Editor's Note

EAI is publishing a special report series as part of its ongoing research into US-China competition and the role of middle powers like South Korea from a long-term perspective. In this final article of the series, which addresses military security issues between the US and China, Professor Jeon Jae-sung predicts that if military conflict ultimately materializes, the damages for both countries will be immense across all sectors, suggesting the possibility of avoiding military conflict and seeking reconciliation and adjustment after a short-term conflict.

I. Deepening US-China Strategic Competition for Hegemony and the Confrontation and Conflict Patterns in the Military and Security Sectors

The strategic competition between the United States and China is transforming into a hegemonic competition. The ongoing competition in economic, technological, and political/socio-cultural spheres is proceeding concurrently with competition in military and security sectors, potentially leading to military competition and conflict. It can be assumed that the US and China will mobilize all available military and security means against each other while economic, technological, and political competition unfolds, attempting to link military and other sectors to gain an advantage in the overall competition. What pressure/conflict cards can the US and China play against each other in the military domain? What damages would the US incur if such cards were played? What are the medium-term (2030-2040) and long-term (up to 2050) prospects?

The most certain card in the military domain is to pressure the opponent through victory in direct military conflict or war. Direct military conflict between the US and China is a scenario where both countries assume victory against the other based on their respective motivations. It is possible to assume a situation where one side, either the US or China, initiates the conflict. First, let's consider the case of a preemptive strike by the United States.

The US is projected to maintain an overall military advantage over China until 2050. Based on this superior military strength, if the US perceives itself to be at a disadvantage in other sectors and concludes that reversing the hegemonic competition with China is inevitable, it may resort to a preemptive strike using its military power. As competition between the US and China intensifies in economic, technological, and political spheres, and as conflicts in these areas become visible, increasing the possibility of China surpassing the US, the US will likely leverage its overwhelming military advantage to pursue a swift military conflict and preemptive subjugation to outpace China's advancements.

Conversely, China, being generally at a military disadvantage compared to the US, is unlikely to attack the US mainland, US bases and military assets in the Indo-Pacific, or US allies where a US counterattack is certain. However, China has clearly stated its intention to defend its core interests—such as national sovereignty, security, and continued economic development, as defined around 2010—using military force if attacked by the US. In such a scenario, China might seek to secure its interests by launching military attacks against the US. It is possible for China to plan a militarily advantageous conflict, achieve military victory against the US, and secure military accomplishments that can be presented as a victory, even if not achieving complete unification, through a short and high-intensity war, such as a preemptive strike on Taiwan. This is the most prominent example.

Beyond pressuring the opponent through direct military conflict to gain an advantage or achieve results in the hegemonic competition, another set of cards that can be played involves strengthening mutual military deterrence while pursuing the weakening of the opponent's national power through military competition and pressure. First is the pressure of increased military spending. Both the US and China can pressure each other's spending through continuous defense expenditures and weapons development. In the 1980s, the US pursued the Strategic Defense Initiative (SDI), triggering an excessive arms race and creating an opportunity to win the Cold War due to the Soviet Union's excessive military spending.

Second is the pressure exerted through the development of weapon systems and military strategies. The US is already developing advanced weapons based on concepts such as the Third Offset Strategy and Multidomain Operations (MDO) or Crossdomain Operations, and has proposed the Pacific Deterrence Initiative (PDI) to counter China. China, in response, is pursuing an Anti-Access, Area Denial (A2AD) strategy, developing various advanced weapons such as ground-based aircraft carrier-killer ballistic missiles and hypersonic glide weapons. Furthermore, the arms race between the US and China over various technologies of the Fourth Industrial Revolution is intensifying, suggesting that competition in military spending, military technology, and consequently military strategy will also serve as powerful cards against each other in the future.

Third is the pressure of securing allies. The bilateral security and military competition between the US and China could potentially expand into a full-scale competition for the Asian security architecture, alliances, and strategic partnership networks. Most Asian countries will be affected by the US-China security competition. To date, the US has been strengthening existing alliances and expanding cooperation with strategic partner countries within the framework of its Indo-Pacific Strategy. Conversely, China is expanding its network of countries along the Belt and Road Initiative and strengthening security and military cooperation with these nations. The expansion of these military spheres of influence is also being used as pressure tactics against each other, ultimately leading to competition that considers US-China military deterrence, and even military conflict.

In past cases of hegemonic competition, shifts in the balance of power, or power transitions, the so-called Thucydides Trap, most instances involved armed conflict, but not all.[1]There are also cases where victory or defeat in other domains was decided before military conflict between the two countries, or where power transitions occurred peacefully without armed conflict. To achieve this, it is necessary to share an accurate assessment of each other's military capabilities, establish mechanisms for resolving disputes that can address conflicts on a case-by-case basis, and lower expectations regarding what can be gained through war. The competition between the US and China also requires a clear assessment of each other's military capabilities, an understanding of their respective conflict factors, and a moderation of expectations regarding the use of military force.

Table) Future Military Balance, Conflict Prospects, and Damage Estimates between the US and China

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II. Future Development of Competition in Military Spending, Capabilities, and Strategy, and the Pressure Tactics of Both Countries

1. Competition between the US and China over Future Military Spending

Both the US and China are strengthening their pressure tactics by continuously increasing their defense budgets. To date, the US maintains its military spending globally, has a significant gap in defense budgets compared to China, and leads China considerably in military technology. The fundamental assumption for projecting future defense budgets is to rely on data regarding the GDP trends of the US and China. While various methods have been used to calculate defense budgets, the approach of calculating the amount of defense spending as a percentage of GDP is considered most suitable for long-term trends.

In China's case, although defense spending has fluctuated between 7% and 12% annually, it has generally remained at a level similar to its economic growth rate. Therefore, future defense spending can be projected by assuming a similar rate of increase for both economic growth and defense spending. Despite the economic growth rate experiencing fluctuations for about two years due to the COVID-19 pandemic, it is expected that the economic slowdown in 2020 can be offset after the widespread availability of vaccines in 2021. Thus, the long-term trend up to 2050 can be considered within the context of the trend since the beginning of the 21st century.

Accuracy issues may arise in calculating China's defense spending.[2] It was later revealed that the Soviet Union spent approximately twice as much on defense as estimated by experts within the US Department of Defense, which significantly impacted the weakening of the Soviet economy.

However, in China's case, it can be seen that considerable data is available regarding China's GDP, budget, and defense spending. China publishes a defense white paper every two years, providing defense spending figures and information on its military capabilities. The issue is not with the calculation of the amount but with the items included in the defense budget. China does not include research and development costs, nor the budgets for police forces and militias outside the military, which is indeed a problem in accurately assessing China's military expenditure.

However, it is difficult to argue that China's military spending is so inaccurately calculated as to lead to a misunderstanding of its impact on China's economic development, similar to the Soviet Union's case. Above all, China has learned from the immense economic burden and historical consequences that the US-Soviet arms race imposed on the Soviet Union in the 1980s. Therefore, it tends to refrain from excessive spending due to an arms race and from uncritically responding to US policies that provoke an arms race. While recalculating China's self-reported military spending to align with Western standards may result in slight differences, these are unlikely to be significant enough to distort the military gap between the US and China.

It is true that US defense spending has been dispersed not only in Asia but also in the Middle East, counter-terrorism strategies, and Europe. However, since the Obama administration, the importance of Asia has been recognized, leading to the adoption of an Asia-pivot strategy, and it was announced that 60% of the US's total naval power would be concentrated in Asia. This trend is expected to expand further in the future. The US has withdrawn entirely from the Middle East, is minimizing expenditures for counter-terrorism, refraining from intervention in Europe, and pursuing policies to encourage European allies to support the Indo-Pacific. It is reasonable to assume that most of the military spending by the US from the 2020s onwards is directed towards the Indo-Pacific region with China in mind.

Figure) US Defense Spending as a Percentage of GDP (Source: US Department of Defense)

Figure) Trend of Defense Spending of China and the US as a Percentage of GDP (Source: Stockholm International Peace Research Institute)

The defense spending gap between China and the US is expected to gradually narrow, and by around 2050, China is likely to surpass the US in terms of the absolute amount of military expenditure. Considering that the US currently spends approximately 3.5% of its GDP annually and China spends about 1.7% of its GDP, sustained military spending can be anticipated in the future. However, there are voices within China advocating for increased military spending as a percentage of GDP, and the possibility of China matching US levels of military expenditure in the event of a full-scale military confrontation between the two nations cannot be disregarded.

As US military spending is global in scope, if we consider only the Indo-Pacific region, the military expenditure between China and the US is highly likely to be reversed given China's economic growth rate. Furthermore, both the US and China may exert pressure to increase defense-related research and development expenditures. In this process, China's defense spending burden will increase, becoming a pressure point for China's economic development and social welfare expenditures.

In March 2021, China announced an annual defense budget of 1.36 trillion yuan ($209.2 billion), a 6.8% increase from the 1.27 trillion yuan ($183.5 billion) spent in 2020. China's defense spending has increased nearly sixfold over the past two decades, surging from $41.2 billion in 2000 to $249 billion in 2020. China now spends more on defense than Japan, South Korea, the Philippines, and Vietnam combined. Its military expenditure ranks second globally, after that of the United States.

Since 2000, China's defense spending as a percentage of GDP has been subject to debate due to the opacity of its defense budget calculations, but it can be broadly estimated to be below 2%, approximately between 1.5% and 1.7%. When considered as a proportion of total government expenditure, China's military spending decreased from 11.3% in 2000 to 4.7% in 2020.

In contrast, US defense spending averaged approximately 3.9% of GDP from 2000 to 2020. In the US, after increasing from 2002 to 2011, military spending as a proportion of the budget also declined. It decreased from 9.6% in 2001 to 7.9% in 2020, falling back to pre-9/11 levels. As the world's hegemonic power, the US has, in cases of direct warfare, allocated separate war-fighting costs, leading to military spending reaching up to 5% of GDP. If a full-scale arms race with China were to occur, it is possible that defense spending would reach higher levels than at present. In the short term, due to the COVID-19 pandemic, US spending is focused on the domestic economy and healthcare, making the long-term outlook dependent on the US's economic development.

At the regional level, defense spending by various countries in East Asia increased from $91.1 billion in 1990 to $350 billion in 2020. The majority of this increase was driven by China, which accounted for 23.2% of total East Asian spending in 1990. As of 2020, China accounts for 69.8%. In a broader regional context, including continental Asia and the Middle East, China's military budget constitutes 39.5% of the total cumulative expenditure.

Looking ahead at future military spending, we can examine the figures as a percentage of GDP for both the US and China. China has already surpassed the US in GDP based on purchasing power parity in 2014, and it is projected that China will also surpass the US in nominal GDP by the late 2020s. Currently, the GDP of the US and China stands at approximately $20 trillion and $15 trillion, respectively, a ratio of about 4:3, with China's economy exceeding 70% of that of the US.

If China surpasses the US in the future and gradually widens the gap, the GDP difference between the two nations will increase. According to projections by the Japan Center for Economic Research, by around 2050, China's GDP could reach approximately $35 trillion, while the US's could be around $32 trillion. In such a scenario, even if defense spending levels remain the same, both the US and China would spend around $900 billion, potentially leading to parity or China's advantage depending on its spending level. Moreover, considering only defense spending focused on Asia, the US is currently projected to fall behind China in terms of defense expenditure.

Figure) Future Trend of US-China GDP (Source: Japan Center for Economic Research)

Conversely, the British accounting firm PwC anticipates an even stronger advantage for China. In this scenario, the US would be at a significant disadvantage in terms of defense spending differences between the two countries.

Based on this, if the US and China maintain their current defense spending as a percentage of GDP, the US can be expected to retain its advantage. However, as discussed earlier, the outcome could change if China increases its spending ratio.

Figure) Future US-China Military Spending Gap (Source: PwC)

Ben Herscovitch, a researcher at the Australian Centre for Independent Studies, argues that at the current trend, China's annual defense spending ($1.1 trillion) will surpass US spending ($900 billion) before 2050.

This situation could accelerate due to the COVID-19 pandemic. According to Bloomberg's analysis, the GDP gap between the US and China has narrowed by approximately 6 trillion yuan due to the pandemic, suggesting that future narrowing of the gap is highly dependent on the speed of economic recovery.

Figure) Trend of Narrowing US-China Economic Gap After COVID-19 (Source: Bloomberg)

2. US Strategy Towards China in Terms of Military Power and Strategy

Military strategy and weapon systems are crucial tools that can be used for deterrence, pressure, and even offense in the intense competition between the US and China. The US has been consistently developing its defense strategy to effectively deter and pressure China.

The US's future defense strategy is outlined in the National Security Strategy published in 2018. While only an executive summary has been released, more specific details are found in the research report titled "US Army Modernization: Hypercompetition and Theater Strategy in the Indo-Pacific" submitted by the Strategic Studies Institute (SSI) at the US Army War College to the Secretary of the Army.

The US argues that it must maximize its military power to counter China's strategy, assuming a future high-risk, hypercompetitive environment between the two nations. It asserts that by 2028, as US strategic advantage against China diminishes, the Indo-Pacific Command must possess qualitatively superior, rapid, resilient, and sufficient capabilities. In this context, the US contends that amidst ongoing military competition, it must develop strategies, plans, and operations for Joint Forces (JF) in a Multi-Domain Battle (MDO) environment to defend US interests within the Indo-Pacific Area of Responsibility (AOR). Korea is posited as a key theater responsible for deterring China's ground threats.

The US's most fundamental military pressure tactic against China is to strengthen its weapon systems, which remain vastly superior to China's, and its Indo-Pacific military strategy. In essence, multi-domain operations, maximizing synergistic effects across land, sea, air, cyber, and space forces, are the core components. The US perceives that China, through its anti-access, area-denial (A2AD) strategy, aims to maximize the obstruction of US military power projection in Asia and project its own military power to secure political and economic influence.

The concept of Multi-Domain Battle emerged in the US in 2016 and evolved into Multi-Domain Operations two years later, in 2018. Through this, the US military aims to create forces capable of competing with adversaries by integrating capabilities within a single theater, while also aiming to conduct multi-domain operations in two or more theaters, accounting for both China and Russia, by 2035.

As a comprehensive plan for multi-domain operations, the US intends to request $4.68 billion for the Pacific Deterrence Initiative, centered around the Indo-Pacific Command. This initiative is expected to trigger a similar arms race for China, which is also planning and pursuing multi-domain operations, thereby serving as a significant pressure point for China.

The strengthening of US military power in the Indo-Pacific is reflected in intensive military spending plans. The US is pursuing a deterrence strategy through the Pacific Deterrence Initiative (PDI) to mitigate risks, prevent escalation, and defend US interests in the Indo-Pacific through a practical and economically viable approach. To this end, it is setting expenditure levels for fiscal year 2022, with a budget of $4.6 billion, and plans for further increases. In addition to $4.68 billion for FY2022, the Indo-Pacific Command, according to a document reflecting its 2020 request, sought $226.9 billion to achieve its objectives from 2023 to 2027.

The demand for this increase in US military spending is concentrated in five focus areas for the Indo-Pacific Command: 1) military force repositioning and readiness; 2) exercises, experimentation, and innovation; 3) joint force lethality; 4) logistics and security support; and 5) strengthening alliances and partnerships. This is closely related to the strategy to counter China, with the primary objective being the deployment of integrated joint forces along the first island chain through a precision strike network west of the International Date Line.

Furthermore, it aims to provide missile defense along the second island chain and the capability to maintain stability and expand and sustain combat operations if necessary. To this end, it is presenting requirements for missile defense systems in Guam, with requests for $480 million for ground-based long-range fires in 2021 and plans to use $2.9 billion from 2023 to 2027. Additionally, it is pursuing air and sea mobility over distances exceeding 500 km for survivability and precision strikes.

For space-based persistent radar, $100 million is requested for FY2022, while the Indo-Pacific Command emphasizes the need for $2.2 billion for this item from FY2023 to FY2027. Additionally, $1.63 billion has been requested for "power projection, dispersal, and training facilities" within US territory, with plans to utilize $46.7 billion for this item from FY2023 to FY2027.

In the realm of military research and development, the US will pursue strategic concepts and weapon system development for multi-domain operations over the next decade, followed by the development of the Third Offset Strategy based on the Fourth Industrial Revolution. The US, with its long tradition in R&D, established the Strategic Capabilities Office (SCO) under DARPA in 2010 to conceive achievable programs and set goals that would yield innovative advantages. The SCO seeks new relative advantages in various operational domains by creatively mixing and reconfiguring existing technologies. Furthermore, to more efficiently introduce and militarize advanced civilian technologies, the Defense Innovation Unit-Experimental (DIUx) was established in 2015 to pursue new weapon technologies.

The military potential of new technologies and their convergence, integrated into warfare methods, is highly likely to lead to fundamental changes in how wars are fought, giving rise to new forms of warfare. The increasing outline of autonomous weapon systems combined with drones and artificial intelligence, and the possibility of robotic warfare, will transform the conduct of war and significantly impact the concept of human-centric war actors.

The US's Third Offset Strategy seeks technological innovation in five areas: development of autonomous deep learning systems, human-machine collaborative decision-making systems, enhancement of individual combat capabilities of human soldiers, improved mixed operations of human and unmanned systems, and development and operation of semi-autonomous weapons operating in future cyber and electronic warfare environments. The US is also actively engaged in related norm competition, continuously investing in autonomy, unmanned force teaming, and swarming. Ultimately, the Third Offset Strategy will pursue organizational innovation in parallel to capture the potential and limitations of operational concepts and technologies across both wartime and peacetime.

3. China's Strategy Towards the US in Terms of Military Power and Strategy

In terms of military buildup, weapon system development, and military strategy, China has relatively few pressure points against the US and primarily pursues defensive strategies. The anti-access, area-denial (A2/AD) strategy pursued by China is divided into two parts: 1) 'area denial' targeting the waters within 200 nautical miles of China's southeastern coastline, i.e., the first island chain, and 2) anti-access strategy targeting the second island chain, from 200 to 600 nautical miles. Area denial aims to impede and disrupt the free operation of adversary military forces deployed and operating within a given operational space, while anti-access refers to the concept of preventing or blocking adversary military forces from entering a specific operational space from a distance. It is assumed that China is focusing its military expansion on sequentially denying the US access to the first and second island chains.

China is attempting to compensate for its insufficient military power through gradual increases in military spending and R&D support, which could pose a structural challenge to the US in the long term. China's defense budget for 2021, disclosed at the 13th National People's Congress, was 1.3553 trillion yuan, a 6.8% increase from the previous year. At the time, China emphasized that this was an appropriate increase based on its projected economic growth rate of around 6% for the year. China's defense budget growth rate decreased from 10.1% in 2015 to 7.6% in 2016, followed by 7.0% (2017), 8.1% (2018), and 7.5% (2019). Last year, heavily impacted by the COVID-19 pandemic, it announced a defense budget increase rate of 6.6%, the lowest in the past 30 years.

However, the Stockholm International Peace Research Institute (SIPRI), based on its own analysis model, estimates that China's actual defense expenditure in 2019, which was announced as 1.213 trillion yuan, could reach 1.66 trillion yuan if hidden items such as arms imports and subsidies for People's Liberation Army-owned enterprises are included. This represents a 37% surge compared to China's announced figures, and global analysis institutions claim that such hidden expenditure items are concealed within China's defense budget.

The Center for Strategic and International Studies (CSIS) in the US points to the opacity of China's defense budget, noting that "the budget for the People's Armed Police directly under the Central Military Commission, the highest military body in China, the budget for space programs, and the budget for the Coast Guard are excluded from the defense budget items." China's defense budget, even based on official figures alone, exceeds the combined defense expenditures of Russia, Japan, South Korea, India, and Taiwan.

A 2018 report by the National Science Foundation (NSF) projected that China's research and development (R&D) expenditure may have already surpassed that of the US in that year. R&D expenditure is closely linked to the defense budget; between 2000 and 2017, China's average annual R&D investment growth rate was 17%, while the US's was only 4%.

Despite the uncertainties in forecasting China's economic growth in the 2020s, the Communist Party possesses the political will and financial capacity to consistently increase defense spending over the next decade. This will support the modernization of the People's Liberation Army (PLA) by utilizing various resources, including fostering a fused military-civilian defense industry, exploring new technologies for defense applications, investing in domestic defense, developing the domestic defense industry, expanding the scientific and technological base, and acquiring foreign technology and expertise. China's long-term objective is to create a fully self-reliant defense industry sector that integrates with a robust civilian industrial and technological base to meet the PLA's needs for modern capabilities, which will pose a long-term challenge to the US.

The PLA still faces limitations requiring the import of foreign equipment, technology, and knowledge to bridge critical short-term capability gaps and accelerate modernization. China will pursue efforts to enhance its military technology and expertise by leveraging foreign investment, commercial joint ventures, mergers and acquisitions, academic exchanges, the experience gained by Chinese students and researchers studying abroad, state-sponsored industrial and technological espionage, and circumvention of export controls.

Figure) R&D Investment by Country Based on GDP at Purchasing Power Parity

In response to the US military buildup, China is facing the need to develop anti-access and area-denial weapons at an even faster pace and is achieving steady results. In 2018, China unveiled the CM-401 anti-ship cruise missile (ASCM) produced by the China Aerospace Science and Industry Corporation (CASIC). CASIC's brochure describes the CM-401 as the 'world's fastest ASBM.' Additionally, China's MRBM DF-21 is equipped with a sensor system designed to track moving ships at sea. It can be armed with both conventional and nuclear warheads and has a range of 900-1000 miles. The Dongfeng-21D was developed with the intention of attacking large vessels such as aircraft carriers. The DF-26 is a ballistic missile with a strike range of 3,000-4,000 km, which can also be armed with both conventional and nuclear warheads and is considered China's first conventional ballistic missile capable of striking Guam. The strike range of the DF-26 includes most US military bases in the western Pacific. China is also working to develop re-entry vehicle and detection systems, as well as hypersonic warheads, which will pose a significant long-term pressure on the US and could exacerbate difficulties in US power projection in the Indo-Pacific.

Furthermore, China's development of hypersonic weapons is continuously progressing. In 2018, it tested a hypersonic vehicle named 'Xingkong-2' at missile launch sites in the Xinjiang and Inner Mongolia Autonomous Regions, developing several types of HGVs. At the 70th-anniversary military parade in October 2019, China unveiled the hypersonic ballistic missile DF-17. China announced in December 2017 that it had successfully test-fired the DF-17 equipped with a hypersonic glide vehicle. The DF-17, carrying a nuclear-capable hypersonic glide vehicle, flies at Mach 10 and can alter its trajectory during flight, reportedly allowing it to penetrate US missile defense (MD) systems. These hypersonic weapons pose a significant constraint on US aircraft carrier operations, forcing the US to develop new weapon systems and defense measures to counter them.

The nuclear arms race between the US and China currently shows a significant US advantage. China possesses approximately 300 nuclear warheads, and while it has a triad of delivery systems including intercontinental ballistic missiles, its capability to strike the US mainland with fighter jets or submarines is very limited. In contrast, the US's first-strike capability against China is overwhelming, to the extent that it is assessed as capable of neutralizing China's second-strike nuclear capability. However, with the future increase in China's nuclear capabilities, the need for nuclear balance or arms control between the US and China may grow. In such a scenario, the US advantage through nuclear attack would diminish, and China's pressure on the US would increase.

China's nuclear weapons policy has prioritized maintaining a nuclear force sufficient to inflict unacceptable damage on an adversary and survive a first strike. Over the next decade, China's nuclear warhead stockpile is expected to at least double as the PLA modernizes. Delivery systems will also advance in areas such as multiple independently targetable re-entry vehicles (MIRVs), stealth fighters, submarines, and hypersonic vehicles, increasing the nuclear threat to the US mainland. The projected changes in China's future nuclear forces and readiness are likely to outpace the US military buildup that could threaten China's retaliatory capability. Within this development, there is also the possibility of a change in China's existing no-first-use nuclear policy, which could lead to a new need for nuclear arms control between the US and China.

4. Mutual Pressure Through Alliance Strategies

Currently, the competition in security architecture in the Indo-Pacific region between the US and China, with the US's multi-layered alliance system, serves as a significant pressure point for China. China shares borders with 14 countries and is engaged in territorial disputes in the South China Sea and East China Sea with Southeast Asian nations and Japan, as well as land border disputes with India and others. In this context, the US can exert military pressure on China by providing active military support to countries experiencing border and maritime territorial disputes with China.

In addition to arms support, the US can employ pressure tactics such as acquiring rights to use military facilities like ports and bases, deploying troops, and sending military advisory groups to these countries. Simultaneously, a fundamental restructuring of the Asian alliance system to conduct multi-domain operations, along with the participation of European nations in Indo-Pacific operations, is expected to be pursued in the next phase.

Furthermore, efforts to strengthen military interoperability with allies are ongoing. The need to appropriately balance forward deployment and rotational deployment of US forces is being raised, and in this process, confidence-building with allies and partners will be enhanced. There is also a need to pursue distributed force posture and joint force deployment west of the International Date Line, maintaining a balance between lethality and survivability, and possessing the capability and authority to respond to contingencies.

China's response to this has so far been limited to the securitization strategy of the Belt and Road Initiative, but it is increasingly likely to evolve into an active offensive against US allies and partner nations, leveraging its economic power. China's military power projection and expeditionary capabilities pose a serious threat to US allies in Southeast Asia, which the US has defense treaties with or is obligated to defend as a result of security commitments.

If the US does not respond to China's aggression against its allies or partners, its credibility will be undermined. The loss of US allies and partners in East and Southeast Asia will inevitably affect not only US security and economic interests but also the viability of democratic governance in the region, as many US allies and partners are democratic nations. Therefore, if the US is to defend its allies or partners against China's offensive in the future, it must be prepared for the possibility of costly and prolonged conflicts, making the pressure on the US also significant.

In the event of a military conflict between the US and China, most Asian countries, as well as European nations like the UK and France, would desire a swift conclusion to the conflict with minimal damage to their own countries. Many nations, including Japan, would likely align with the US against China, but the degree of participation would vary. Australia and India are highly likely to engage in active military cooperation with the US, while South Korea would prefer to avoid direct military confrontation as much as possible.

III. Possibility and Changing Nature of US-China Military Conflict

1. Possibility of Escalation to Nuclear War

A military conflict between the US and China would have profound implications not only for the two nations but also for Asian countries and the global international community. If both the US and China were to seek victory through military means, they would need absolute certainty of victory and assurance that the conflict would not result in decisive damage to themselves.

Both the US and China are nuclear-armed states, and the possibility of their conflict escalating into a full-scale nuclear war cannot be disregarded. Currently, China possesses approximately 320 nuclear warheads and has a triad of delivery systems including intercontinental ballistic missiles, submarine-launched ballistic missiles, and fighter jets. However, if China's nuclear weapons were to target the US mainland, they would all be vulnerable to US defenses. The US possesses the capability to defend against China's intercontinental ballistic missiles with its strategic missile defense system, and China's submarines and fighter jets are highly likely to be detected and neutralized before reaching the US mainland.

The US could eliminate most of China's nuclear capabilities through a first strike. It is capable of a successful preemptive strike by detecting and neutralizing nuclear missile silos and mobile launchers, and removing nuclear warheads, thereby neutralizing China's second-strike nuclear capability. To date, China adheres to a strategy of minimum deterrence and a no-first-use policy, pursuing deterrence through retaliation by maintaining a minimum second-strike capability against nuclear attacks from external forces.

However, China is well aware of these issues, and as its overall military power improves, its nuclear capabilities and nuclear strategy are certain to evolve. China has the capacity to rapidly increase its nuclear warhead stockpile, increase the number of intercontinental ballistic missiles, and improve capabilities such as stealth fighters and nuclear submarines, thereby posing a threat to the US mainland. China is also developing its own missile defense systems, suggesting that a nuclear war between the US and China would increasingly result in mutually unbearable damage to both homelands.

If a military conflict between the US and China escalates to nuclear war, in a future scenario like 2050, both sides would suffer unbearable damage. Military facilities in both countries would be largely destroyed, conventional forces would be irrecoverably damaged, and post-war recovery would be nearly impossible if the capitals and major facilities of both nations were destroyed. Nuclear attacks on mainland China would entail damage to neighboring countries, and East Asian nations adjacent to China would also suffer secondary damage from a nuclear war.

Therefore, as both the US and China are well aware of the risks of nuclear war, future military conflicts between them will likely be confined to the scope of conventional warfare. The US will exercise considerable restraint in attacking China's homeland to eliminate its nuclear capabilities during a military conflict and will strive to avoid signaling that it could use nuclear attacks on mainland China as a military option. China, as long as it possesses the capability to launch nuclear attacks against the US mainland and US forces stationed in allied countries, will refrain from initiating a nuclear first strike against the US.

2. Possibility of Conflict over Taiwan

A military conflict between the US and China would be confined to the Asian region. Currently, the anticipated points of conflict between the US and China are Taiwan, the South China Sea, the East China Sea, the Korean Peninsula, and areas near China's Exclusive Economic Zone (EEZ).

China will not stand idly by while Taiwan declares independence or the United States enhances its military power in Taiwan. If the One China principle, which China has upheld until now, is weakened, it will be perceived as undermining China's sovereign interests. If its so-called core interests are infringed upon, China will mobilize its military to defend them, and thus China will seriously consider the use of military force against Taiwan, the United States, and its allies, even if the probability of winning a war is not high.

The unification of Taiwan holds a significant position in China's future strategy promoted by President Xi Jinping. China has succeeded in realizing the One China principle, by which countries including the United States have recognized China as the sole government since 1971. There has been no major change regarding the pursuit of gradual and peaceful unification through maintaining the status quo with Taiwan.

In the era of President Xi Jinping, China is pursuing a plan to complete the rejuvenation of China through the complete control of Hong Kong, Macau, Xinjiang, and Tibet, and further, the unification of Taiwan. The forced integration of Hong Kong has rendered China's commitment to the so-called "One Country, Two Systems" meaningless, and Taiwan, fearing China's coercive unification policy, is strengthening its relations with the United States.

Although President Xi Jinping's two terms are scheduled to end in 2022, he has not designated a successor, leading to speculation that he may pursue the presidency until the 2030s. There are also reports that discussions suggest President Xi Jinping is advancing the plan for building a strong military by 2035, bringing it forward by seven years to 2028. Viewed in this light, it is possible to observe that President Xi Jinping may attempt to unify Taiwan by military force after building a powerful military in the latter half of the 2020s.

As of 2021, China possesses overwhelming military power over Taiwan and believes it can militarily occupy Taiwan in a short period if the United States' extended nuclear deterrence and conventional military support for Taiwan are not guaranteed. If US support is secured, it is estimated that the US would also suffer significant damage but could prevent China's occupation of Taiwan. China would refrain from attacking Taiwan when the US demonstrates a clear commitment to ensuring Taiwan's security, but it could launch a military attack at any time if China's core interests, such as Taiwan's declaration of independence, are infringed upon.

China's military demonstrations towards Taiwan have become more frequent in the 2020s. In 2020 alone, Chinese aircraft entered Taiwan's Air Defense Identification Zone 380 times. In 2021, China's largest destroyer fleet passed through the Taiwan Strait, indicating a pursuit of strong military deterrence against Taiwan.

If China attempts to unify Taiwan by military force, it is projected to employ the following methods: first, destroy Taiwan's offensive capabilities through powerful missile and air strikes; second, impose a naval blockade to prevent support from the United States and its allies to Taiwan; third, utilize anti-access/area denial (A2/AD) military capabilities to prevent the entry of US fleets; and fourth, conduct an amphibious landing operation against Taiwan based on the above to achieve unification. This process could occur rapidly and in a short period, or it could involve a gradual strategy lasting several months to block external support to Taiwan and solidify its occupation. The crucial issue is how strongly the United States will militarily intervene if China attempts to unify Taiwan by force.

From the perspective of future military balance, China's superiority over Taiwan will become even more pronounced, and ultimately, the US's willingness to intervene will be crucial. However, from a military standpoint, the US's deterrent capability for maintaining the status quo will eventually face limitations. China's military buildup will enhance its ability to conduct a surprise occupation of Taiwan by weakening the reconnaissance and surveillance capabilities of the US and Taiwan. Ultimately, if military deterrence against China's occupation of Taiwan is not possible, diplomatic and political deterrence will become unavoidable.

In the case of Hong Kong, China's pressure did not elicit an effective opposition from the international community, and Hong Kong ultimately fell entirely under China's influence. If China were to militarily occupy and unify Taiwan, and if there were international sanctions that significantly threatened China's national strategy, it would be compelled to refrain from military action. This is not achievable by the United States alone but requires joint action from its allies and the international community. Diplomatic and political deterrence, and the maintenance of the status quo in Taiwan, are possible only when a clear and credible message is conveyed by the United States, its allies, and the international community regarding China's potential attack on Taiwan.

3. Possibility of Conflict in the South China Sea

The South China Sea is a critical maritime route through which 40% of global maritime trade passes. China claims maritime territorial sovereignty over the entire South China Sea. Despite disputes with Southeast Asian countries such as Vietnam, the Philippines, Indonesia, Brunei, and Taiwan, China will secure its maritime territory by militarily dominating the entire South China Sea if US military intervention is not guaranteed.

To date, China has been expanding its military influence in the South China Sea through the construction of artificial islands, the deployment of military facilities on islands in the South China Sea, the augmentation of its aircraft carrier fleet and blue-water navy, and a combination of appeasement and pressure tactics towards Southeast Asian countries.

In the next 30 years, if US military intervention weakens, military solidarity between the US and Asian countries weakens, and China gains influence over Southeast Asian countries, China's influence in the South China Sea will increase. If the US actively intervenes, the possibility of Chinese military victory is very low; however, if the US experiences a decline in national strength or strategic shifts, China will seize the South China Sea through active military action.

4. Possibility of Conflict in the East China Sea

The East China Sea is a region where China and Japan are in sharp confrontation over the Senkaku/Diaoyu Islands sovereignty dispute, continental shelf boundaries, and marine resource issues. Currently, the United States has firmly committed to military support for Japan concerning the East China Sea, making it highly unlikely that China could dominate the East China Sea with its military power.

Japan is also defending the East China Sea through continuous enhancement of its air and naval capabilities, securing US commitments, and has been continuously easing restrictions on the use of military force in conjunction with the US to dominate the East China Sea through legislative amendments.

In the future, even if China increases its military power, as long as the US-Japan alliance is maintained, US commitments to the East China Sea are firm, and Japan's military power is augmented, the probability of a military conflict primarily between the US and China, or China and Japan, in the East China Sea is low.

5. Possibility of Conflict on the Korean Peninsula

On the Korean Peninsula, the ROK-US alliance and the North Korea-China alliance are in opposition, creating a persistent possibility that a military conflict between the North and South could escalate into a military conflict between the US and China. The Korean War in 1950 already confirmed this possibility.

North Korea possesses deployed and usable nuclear strategies, thus a military confrontation between North and South Korea, or between North Korea and the US, has a very high probability of escalating into nuclear war. China, aware that a war on the Korean Peninsula would invite US intervention, is unlikely to preemptively initiate a war on the peninsula and is likely to restrain North Korea's use of military force.

However, if a conflict between the US and China occurs in areas such as Taiwan, the East China Sea, or the South China Sea, the US Forces Korea (USFK) could be redeployed and dispatched to conduct operations in those regions. China might then consider operations to blockade the Yellow Sea to prevent this, or cyberattacks against USFK bases.

More importantly, North Korea may seize the opportunity of US engagement in a war elsewhere to threaten or launch a military attack against South Korea. If USFK is dispatched to other regions in Asia, creating a military vacuum on the Korean Peninsula, there is a possibility that the situation on the Korean Peninsula could become linked with other conflicts in Asia. Looking ahead to around 2050, if the North Korean nuclear issue remains unresolved, North Korea exists as a nuclear state, and the North Korea-China alliance is strengthened, it is possible that a US-China military conflict in Asia could occur in conjunction with the Korean Peninsula.

IV. Damage to Both Countries in the Event of a Full-Scale US-China Conflict

If the US and China were to engage in a military conflict, it would result in not only military damage but also economic damage, domestic political repercussions, and changes in international prestige for both nations. As the military capabilities and weaponry of the US and China advance, the military damage they would sustain, even in victory, would be immense. The damage from a nuclear war would be unimaginably catastrophic, leading to mutual annihilation, and is therefore expected to be strictly avoided by both the US and China.

In the case of a conventional war, if it were a geographically limited, short-term, high-intensity conflict, the defeated nation would likely suffer asymmetrical damage, but both countries would still incur military losses. A military conflict between the US and China would likely involve not only naval and air combat but also cyber and space warfare, thus causing damage to the overall command and control (C2) systems. If cyber warfare were conducted against the opponent's homeland, or military bases of allies, or the homeland of allies, the damage would be even more extensive, extending beyond the military sphere to civilian sectors.

The economic damage would also be substantial. To date, the mutual trade dependency between the US and China has remained at a considerably high level. Even if the decoupling of trade, production, and supply chains between the US and China continues to some extent, economic damage will be unavoidable. Currently, China's economic dependence on the US is higher, and the US also has a high dependence on imports from China; therefore, the economic damage incurred by both countries in the event of a US-China conflict would be significant relative to their GDPs.

Figure) Mutual Trade Dependency between the US and China (Source: CEIC Database)

The RAND Corporation estimated the bilateral economic damage that the US and China would incur in the event of a military conflict, based on the year 2025 (Gomber 2016). The figure indicates that China would suffer greater economic damage than the US, reflected in the damage as a percentage of GDP for both countries. While the gap in damage between the US and China is small in the short term, calculations suggest that China's damage would increase relatively faster than the US's in the event of a prolonged conflict.

As the Indo-Pacific and Western Pacific regions become the theater of a US-China military conflict, China's economic activities would be severely curtailed. While the US does have significant economic dependence on the Indo-Pacific region, its geographical location would result in less damage compared to China.

Conversely, China's export and import routes would be affected, and investment in China would also significantly decrease. China, which relies on overseas energy imports, would also suffer considerable damage due to disruptions in energy transport routes.

Furthermore, if Asian countries cooperate with the US during a US-China military conflict, their trade and investment relations with China would shrink, leading to economic damage for China that is expected to be significantly greater than that incurred by the US.

Figure) Economic Damage to the US and China in the Event of a US-China Conflict in 2025

V. Conclusion

Overall, while the US holds a superior advantage in terms of pressure points in the security and military domains against China, this advantage will diminish over the long term. China will seek to accumulate leverage against the US over an extended period.

However, as leverage is mutually escalated, costs will increase, and ultimately, if military conflict becomes a reality, the damage to both sides across all sectors will be immense, creating a possibility for the avoidance of military conflict and the pursuit of reconciliation and adjustment after a short-term conflict. The US and China will face increasing military expenditures as a proportion of their national budgets and GDP due to continuous military spending increases, and also increased spending to expand their spheres of influence and strengthen alliances.

Most importantly, if military conflict between the two countries becomes a reality, they will suffer immense damage even in victory. Therefore, it is crucial for both the US and China, as well as for Asian countries and the international community, to visualize the expected outcomes and damages of a conflict to prevent it.■

[1] For further details, refer to Graham Allison, 2018, Destined for War: Can America and China Escape Thucydides's Trap? Seoul: Sejong Books.

[2] This situation is described in detail in the following book: Andrew Krepinevich, Barry Watts, 2019, The Strategist: Andrew Marshall and the Shaping of Modern American National Security Strategy. Seoul: Sallim.

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Author: Jeon Jae-seongDirector of EAI National Security Research Center, Professor at Seoul National University. He earned his Ph.D. in Political Science from Northwestern University and has served as President of the International Political Science Association and as a policy advisor to the Ministry of Foreign Affairs and the Ministry of Unification. His main research areas include international political theory, history of international relations, and studies on the ROK-U.S. alliance and the Korean Peninsula. His major works and edited volumes include "Threat of War and Peace Between North and South Korea" (co-authored), "Is Politics Moral?", and "East Asian International Politics: From History to Theory."

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