1. Introduction

The U.S.-Japan alliance has been one of the most important security frameworks in the Asia-Pacific region since the end of the Cold War, and its development has had a profound impact on the regional security landscape and China's national security strategy [1]. With China's rise, the United States and Japan have continuously strengthened bilateral military cooperation, including adjusting defense policies, intensifying joint military exercises, and promoting the Indo-Pacific strategy. These measures are viewed by China as threats to its security [2]. In international relations theory, the security dilemma explains such phenomena: defensive measures a country takes to enhance its security are often misinterpreted by other countries as threats, triggering an arms race and regional tensions [3]. In recent years, the Senkaku Islands dispute, the expansion of the US-Japan missile defense system, and policy statements on the Taiwan issue have become important factors affecting regional security and stability [4]. Against this backdrop, how the US-Japan alliance exacerbates China's security dilemma and its long-term impact on the regional security landscape have become key issues in international security studies.

This study adopts a literature review method to analyze the historical evolution of the US-Japan alliance, the applicability of the security dilemma theory, and China's response strategies to explore how the US-Japan alliance exacerbates China's security dilemma. This study provides a reference for future security governance, trust-building, and multilateral cooperation, helping to find a balance between competition and cooperation and avoid the security dilemma from evolving into real conflict.

2. Intensification of China's Security Dilemma

2.1. Military Pressure and Strategic Imbalance

The military deployment of the U.S.-Japan alliance in East Asia has significantly increased China's strategic concerns. In recent years, the U.S. has continuously expanded its military presence and equipment deployment in Japan, increasing the number of advanced military assets, such as F-35 fighters and the Aegis missile defense system while frequently carrying out high-intensity joint military exercises with Japan, which has significantly improved its military intervention capabilities in the region [5]. These initiatives are reflected in China's strategic perception as clear offensive signals. In particular, U.S.-Japan cooperation in the field of missile defense has led to China's perception that its strategic nuclear deterrence capability has suffered a severe weakening. China has thus been forced to invest significant resources in developing more penetrating hypersonic missiles, ballistic missile technology, and the continued enhancement of second-strike nuclear capabilities to deal with possible strategic imbalances [6].

Moreover, the U.S.-Japan alliance has expanded its strategic influence in China's neighboring regions, such as the East China Sea and South China Sea, by strengthening its military base infrastructure and intelligence-sharing capabilities, creating a sense of spatial pressure on China's military-strategic layout [5]. In response to these pressures, China has accelerated the modernization of its navy and air force and strengthened its "anti-intervention/area denial" (A2/AD) capabilities in order to weaken the U.S. and Japan's military superiority in the Asia-Pacific region and try to achieve a strategic balance [7].

2.2. Geopolitical Flashpoints Intensifying Perceptions of Threat

The U.S.-Japan alliance not only exacerbates China's strategic anxiety in military deployment but also promotes the spiral of security dilemmas on specific geopolitical issues such as the Diaoyu Islands and Taiwan. In 2012, the Japanese government "nationalized" the Diaoyu Islands, an action perceived by China as an attempt to strengthen its sovereignty claims and alter the regional status quo. As a result, China stepped up patrols in the East China Sea and dispatched more ships and aircraft into the disputed area [8]. Concurrently, the U.S. and Japan have conducted frequent joint military exercises and intelligence cooperation operations against China, making the Diaoyu Islands issue a sensitive focus of strategic interactions between the two sides.

Meanwhile, Taiwan has become another important trigger point for strategic competition among the United States, Japan, and China. In recent years, the U.S. and Japan have repeatedly emphasized the importance of peace and stability in the Taiwan Strait, with U.S. warships and aircraft frequently traversing the area. Additionally, Japan's political circles have also continuously sent signals to strengthen relations with Taiwan, such as joint military exercises and logistical support arrangements. These actions are interpreted by China as threatening interference in China's internal affairs and sovereignty and have led to increasingly active military actions by China in the direction of Taiwan. The risk of strategic confrontation in the Taiwan Strait region has significantly increased due to China's increasingly active military actions in the direction of Taiwan [9].

2.3. Dynamics of Misperception and Escalation Risks

The security dilemma theory emphasizes that defensive actions between countries are often perceived as offensive threats, thus creating a vicious cycle of strategic miscalculation and operational response [10]. The US and Japan's current series of military deployments and policy stances towards China are seen by Chinese strategic decision-makers as obvious signals of strategic squeeze and hostility. In contrast, China's countermeasures, such as upgrading the countermeasure capability of its strategic missile forces and expanding its military presence in the East and South China Seas, are seen by the US and Japan as concrete manifestations of China's military expansionist intentions [1]. Such mutual misinterpretations and reactions exacerbate mistrust and make strategic interactions more likely to slide into military confrontation and conflict.

Some scholars have pointed out that the structural security dilemma makes it difficult to perceive the goodwill of each party accurately, and even if the initial intention is the only defense, it is very easy to trigger the other party's overreaction, further reducing strategic mutual trust [10]. The spiral of this security dilemma makes short-term military confrontations more frequent and negatively impacts long-term regional security and stability. Especially in the absence of effective crisis management mechanisms and communication channels, the risk of miscalculation and uncontrolled strategic interactions between China, the United States, and Japan continues to rise. This dynamic contributes to a highly sensitive and fragile security situation in the Asia-Pacific region [11].

3. Strategic Competition and Regional Instability

3.1. Intensified Arms Race in East Asia

The strategic transformation of the U.S.-Japan alliance and China's military modernization process have accelerated the trend of an arms race in East Asia. According to a report from the Stockholm International Peace Research Institute (SIPRI), military spending by China, Japan, and the United States in the Asia-Pacific region has risen significantly in recent years. In 2024, China's military expenditure is projected to reach $313.6 billion, Japan's defense budget has increased to over $55 billion, and the United States is expected to invest up to $997.3 billion in the region [12]. The U.S.-Japan alliance in advanced military technology cooperation is also deepening. Japan plans to invest about 43 trillion yen (about $310 billion) in the next five years to strengthen its defense capabilities, including introducing long-range strike weapons and enhancing cyber defense capabilities [13]. This situation has further prompted China to countermeasures, leading to a spiral arms race escalation.

The arms race is not only limited to the increase in military spending and the number of equipment but also includes strategic deployment and base expansion. Frequent U.S.-Japanese military exercises in the Asia-Pacific region, especially in the South China Sea and the East China Sea, as well as the enhancement of the base infrastructure, have forced China to continue to expand its military capabilities, such as the construction of a new type of aircraft carriers and the increase in the frequency of submarine cruises, to maintain the strategic balance [14]. This military competition directly increases strategic risks in the region, deteriorates mutual trust, and exacerbates the security dilemma in the Asia-Pacific region.

3.2. Weakening of Multilateral Regional Security Mechanisms

Along with the intensification of strategic competition, the effectiveness of the original multilateral security mechanisms in East Asia has gradually weakened. The ASEAN-centered multilateral frameworks, such as the East Asia Summit (EAS) and the ASEAN Regional Forum (ARF), were originally designed to facilitate regional security dialogue and coordination. However, their effectiveness has diminished significantly due to the strengthening of the U.S.-Japan alliance and China's robust countermeasures in recent years [15]. ASEAN countries tend to adopt a "hedging" strategy. On the one hand, they welcome the presence of the United States and Japan as a counterbalance to China; on the other hand, they are also concerned that the big power game may push the region to the brink of conflict. This has gradually placed them in the dilemma of strategic decision-making [16].

In addition, the U.S.-Japanese QUAD mechanism, the U.S.-Britain-Australia Security Agreement (AUKUS), and other "small multilateral" cooperation frameworks may enhance short-term containment of China. However, they also exacerbate the fragmentation of the regional mechanism, weakening the ability of the region's unified security governance [17]. Correspondingly, China has also actively promoted the Shanghai Cooperation Organization (SCO) and the Regional Comprehensive Economic Partnership (RCEP), forming a regional cooperation structure in opposition to the U.S.-Japanese camp and further fragmenting regional security governance [18].

3.3. Strategic Polarization and Fragmented Security Architecture

The current security architecture in East Asia shows a clear trend of strategic polarization. On the one hand, the U.S. and Japan take the “Indo-Pacific Strategy” as the core and promote the security cooperation network with Western democracies through QUAD and AUKUS, which is targeting China. On the other hand, China has strengthened its strategic collaboration with Russia and other countries along the “Belt and Road,” forming a strategic partnership centered on China and Russia [19]. The polarization and confrontation of these strategic camps further aggravate the strategic uncertainty of regional countries. Against this backdrop, the security policies of regional countries have become increasingly polarized, and many countries have been forced to make a strategic choice between China, the United States, and Japan. This situation exacerbates the fragmentation and instability of the regional security landscape [20]. This fragmented security architecture increases the likelihood of regional conflict and makes it more challenging to construct a strategic mutual trust mechanism.

4. China’s Strategic Responses and Future Prospects

4.1. Military Modernization and Operational Adjustments

China has adopted a comprehensive military modernization strategy in response to the growing security pressures posed by the strengthening U.S.-Japan alliance. A central component of this strategy is the development of Anti-access/Area Denial (A2/AD) capabilities aimed at restricting the ability of the United States and its allies to project military power into China's near seas during a crisis. This strategy encompasses the deployment of intermediate-range anti-ship ballistic missiles (such as the DF-21D), the J-20 stealth fighter, air-launched cruise missiles, the BeiDou satellite navigation system, and the enhancement of the air force’s long-range strike capabilities [21].

Simultaneously, China is intensifying its development of information, electronic, and cyber warfare capabilities—often categorized under the “non-contact warfare” rubric—while accelerating its strategic deployment in outer space. These efforts are integral to the People's Liberation Army’s (PLA’s) broader objective of cultivating asymmetric warfare capabilities to exploit vulnerabilities in technologically superior adversaries. As the Congressional Research Service notes, China is building a comprehensive network of command, control, communications, computers, intelligence, surveillance, and reconnaissance (C4ISR) systems, along with space-based assets such as the Beidou navigation system and advanced electro-optical and radar satellites, to support long-range precision strike operations and enhance real-time targeting accuracy. This constellation of capabilities enables the PLA to challenge U.S. power projection in the Western Pacific without engaging in symmetric force-on-force competition [21]. By reshaping the battlespace through these strategic adjustments, China significantly raises the operational risks of potential U.S.-Japan military interventions, thereby contributing to a recalibration of regional strategic deterrence.

4.2. Diplomatic Balancing and Regional Engagement

Alongside its military modernization, China has consistently emphasized diplomacy and multilateral mechanisms to reduce regional security tensions and project strategic influence. Since the late 1990s, China has shifted from suspicion toward multilateral institutions to proactive participation, particularly through platforms such as ASEAN+1, ASEAN+3, the China–Japan–South Korea trilateral framework, and the Shanghai Cooperation Organization (SCO). These institutions offer China the opportunity to promote what it calls a "New Security Concept," advocating cooperative security, mutual respect, and regional leadership that is free from Cold War-style alliances [22].

This diplomatic posture gained momentum with China's articulation of the "Asian Security Concept" in the 2010s, which emphasized that "Asian affairs should be handled by Asians," implicitly challenging U.S.-led alliance structures in the region. China's goal is to establish a regional security architecture that is inclusive, dialogue-driven, and less dominated by traditional military blocs such as the U.S.-Japan alliance [22]. This vision has materialized through efforts to institutionalize relations with ASEAN via treaties, declarations, and the promotion of economic interdependence. As Shambaugh notes, China's deepening ties with ASEAN—manifested in initiatives such as the Declaration on the Conduct of Parties in the South China Sea and the China–ASEAN Free Trade Area—reflect a broader strategy of embedding itself in regional rules-making processes [22].

Moreover, China's approach toward Southeast Asia reveals a dual strategy of inducement and coercion. Le Thu describes how Beijing balances economic incentives—such as infrastructure investment and preferential trade—with implicit and psychological coercion, especially on sensitive issues like the South China Sea. While China promotes bilateral negotiations to fragment ASEAN's collective stance, it simultaneously discourages references to the "China threat" narrative in multilateral forums [23]. This approach has weakened ASEAN's institutional cohesion, eroded its centrality in regional diplomacy, and allowed China to reshape security discourse to reflect its interests.

Beyond Southeast Asia, China has extended its multilateral engagements across Central Asia, Africa, and the Global South. These relationships are framed under the image of China as a "responsible major power," seeking to enhance its normative appeal and strategic legitimacy. Kuik Cheng-Chwee argues that China's multilateralism is instrumental and strategic—motivated by the desire to hedge against U.S. containment and to shape regional norms and institutions in line with Chinese preferences [24]. As such, China's diplomatic balancing complements its complex power tools, facilitating a more resilient and autonomous regional order under its leadership.

4.3. Future Trajectories and Policy Recommendations

Looking forward, China’s strategic response to the intensifying pressure posed by the U.S.–Japan alliance will likely evolve along a dual trajectory of competitive management and limited stabilization. On the one hand, the continued advancement of the U.S. Indo-Pacific Strategy and Japan’s growing willingness to assume more assertive defense roles—such as the adoption of “proactive defense” principles—compel China further to enhance its strategic deterrence posture and operational flexibility to safeguard its core national interests and sovereign boundaries [1].

On the other hand, to avoid inadvertent escalation and misperceptions that could trigger a broader conflict, China must prioritize establishing bilateral and multilateral crisis management mechanisms. These include military hotlines with both the United States and Japan, renewed arms control dialogue, and institutionalized military-to-military communications to mitigate the structural dynamics of the security dilemma in East Asia [1]. As Christensen argues, the lack of confidence-building mechanisms and historically rooted mistrust renders the region particularly vulnerable to spiral tensions, especially in scenarios involving Taiwan or maritime disputes [1].

At the regional level, expanding practical cooperation, including joint unconventional security exercises with ASEAN nations or China-Japan maritime confidence-building pilots, might serve as a buffer to reduce the likelihood that localized confrontations escalate into systemic crises. Strengthening these “security buffers” may help partially offset the destabilizing effects of alliance reinforcement by the United States and Japan [25].

From a global perspective, China’s long-term strategic stability would benefit from greater transparency in its military intentions and a more consistent articulation of its regional security vision. The 2012 CSIS report by Armitage and Nye underscores that alliance partners like Japan should be encouraged to contribute to regional peace through enhanced capabilities and more deliberate diplomatic engagement. In that context, a Chinese strategy that combines limited competition with efforts to shape regional norms—rather than purely reacting to alliance expansion—may offer a more balanced path between confrontation and accommodation [25].

5. Conclusion

This study systematically analyzes how the U.S.–Japan alliance exacerbates China's security dilemma. It examines the strategic interactions among the three parties through the lenses of military deployments, geopolitical conflicts, and mechanisms of misperception. The study finds that the alliance has shifted from a traditionally defensive structure toward a more proactive and globalized security mechanism, increasing strategic pressure on China, which has responded with military modernization and deeper multilateral engagement. Furthermore, the study highlights deep-rooted divergences and historical memory which undermined mutual trust and increase the conflict risk. The structural contradictions between U.S.-led "minilateral" mechanisms and China's advocacy for an "Asia-led security order" contribute to regional instability.

Despite offering a structured explanatory framework through literature-based analysis, the study acknowledges limitations, such as the lack of quantitative data and firsthand accounts from policymakers. Future research could apply empirical methods to test the applicability of security dilemma theory in specific cases, such as the Diaoyu/Senkaku Islands crisis or military exercises around Taiwan.

Overall, constructing mechanisms for dialogue, enhancing transparency, and rebuilding trust amidst strategic rivalry are essential for future regional security governance. The United States, Japan, and China must each strive to define limits within competition and identify openings for cooperation to prevent the security dilemma from escalating into actual conflict.