Korean involvement. Though it may not be possible to deter some posturing or limited aggression by North Korea in such scenarios, there would be an opportunity to raise Pyongyang’s level of caution through integrated deterrence approaches.
• Personnel below the regime leaders’ level in both states could be susceptible to influence to delay or discourage escalation in such scenarios. Their personal interests may sharply diverge from those of their leaders in such extreme circumstances, as the risks of conflict escalation take precedence over fear of punishment for passivity or disobedience. The US and its allies could exploit the tendency of high-level officials in autocratic systems toward delay and confirmation, rather than prompt action.

Biases in US and allied institutions are impeding their understanding of how an East Asian conflict could escalate, and their preparations to manage such escalation. Deep-seated organizational and cognitive biases have obstructed the ability of the United States and its allies to anticipate, deter, and prepare for these two possibilities: simultaneous conflicts with the PRC and North Korea, or limited nuclear attack by either adversary. During the study, members of the research team and many of the expert participants found that such biases have often led to unfounded optimistic assertions, particularly the idea that Beijing or Pyongyang would remain a passive observer while the other fights a conflict that would have profound consequences for the security of both. (For more on the biases at work in the way the United States and its allies think about East Asian security, see Jonathan Corrado’s essay, “Biases blind us to the risk of Chinese military intervention in Korea.”)

• A bias toward overcentralized perception of adversary decision-making has obstructed US consideration of simultaneous conflicts with the PRC and North Korea. Many US personnel who have not closely studied the Pyongyang-Beijing relationship make unsupported assumptions about either the level of coordination between Beijing and Pyongyang or North Korea’s level of responsiveness to PRC direction—driving another assumption, that simultaneous conflicts would only happen by Beijing’s conscious choice. Others assume that the low trust between Beijing and Pyongyang made simultaneous conflicts impossible.
• Mirror imaging and wishful thinking were also common US and allied biases reported by study participants. In particular, some participants reported the widespread belief that the United States and the PRC have a common overriding interest in avoiding a two-front war or nuclear escalation, without considering whether this would hold true if the PRC were losing a war with the United States. Similarly, a frequent response to the idea of a limited North Korean nuclear attack is that North Korea “wouldn’t dare” to use nuclear weapons because its leaders “know it would be the end of their regime,” without considering scenarios in which the regime is already facing imminent destruction.
• What’s known as the “law of the instrument bias” was often identified during the study, as each of the three most relevant US four-star joint commands for these issues has a distinct and separate role. Deterring nuclear attack is the domain of US Strategic Command; deterring PRC aggression is the domain of US Indo-Pacific Command; and North Korean aggression is the domain of Combined Forces Command/US Forces Korea. This makes it difficult, but important, to enable integration across these commands in order to best address security challenges in East Asia. Integration will increase the range of resources available to each command and will thus help commands to view problems from new angles, rather than with a disproportionate focus on their own command’s regional or strategic domain.

How could simultaneous conflicts break out? 

Considered separately, the risks to US interests posed by simultaneous conflicts and limited nuclear attacks in East Asia are complex and daunting. Considering them together introduces further complexity. Given the relatively low potential for either the PRC or North Korea to begin aggression with a nuclear attack at the outset of a conflict, this analysis first establishes the potential pathways to simultaneous conflicts with the PRC and North Korea, along with the general scenarios that might result. It then establishes some of the driving and restraining factors for a limited-nuclear-attack decision, and from these derives a summary of conditions wherein simultaneous conflicts would be most likely to place the greatest strain on the potential for limited nuclear attack.   

The study found numerous plausible pathways from which aggression by either the PRC or North Korea could result in simultaneous conflicts with the United States in the coming decade, some of which are more likely than others. The study also found some pathways to be implausible. For example, it found that the prospects for a truly “collaborative” decision between Beijing and Pyongyang to initiate joint aggression are remote, even if one assumes that PRC-North Korea relations will have improved a decade from now. Therefore, the following analysis assumes that either Beijing or Pyongyang would be the “first mover” initiating the planning and preparations for such aggression, even in the unlikely scenario that PRC-North Korea relations and trust have improved to the point that some degree of joint planning and preparations take place. 

The flow of a conflict initiated by the People’s Republic of China 

Beijing has a wide range of potential justifications and motivations for initiating aggression. The scenario that receives the most attention is the potential for a PRC offensive to bring Taiwan under its control, either through a massive amphibious invasion or a coercive campaign using some combination of threats, limited strikes, and isolation of the island. However, there are other plausible scenarios for PRC aggression, including disputes over territorial claims in the South China Sea and the Senkaku Islands. In all of these cases, however, the PRC’s goals appear limited, and the PRC almost certainly seeks—at least at the outset—to achieve a decisive victory without having to resort to nuclear strikes or escalate to a global war with the United States. This is likely to motivate the PRC to limit the geographic scope of its initial aggression, to at least some degree. As a result, the study considered it possible that the PRC could plausibly choose not to initially attack US bases in South Korea, even if it attacks US bases and forces located elsewhere—on Japanese territory, for example. (See Figure 4 for some geographic factors constraining such a PRC approach.) Figure 1 depicts a range of potential pathways for a conflict initiated with a PRC attack on Taiwan to escalate to include North Korea. 

The flow of a conflict initiated by North Korea

Pyongyang also has a wide range of possible reasons and incentives for initiating aggression, with its most likely target being South Korea (ROK). For the purposes of this study, a foundational assumption, based on assessments of Pyongyang’s mindset and calculus, is that North Korea’s aggression would be intended to result in a limited conflict—rather than an all-out war to absorb the ROK, which it almost certainly understands it could not win.¹⁰For more on the logic of limited NK escalation, see: Garlauskas, Preventing Strategic Deterrence Failure on the Korean Peninsula, 4, 7–8, 15. As a result, such a conflict is unlikely to begin with a nuclear attack. To make for a more manageable scope, the study also set aside scenarios of a US- or ROK-initiated “invasion” or intervention in a North Korean collapse. 

Figure 2 depicts pathways of how such a conflict could flow, including situations that could serve as triggering conditions for North Korea to conduct a limited nuclear attack. Though focused on the potential for simultaneous conflicts, this graphic also shows that PRC intervention is not necessarily inevitable, and that there is even the possibility of a cooperative US-PRC response. However, the study participants largely assessed such cooperation as unlikely in the context of the expected intensification of US-PRC rivalry in the coming decade. 

Will these conflicts go nuclear?

We have no historical record of limited nuclear attacks to inform analysis of what might lead to such an attack—unlike the long track record for nuclear threats, demonstrations, and coercion—so it is appropriate to limit expectations of how confident we can be in such assessments. Similarly, parsing statements on nuclear-weapons policy by Beijing or Pyongyang is likely to reveal more about their current intentions for nuclear signaling than the actual dynamics and calculus for a limited nuclear attack in a conflict up to a decade from now. The wording of Pyongyang’s September 2022 “Law on Policy of Nuclear Forces” establishes explicit justifications for first use of nuclear weapons by North Korea in various scenarios short of all-out nuclear war, but only alludes to the possibility of conducting limited nuclear attacks.¹¹“DPRK’s Law on Policy of Nuclear Forces Promulgated,” Naenara, September 9, 2022, https://kcnawatch.org/newstream/1662721725-307939464/dprk%E2%80%99s-law-on-policy-of-nuclear-forces-promulgated/. The PRC’s potential logic for a limited nuclear attack is even more opaque, given its ostensible “no first use” policy. Despite this current policy, some US scholars argue that Beijing could, in a future war, choose “limited nuclear escalation as a way to force an end to the conflict.”¹²Caitlin Talmadge, “Beijing’s Nuclear Option,” Foreign Affairs, April 16, 2020, https://www.foreignaffairs.com/articles/china/2018-10-15/beijings-nuclear-option.

Lacking concrete evidence of PRC or North Korean calculations for limited nuclear attacks, Figure 3 summarizes a set of potential variables that could either restrain or encourage the adversary considering a limited nuclear attack, modeling the logic of an authoritarian regime considering such options.¹³This hypothetical logic is informed by a number of the study’s references, but particularly by: John Warden, “Limited Nuclear War: The 21st Century Challenge for the United States,” Livermore Papers on Global Security 4 (2018), https://cgsr.llnl.gov/content/assets/docs/CGSR_LP4-FINAL.pdf; and Shane Praiswater “Strategies of Limited Nuclear War with Modern Authoritarians,” in Sarah Minot Asrar, ed., On the Horizon: A Collection of Papers from the Next Generation (Washington, DC: Center for Strategic and International Studies, 2019), http://www.jstor.org/stable/resrep22545.16. These considerations are not a definitive “checklist,” but can provide analytic insight on the varying factors that are likely to come into play. 

The first and foundational set of variables to consider for this model is the state of the adversary’s leadership and its nuclear C2 system, including its perception of direct domestic and external threats to the leadership. This would set both the lens through which the adversary sees other variables and its ability to make and transmit a nuclear-use decision. Some damage to the nuclear C2 system—presuming it is not destroyed—is particularly likely to trigger nuclear strikes, which may not even be truly “limited.” For example, North Korea’s September 2022 policy warned that attacks on its nuclear C2 would automatically trigger a retaliatory nuclear response.¹⁴“DPRK’s Law on Policy of Nuclear Forces Promulgated.”

An additional set of variables expands to include operational considerations. If the capability to conduct such an attack is clear and tested, and a lucrative target for a limited nuclear attack is identified, this further incentivizes such an attack, particularly if the adversary sees it is facing a “a use or lose” window of time to execute it. 

A final set of variables adds the context of the broader strategic environment that could shape a decision. Though these broader strategic factors are unlikely to be decisive on their own in triggering a limited nuclear attack, these variables could help determine the final decision if the leadership and operational factors are tilting toward limited nuclear attack as an option. The study’s workshop discussions concluded that additional parties intervening against the adversary could be a particularly important factor in incentivizing a nuclear attack.   

Considering all the variables outlined above and depicted in Figure 3, the overall set of conditions most likely to prompt a limited adversary nuclear attack on US or allied targets in East Asia would be a case in which the adversary’s C2 and missile forces have come under attack, and it perceives it is losing. More specifically, if the PRC intervenes when North Korea is facing such conditions, but in a way that is not supportive of the North Korean regime, this intervention would make a North Korean limited nuclear attack even more likely. Such conditions would give the North Korean regime little reassurance of its survival without drastic measures, including a limited nuclear attack, while increasing its confidence that the United States would either respond to a limited nuclear attack forcefully, possibly stoking a US-PRC nuclear confrontation, or with restraint to avoid such a confrontation. Meanwhile, the strategic and operational context of such a conflict would incentivize quick escalation to limited nuclear attack as the best hope for leadership survival. 

Though it is difficult to assess the probability of a limited nuclear attack beyond its overall plausibility in the event of simultaneous conflicts in East Asia, we can be more confident in assessing the gravity of such an attack’s consequences. The near-immediate strategic and operational effects of even the smallest limited nuclear attack—including disrupting military operations, inflaming public opinion, and sharply increasing escalatory risks—would almost certainly far exceed its direct physical and tactical effects. Over the longer term, such a clear violation of the “nuclear taboo” and failure of nuclear deterrence would also mean that the consequences of a limited nuclear attack in East Asia could ripple globally and be felt for generations. 

What is it about East Asia that makes simultaneous conflicts more likely? Politics and geography. 

The geography of East Asia is a key potential variable increasing both the probability and impact of a US conflict with the PRC or North Korea expanding to simultaneous conflicts with both—particularly given the increasing ranges of modern sensors and weapons systems. Some examples of this are shown in Figure 4 below. 

Beijing could view USFK bases as threatening due to their proximity, even if USFK restrains its operations from these bases during a conflict. This is likely to become a greater concern for Beijing as US weapon and sensor ranges increase. From US bases in South Korea, the Army’s Precision Strike Missile (PrSM) would be able to strike portions of the PRC mainland, even the outskirts of Beijing and Shanghair, in the 2027–2032 timeframe (as depicted by the blue range radius). This is based on a US Army general’s publicly stated expectations for the extended range of this system in the next decade, which would be used as a primary weapon by US field artillery units.¹⁵Ken Kamper, “Fires Modernization,” Maneuver Warfighter Conference, Fort Benning, Georgia, February 15, 2022, 28:08, https://youtu.be/RuZxEbWV7s8?t=1689.

In a US-PRC conflict, even if the PRC refrains from striking US bases in South Korea, its ability to strike US bases in Japan would be constrained by the need to either avoid overflight of the Korean peninsula or risk provoking North or South Korea by flying missiles through their airspace (illustrated by Figure 4). Figure 4 also illustrates how much of a constraint for the PRC it would be to avoid overflight of the Korean peninsula and its nearby airspace if the PRC were attempting to effectively strike key US bases on the Japanese home islands as part of a US-PRC conflict. If the PRC were to employ its more numerous, and potentially more evasive, short-range ballistic missiles to overcome the missile defenses of these bases, this would require such overflights, as would medium-range missiles. The PRC could bypass Korea by employing aircraft, some cruise missiles, and intermediate-range missiles from eastern and southern China to strike these bases instead, but striking only in this way without attacks across the Korea peninsula would provide longer warning time and more favorable geometry for US and Japanese air and missile defenses of these bases.

Figure 4: Northeast Asian geographic considerations in a US-PRC conflict

How should the United States and allies prepare—intellectually and operationally?

Policy recommendations for key finding #1: If a US conflict with one adversary in East Asia doesn’t end quickly, expect it to widen. 

• The United States and its allies should re-conceptualize planning for aggression by either the PRC or North Korea as marking the start of an Indo-Pacific campaign that also requires deterring—and potentially defeating—the other possible adversary.  
• The United States and South Korea should shift their focus to a broader priority of protecting South Korea from aggression—encompassing deterrence of PRC aggression in addition to North Korean aggression.  
• The US government and non-government institutions should sponsor studies and wargaming on the potential conditions and drivers that might cause a US-PRC conflict over Taiwan to escalate to Korea. 

Policy recommendations for key finding #2: The risk that a war in East Asia would go nuclear is rising, as the PRC and North Korea have increasing incentives and capabilities for limited nuclear attacks.  

• The US defense community should direct and sponsor analysis and studies by the intelligence community and outside analytic entities to track and identify signposts of North Korea’s increasing capabilities and potential for limited first nuclear use, as well as signposts of the PRC potentially moving down this path.  
• In collaboration with its allies, the United States should refine and amplify declaratory policies to emphasize that the United States and its allies will not be divided by a limited nuclear attack. This should include contextualizing the US declaration that “there is no scenario in which the Kim [Jong-Un] regime could employ nuclear weapons and survive.¹⁶“2022 National Posture Review,” US Department of Defense, 2022, 12, https://media.defense.gov/2022/Oct/27/2003103845/-1/-1/1/2022-NATIONAL-DEFENSE-STRATEGY-NPR-MDR.PDF.
• In coordination with the United States’ East Asian allies and partners, US military planners should expand efforts to ensure preparedness to fight and win even if faced with limited nuclear attacks, and to clearly communicate this preparedness to adversaries and allies alike. To preserve a range of military response options other than nuclear retaliation, the stage must be set to avoid giving the impression that any response but an immediate nuclear counterattack would indicate weakness or hesitation.
• The United States should lead interagency efforts to explore and prepare options to respond to, mitigate risks of, and deter a limited nuclear attack by the PRC or North Korea—to include studies, workshops, and tabletops/wargames, at both unclassified and classified levels. This analysis should include evaluation of the pros and cons of a range of potential options to increase and signal readiness to employ US tactical nuclear weapons in response to a limited nuclear attack, if the situation calls for it—up to and including the potential ramifications of the reintroduction of US tactical nuclear weapons to the region or the Korean Peninsula itself.

Policy recommendations for key finding #3: The United States and its allies in the Indo-Pacific are not situated to fight a two-front limited nuclear war in East Asia; the PRC may be soon. 

• The United States should undertake a comprehensive reassessment of its C2 relationships and posture in East Asia in the context of evolving North Korean, PRC, and nuclear threats, to identify the appropriate C2 relationships in the event of simultaneous conflicts with North Korea and the PRC, as well as the best C2 arrangements for theater-level tactical nuclear responses, if needed.
• US defense and military planners should ensure that the United States has effective, timely, and credible options for its own limited nuclear strikes in response to a limited nuclear attack, in addition to robust non-nuclear options. Relevant nuclear capabilities should be resourced, trained, staffed, equipped, and supported, while enabling messaging to dispel any perception among adversaries and friends that there is a gap in US capability that could be exploited through a limited nuclear attack. 
• The United States defense community should expand its forward presence in South Korea and Japan, and its interactions with Taiwan, to help ensure that key US allies and partners are intellectually and operationally better prepared for a conflict with the PRC and/or North Korea that involves a limited nuclear attack by either or both.  

Policy recommendations for key finding #4: However, if conflict breaks out, the United States has options for managing escalation.

• Across an array of commands, the US military should undertake efforts to apply and operationalize a greater focus on integrated deterrence approaches for intra-conflict deterrence, rather than just deterrence of conflict in general. 
• The United States and its allies should seek more multilateral (such as including Australian, UK, or Canadian) rotational contributions of aircraft and maritime patrols, and involvement in exercises to reinforce international commitment and contributions to deterrence of both North Korean and PRC aggression. 
• The US government should pursue study, development, and execution of approaches to pursue “sub-regime deterrence” within the PRC and North Korea as part of US integrated deterrence strategy, including targeted influence of mid-level actors, to delay or prevent execution of escalatory moves, particularly limited nuclear attack. 

Policy recommendations for key finding #5: Biases in US and allied institutions are impeding their understanding of how an East Asian conflict could escalate and their preparations to manage such escalation.

• The United States and allied analysts should develop new assessments of the likelihood and potential indicators of simultaneous conflicts with the PRC and North Korea, as well as limited nuclear attack by Beijing or Pyongyang. These should use structured analytic techniques, like key-assumptions checks, to identify and overcome biases.
• US and allied leaders should establish guidance that the risks of simultaneous conflicts with the PRC and North Korea, and limited nuclear attack by either, have such key implications that they military planning and exercises should consider and address these possibilities, even if they are not used as the “baseline.”
• The United States and its allies should establish working groups that cut across a variety of military commands to address preparation for simultaneous conflicts and limited nuclear attacks.
• US policymakers and analysts should lead efforts to ensure their allied counterparts engage with the potential for simultaneous conflicts and adversary limited nuclear attacks through repeated inclusion of these possibilities in scenarios for exercises and dialogue agendas. 

Author biography and acknowledgments

Markus Garlauskas is the director of the new Indo-Pacific Security Initiative of the Scowcroft Center for Strategy and Security, which replaces the former Asia Security Initiative. He leads this new initiative’s efforts focused on security, prosperity, and freedom in the Indo-Pacific region. He led projects focused on deterrence and defense issues in East Asia as a nonresident senior fellow from August 2020 until assuming his duties as director in January 2023.

Garlauskas served in the US government for nearly twenty years. He was appointed to the Senior National Intelligence Service as the National Intelligence Officer (NIO) for North Korea on the National Intelligence Council from July 2014 to June 2020. As NIO, he led the US intelligence community’s strategic analysis on North Korea issues and expanded analytic outreach to non-government experts. He also provided direct analytic support to top-level policy deliberations, including the presidential transition, as well as the Singapore and Hanoi summits with North Korea.

Garlauskas served for nearly twelve years overseas at the headquarters of United Nations Command, Combined Forces Command and US Forces Korea in Seoul. His staff assignments there included chief of the Intelligence Estimates Branch and director of the Strategy Division. For his service in Korea, he received the Joint Civilian Distinguished Service Award, the highest civilian award from the Chairman of the Joint Chiefs of Staff.

Garlauskas holds a BA in History from Kent State University. He earned a master’s degree from Georgetown University’s Security Studies graduate program, where he is now an adjunct professor.

A version of this report was originally written for the U.S. Defense Threat Reduction Agency (DTRA), but it does not necessarily express the views of DTRA or any other US government organization. The principal investigator thanks DTRA, particularly the Strategic Trends team, for sponsorship, guidance, support, and resources for this study. Thanks also go to all the experts and stakeholders, inside and outside of government, who participated in the study’s program events and contributed their perspectives to enrich the analysis. Special appreciation goes to members of the staffs of USSTRATCOM, UNC/CFC/USFK, Air Force Futures, and the Defense Intelligence Agency for their willingness to repeatedly donate their limited time to inform this study with invaluable operational and strategic perspectives. 

The principal investigator would also like to thank Lauren Gilbert, Kyoko Imai, Emma Verges, and Katherine Yusko of the Indo-Pacific Security Initiative Team for their key supporting roles in this study and this final technical report, as well as contributors and project consultants Jonathan Corrado, Gregory Park, and a colleague who prefers to remain anonymous. Thanks also go to the Atlantic Council’s president and CEO Frederick Kempe, as well as Gretchen Ehle, Nicholas O’Connell, and Caroline Simpson, without whose support the resources for this study would not have been possible. Lastly, he would like to acknowledge acting Scowcroft Center Senior Director Matthew Kroenig and former Senior Director Barry Pavel for their leadership and support for this project. This report is intended to live up to their charge to meet Gen. Brent Scowcroft’s standard for rigorous, relevant, and nonpartisan analysis on national security issues. 

Key references

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Image: A Hwasong-18 intercontinental ballistic missile is launched from an undisclosed location in North Korea in this image released by North Korea's Korean Central News Agency on July 13, 2023. KCNA via REUTERS