The U.S. "Integrated Deterrence" Strategy and the Japan-U.S. Alliance: Sasebo Maritime Self-Defense Force Archives

Ahn Hyun · Hankuk University of Foreign Studies

Introduction

In 2023, the United States announced the adoption of an Integrated Deterrence strategy, signaling a more unified approach to deterrence. In response to this strategic shift, Japan has revised its three key security documents, modified its security strategy, and is working to build capabilities for the strategy by increasing defense spending and deploying missiles. Sasebo Port, a Japanese naval base, is a site undergoing transformation in line with the changes in the Integrated Deterrence strategy. This paper will first examine the background leading to the adoption of the Integrated Deterrence strategy and then outline its key components. Next, it will detail the Japan-U.S. alliance's efforts to implement the strategy and analyze the reasons behind Japan's active adoption of Integrated Deterrence despite various concerns. Finally, this paper will explore China's perception of Integrated Deterrence and the Japan-U.S. alliance. By examining the background of these changes, we aim to understand the direction and depth of the Japan-U.S. alliance's engagement, particularly concerning Sasebo Port, and to demonstrate that the alliance poses a challenge to China.

The U.S. Integrated Deterrence Strategy

Deterrence theory emerged after World War II as the United States sought to theoretically establish the use of nuclear weapons, and it has evolved and transformed in response to changes in the security environment. Since Jervis categorized these changes into three waves (Jervis, R. 1979), there have been a total of four waves up to the present day in 2023. The first wave refers to the initial deterrence theory proposed due to the necessity of the nuclear deterrence concept. The second wave involved the systematization within the theory. Following crises such as the Cuban Missile Crisis, which heightened tensions due to nuclear deterrence (Escalation), game theory and the assumption of rational actors were introduced into the theory to derive the conditions for deterrence success and failure. The third wave saw the emergence of the academic understanding that conventional deterrence could be incorporated into the theory, leading to a trend of developing deterrence theory through case studies. In addition to Jervis's classification, the argument arose that deterrence theory suitable for the post-Cold War security environment, which existing deterrence theories did not adequately cover, was needed. Notably, examples such as terrorism networks that emerged after 9/11 necessitated a revision of the assumption of rational actors, leading to the formation of the fourth wave of deterrence theory (Lupovici, A. 2010). In addition to these four waves, recent rapid changes in the security environment herald the emergence of new forms of deterrence. As new technologies such as artificial intelligence and quantum computing show potential for military applications, new technologies demand new forms of deterrence.

The United States recognizes this necessity and is striving to respond proactively through policy. U.S. Secretary of Defense Lloyd Austin announced "Integrated Deterrence" in his keynote address at the 40th Fullerton Forum in 2021 (Austin, L. 2021), outlining the general objectives of the new strategy that the U.S. Department of Defense would pursue. Furthermore, the 2022 National Defense Strategy (NDS) provided a more specific definition and implementation plan for Integrated Deterrence. Why did the United States adopt Integrated Deterrence? This chapter will first examine the process by which the United States adopted Integrated Deterrence and then explore the U.S. perception of the changing security environment.

History of the Adoption of Integrated Deterrence Strategy

4 Post-Cold War U.S. deterrence has been an adaptation process to the changing security environment identified by the fourth wave. Among these changes, four major shifts in the security environment have served as catalysts for the adoption of Integrated Deterrence. The first is the rise of China, which has already been extensively discussed. The second concerns the issue of multi-domain (Cross-Domain) operations; events such as China's anti-satellite missile tests and the cyberattacks used during Russia's annexation of Crimea signaled new threats of multi-domain attacks. Multi-domain attacks can be divided into two categories. The first is when the platform from which an attack is launched is in a different domain than the target platform. A prime example is an anti-satellite missile (ASAT) launched from the ground domain attacking a satellite in the space domain. The second refers to attacks conducted within a single domain with the intention of striking another domain. An example is attacking a satellite in space to disrupt ground operations (Manzo, V. 2011, 2). The U.S. perception was that there was a need to prevent adversaries from conducting such multi-domain attacks.

5 1. The U.S. "Integrated Deterrence" Strategy and the Japan-U.S. Alliance: Sasebo Maritime Self-Defense Force Archives

ASAT missile, a prime example of a multi-domain attack (Spencer, R. 2007). The third issue involved new domains. There were concerns about U.S. vulnerabilities in new domains such as space and cyberspace. The need arose to prepare for scenarios where China and Russia, leveraging their relatively lower vulnerabilities in these domains, might threaten or invade the U.S. and its allies. The fourth factor was the relative decline of U.S. power. Since the Great Recession of 2008, hostile actions by challenging states have increased. Examples such as Russia's 2008 war in South Ossetia and its 2014 annexation of Crimea are considered failures of U.S. deterrence, and clashes in the South China Sea, such as the Senkaku Islands issue, have also become more frequent during this period. Furthermore, distrust among allies that emerged after the Trump administration

6 made it difficult for the alliance to respond consistently to challenging behaviors.

Integrated Deterrence is a new form of deterrence devised to counter these four problems, as further detailed in the NDS. First, the NDS identifies China, Russia, North Korea, and Iran as entities posing threats to the United States. China, in particular, is regarded as "the most comprehensive and serious challenge to U.S. security due to its coercive and increasingly aggressive attempts." Furthermore, the NDS states that the Chinese Communist Party pursues a "holistic" approach and that "Integrated Deterrence is necessary as a holistic response" to counter these challenges. This indicates that China's deterrence is being reorganized under the concept of "Integrated Strategic Deterrence," and countering China's strategy is one of the primary objectives of Integrated Deterrence.

Second, the NDS signals an enhancement of capabilities to counter multi-domain attacks. In addition to traditional deterrence methods such as "Deterrence by Denial" and "Deterrence by Direct & Collective Cost Imposition," the NDS introduces "Deterrence by Resilience" as a new form of deterrence. This plan aims to increase the resilience of U.S. forces and allied forces stationed in the Indo-Pacific region to counter multi-domain attacks, including gray-zone operations (Scouras, J., Smyth, E., & Mahnken, T. 2017, 7) (Chase, M & Chan, A. 2016, 1). Third, the NDS announces that "space and cyber domains will be prioritized for enhancement," reflecting research indicating that China perceives U.S. reliance on space and cyber domains as an opportunity, while the U.S. lacks sufficient strategies to deter threats in these domains (Scouras, J., Smyth, E., & Mahnken, T. 2017, 7). The NDS proposes countermeasures such as investments to maintain U.S. superiority in these domains.

Finally, the NDS emphasizes the importance of competitors understanding U.S. intentions and capabilities to prevent competition from escalating into unintended conflict. As Schelling argued, it is crucial for the deterring party and the deterred party to share a common language, situational awareness, and conditions for punishment (Schelling, T. 1966, 146-148). This is because it is essential for the deterred party to clearly perceive the limits set by the deterring party to prevent miscalculation and ensure clear signal recognition, thereby avoiding unintended conflict. The naming of Integrated Deterrence serves as a signal from the United States that it can identify and deter China's actions aimed at achieving its political and military objectives by exploiting vulnerabilities and ambiguities. Furthermore, responses from allies and the United States to implement Integrated Deterrence have been presented, which will be discussed in the following chapter.

8 Synthesizing the historical background described above, the four changes in the security environment that have occurred since the end of the Cold War have served as the backdrop for the adoption of U.S. Integrated Deterrence. The United States has formulated the Integrated Deterrence strategy to respond to these changes. As long as the threats posed by the evolving security environment persist, it is reasonable to assume that the core elements of Integrated Deterrence will not be easily altered.

U.S. Academic Perceptions of Integrated Deterrence Following the concretization of the Integrated Deterrence strategy in the 2022 NDS, various discussions have emerged within U.S. academia regarding this strategy. A common perception is that concrete methods for evaluating the strategy have not yet been established. However, based on the content presented thus far, several arguments have been put forth, with the most contentious issue being whether the integration of non-military means, as presented in the NDS, is appropriate as a tool for deterrence. Critical scholars argue that developing clear military means is crucial for effective deterrence (Spoehr, T. 2021). They cite research indicating that non-military means such as economic sanctions and diplomatic rhetoric have limited utility in deterrence, and they point out that if Integrated Deterrence's direction emphasizes non-military means beyond what is necessary, it is a misguided path.

9 1. The U.S. "Integrated Deterrence" Strategy and the Japan-U.S. Alliance: Sasebo Maritime Self-Defense Force Archives

In contrast, scholars who advocate for the strategy argue that the NDS emphasizes interagency cooperation for a comprehensive approach and that the Department of Defense still emphasizes military means. They point out that the NDS primarily focuses on the utilization and development of military capabilities, merely mentioning the importance of cooperation with other agencies regarding other means (Sisson, M. 2022). Furthermore, arguments are being made that this approach is valid by focusing on interagency cooperation. For Integrated Deterrence to succeed, other agencies must first accept the concepts proposed by the Department of Defense, enabling the government to convey a consistent message and actions to ensure intentions are understood. These arguments emphasize the psychological aspect of deterrence, asserting that the NDS correctly recognizes the importance of consistency in signals sent to the target of deterrence (Mclnnis, K. 2022). There is also the argument that deterrence is effective when conducted in the short term, buying time for diplomatic conflict resolution, and that the NDS should address coercive means in situations of deterrence failure from a long-term perspective (Monaghan, S 2023).

The first point of contention falls outside the scope of this paper. Developing the capacity to comprehensively mobilize the means handled by various agencies within the United States can be considered a domestic issue. While the importance of capabilities that ensure deterrence success can be emphasized, the U.S. Department of Defense appears to recognize the importance of these capabilities (Austin, L 2023). The second point of contention, the consistency of signals, is what this paper will focus on. The allies of the United States, who are co-providers of deterrence and its beneficiaries, are also subjects who receive and interpret signals, and the judgment of these allies warrants detailed discussion.

10 The importance of capabilities that ensure deterrence success can be emphasized, but the U.S. Department of Defense appears to recognize the importance of these capabilities (Austin, L 2023). The second point of contention, the consistency of signals, is what this paper will focus on. The allies of the United States, who are co-providers of deterrence and its beneficiaries, are also subjects who receive and interpret signals, and the judgment of these allies warrants detailed discussion.

Integrated Deterrence Strategy and the Japan-U.S. Alliance

What is the role of allies in the U.S. Integrated Deterrence strategy, and how are these allies accepting it? This chapter will first examine Japan's role in the Indo-Pacific region as envisioned by the United States, focusing on the NDS and the Japan-U.S. Security Consultative Committee (2+2 Meeting). Based on these findings, we will then examine how Japan is policy-wise embracing Integrated Deterrence through the Japanese Defense White Paper and the process and content of the revision of the three key documents.

Japan's Role as Presented in the Integrated Deterrence Strategy A consistent phrase appears in Secretary Austin's remarks. According to him, Integrated Deterrence involves utilizing existing capabilities in the short term, developing new capabilities, and employing all capabilities in a networked manner with allies and partners (Department of Defense 2023, 8). He outlines the direction of Integrated Deterrence at a macro level in three parts. Furthermore, the NDS refers to Japan as a key partner and an ally that plays a central role in developing new capabilities and employing them in a networked manner. Specifically, cooperation with Japan as outlined in the NDS includes the following:

First, cooperation with Japan is mentioned in the section on the application of the Integrated Deterrence strategy to the Indo-Pacific region (Department of Defense 2023, 15-16). The integration of strategy planning and capabilities in a modernized and coordinated manner with Japan is a specifically stated key area of cooperation. Second, in the section discussing "Integrated Extended Deterrence," Japan is mentioned alongside South Korea and Australia as a country participating in the decision-making process for nuclear deterrence policy. Third, in the section on the application of Missile Defense (MD) to the Indo-Pacific region, Japan is mentioned as a cooperation partner along with South Korea and Australia in the development of missile defense systems. The above mentions highlight Japan's importance in implementing the Integrated Deterrence strategy. While the NDS indicates cooperation with other countries in more limited scopes—for example, it primarily limits South Korea's role to deterring North Korea—Japan is designated for the entire Indo-Pacific region. However, the NDS does not provide specific details on the cooperation between the U.S. and Japan for the Integrated Deterrence strategy, which can be supplemented by examining the outcomes of the 2+2 meetings.

12 This can be supplemented by examining the outcomes of the 2+2 meetings.

Photo from the 2023 2+2 Meeting (The Asahi Shimbun 2023).

The outcome documents of the 2+2 meetings allow us to understand the specific discussions on Integrated Deterrence between Japan and the U.S., and the alignment of these documents reveals the shared positions of both countries. The two U.S. secretaries described the publication of the revised three key documents—the National Security Strategy and the National Defense Strategy—as having "unprecedented alignment." Given that the corresponding U.S. NDS was adopted on October 27, 2022, and the document revisions were adopted on December 16 of the same year, the assessment by the two U.S. secretaries appears to emphasize that Japan's strategy had aligned with their Integrated Deterrence strategy in a short period. The convergence of the two countries' new security and defense strategies in an integrated manner is also highlighted, indicating the U.S. perception that Japan has appropriately recognized and policy-wise adopted its signals. As a reward for this alignment, the U.S. has increased its commitment level by confirming that the Senkaku Islands are covered by Article 5 (the intervention clause) of the U.S.-Japan Security Treaty.

The latter part of the document outlines the alliance's roles and tasks in five areas: (1) Alliance Cooperation, (2) Combined Efforts in Peacetime, (3) Combined Efforts for Deterrence and Response, (4) Space, Cyber, and Information Security, and (5) Maintaining Technological Superiority. The specific items mentioned relate to the aforementioned direction of Integrated Deterrence, so we will organize the policy-relevant items by area.

Area Area-Specific Details (1) Alliance Cooperation Establishment of a Permanent Joint Headquarters (PJHQ) for the Self-Defense Forces

14 (2) Combined Efforts in Peacetime Expansion of ammunition depots at Kadena Air Base, Air Self-Defense Force /

Increased joint use of U.S. and Japanese facilities / Japan

Increased military exercises in regions including the Southwest Islands

increase

(3) Combined Efforts for Deterrence and Response Enhanced capabilities in mission areas such as integrated air and missile defense, anti-ship warfare, anti-submarine warfare, mine countermeasures, amphibious and airborne operations, ISRT, logistics, and maneuver

/ Strengthening multi-domain capabilities integrating air, sea, land, space, cyber,

and the electromagnetic spectrum, among other domains.

enhanced multi-domain capabilities

(4) Space, Cyber, and Information Security Operation of Japan's Space Situational Awareness System and cooperation in space intelligence (quantum) / Air Self-Defense Force

Cyber Defense Command establishment / (Cyber) risk management

framework adoption / Cybersecurity standards establishment for the defense industry

security standards establishment

(5) Maintaining Technological Superiority Memorandum of Understanding on research, development, experimentation, and evaluation projects

signed, discussion on mutual government quality assurance / High-power microwave and autonomous systems joint research

project discussions

project discussions

15 1. The U.S. "Integrated Deterrence" Strategy and the Japan-U.S. Alliance: Sasebo Maritime Self-Defense Force Archives

Among the examples listed above, some are particularly noteworthy. As mentioned earlier, Integrated Deterrence involves utilizing existing capabilities in the short term, developing new capabilities, and employing all capabilities in a networked manner with allies and partners. Japan is implementing and developing specific policies to enhance its defense capabilities in line with the direction set by the United States. A prime example is the planned establishment of a Permanent Joint Headquarters (PJHQ). The PJHQ is a unit of the Self-Defense Forces that will be responsible for the integrated command of the Ground, Maritime, and Air Self-Defense Forces. While Japan's military organization already includes the Joint Staff Office, which performs a role similar to South Korea's Joint Chiefs of Staff, the establishment of a new PJHQ can be seen as fulfilling the need for a dedicated department to conduct Integrated Deterrence with the United States, in addition to domestic demands.

Discussions about establishing a PJHQ had occurred previously, but more serious deliberations began after the Great East Japan Earthquake in 2011. During the cooperation between the U.S. military and the Japan Self-Defense Forces in disaster response, the Japan SDF experienced communication difficulties due to the absence of a counterpart. Without an entity corresponding to the U.S. Indo-Pacific Command (INDOPACOM), the Chairman of the Joint Staff had to simultaneously deal with the Chairman of the U.S. Joint Chiefs of Staff and the Commander of INDOPACOM, creating significant challenges. However, various domestic and international concerns delayed its establishment.

16 Domestically, there were concerns about potential duplication of command structures, as the Joint Staff Office already existed. Internationally, there were concerns that the emergence of a powerful integrated command authority for the three branches of the SDF could lead to a resurgence of militaristic tendencies, reminiscent of the Japanese Empire era (Isobe Koichi. 2023). These concerns prevented the establishment of the unit for 12 years, but work only began in earnest after the advent of Integrated Deterrence. The purpose of establishing the PJHQ, as indicated in Japan's NDS, is likely to conduct cross-domain operations in an integrated manner (Ministry of Defense 2023, 15, 249, 281). The connection to the Integrated Deterrence strategy is evident through the consistency of terminology and background.

As demonstrated by the examples above, Japan is rapidly strengthening and reorganizing its defense capabilities in line with the concept of Integrated Deterrence proposed by the United States. What prompted these changes? What enabled Japan to quickly and accurately grasp the signals sent by the United States? The following section will explore the reasons behind this by examining Japan's perceptions.

17 1. The U.S. "Integrated Deterrence" Strategy and the Japan-U.S. Alliance: Sasebo Maritime Self-Defense Force Archives Reorganization of Japan's Defense Capabilities under the Integrated Deterrence Strategy

17 1. US "Integrated Deterrence" Strategy and the Japan-US Alliance_Reorganization of Japan's Defense Capabilities under the Integrated Deterrence Strategy at the Sasebo Maritime Self-Defense Force Historical Archives

As mentioned earlier, Japan revised its three key documents approximately two months after the U.S. NDS was released in 2022. The content of these revisions was praised by the U.S. Secretaries of Defense and State in early 2023 for its alignment with their own national strategies. The use of the term "unprecedented" suggests that there was a fundamental shift compared to previous changes. So, what specific changes have occurred?

Japan has interpreted Article 9 of the Constitution of Japan (also known as the pacifist constitution) within a limited scope during the Cold War era. However, it is also true that the interpretation has undergone repeated changes according to the evolving security environment. Changes in interpretation were confined to the legal dimension until the revision of the three major documents in 2022. First, in 1999, the Act on Security and Safety of Areas Surrounding Japan (周辺事態安全確保法), which stipulated the scope of possible US-Japan cooperation under the pacifist constitution during emergencies, was passed. Next, in 2015, two laws related to the peace and security legislation (平和安全法制), which changed the cabinet's view on collective self-defense, were passed. We can find three commonalities from these two documents.

First, both documents were legal endeavors to enable the exercise of collective self-defense while adhering to the pacifist constitution. Second,

the periods of revision in 18 were triggered by threats from neighboring countries, namely North Korea's nuclear and missile tests and the Senkaku Islands dispute. (Watanabe Tsuneo 2023). Third, the cabinet cited demands arising from cooperation with the United States during the revision process as grounds for the amendments (参議院. 1999). Looking at these legal aspects, the changed interpretation appears to be an attempt by Japan to establish grounds for exercising collective self-defense due to security threats and US demands. However, examining specific security policies, it is difficult to conclude that Japan was in the process of preparing to exercise collective self-defense. For example, the 2015 Defense White Paper foreshadows the commencement of development for the Amphibious Rapid Deployment Brigade and hypersonic missiles due to changes in the security environment, such as gray zone tactics, but this should be considered in relation to the exercise of individual self-defense.

In contrast to these existing trends, the revisions to the three major documents in 2022 suggest that policies for exercising collective self-defense will be more actively introduced. The revisions indicate that Japan has set two objectives at the strategic level. The first is the optimal and efficient use of existing equipment. It is anticipated that defense investment facilities will be strengthened to increase operational rates, secure adequate ammunition and fuel, and enhance resilience. The second is the development of core capabilities for future operations. Specific implementation measures include strengthening organically integrated capabilities across land, sea, air, space, cyber, and electromagnetic domains to respond to multi-domain operations in a multi-layered manner. Furthermore, the necessity of stand-off defense capabilities to counter invasion and attacks from outside the threat area is also emphasized (Ministry of Defense 2022).

Japan presents the establishment of a strategy corresponding to the US NDS published in the same year (Align respective strategies) as an objective in the early part of the new NDS publication, and this can also be confirmed by the conceptual similarity. As mentioned earlier, the definition of integrated deterrence presented by the United States is to efficiently use existing capabilities in the short term, develop new capabilities, and utilize all capabilities in a networked manner with allies and partners. Within this framework, Japan's documents can be organized as follows.

US NDS Japan NDS Objectives in the 3 major documents Objectives Implementation measures Specified implementation measures Existing Optimal and efficient use of existing equipment / Enhancement of operational rate / Securing fuel and ammunition / Strengthening resilient defense facilities / Expansion of military training / Joint use of Nansei Islands / Kadena Base Ammunition Depot Expansion

New Future Ground, Sea, Air, Space Situational Awareness Capabilities for Operations / Space, Cyber, and Systems Domain / Strengthening Integrated Capabilities / Air Self-Defense Force

Strengthening Stand-off Defense Capabilities / Cyber

Defense Command Establishment

/ R&D

/ R&D

Memorandum of Understanding / High-Power

Microwave and

Autonomous Systems Collaboration

Discussion

Integrated deterrence and response capabilities of allies / Strengthening US-Japan Alliance / Permanent Integrated Command Establishment / Air and

Coordination mechanism (ACM) between US and Japan / Missile Defense /

Missile Defense /

Enhancement, and renewal / Acquisition and Cross-Servicing Agreement (ACSA) / Surface warfare, anti-submarine warfare,

Strategy and Air Assault Operations, ISRT,

Strategy and Air Assault Operations, ISRT,

Presentation Reciprocal Access Agreement (RAA) Logistics, Maneuver Missions

Facilitation / Key

21 1.US Integrated Deterrence Strategy and US-Japan Alliance_Sasebo JMSDF Historical Archives

Countries (NATO, South Korea, Domain Enhancement

Australia, India, etc.)

Bilateral Cooperation

Among the presented items, the capability Japan currently prioritizes most is stand-off defense capability, which can also be confirmed in the budget. The 2023 Defense White Paper of Japan (Ministry of Defense 2023, 263-275) outlines the approximate defense budget, indicating that out of a total of 43.5 trillion yen (US$304 billion), a certain amount will be allocated to the seven major defense capability development goals. The item with the largest expenditure, 9 trillion yen, will be for sustainability and resilience. This item specifically includes ammunition and missiles, maintenance, and facility enhancements. The next largest expenditure is for stand-off defense capability, with an anticipated spending of 5 trillion yen. Stand-off defense capability refers to the ability to strike an enemy from outside their threat range, and can primarily be understood as missile capability. Japan's existing missile defense capabilities have primarily focused on missile interception. However, starting with Prime Minister Shinzo Abe in 2017, some within the Liberal Democratic Party began to emphasize the need for rapid response capabilities in addition to defense systems. These arguments gained further traction as missiles capable of neutralizing existing defense systems, such as hypersonic missiles, were developed in China, Russia, and North Korea (自由民主党 政務 調査会 2020).

22 These missiles, capable of neutralizing existing defense systems, were developed in China, Russia, and North Korea, lending further weight to these arguments. (自由民主党 政務 調査会 2020).

Budget by Seven Items

As part of the effort to build stand-off defense capabilities, Japan has revised its previous policy of introducing the Aegis Ashore system and decided to introduce new Aegis destroyers capable of ballistic missile interception. In particular, these Aegis destroyers are expected to fill a power vacuum in the East Sea while existing vessels operate near Okinawa (Ministry of Defense 2023, 16). Next, for stand-off defense capabilities, Japan has decided to introduce 200 of the 400 US-made Tomahawk missiles it had previously planned to acquire, one year earlier in 2025 (Ken Moriyasu, Yusuke Takeuchi. 2023). This is focused on securing stand-off defense capabilities by 2026, when its own new cruise missiles are scheduled for introduction. The decision to reverse the introduction plan at the end of 2022 to fill a one-year introduction gap can be seen as an indication of the Japanese government's strong threat perception.

This focus on securing stand-off defense capabilities by 2026, and the reversal of the introduction decision at the end of 2022 to fill a mere one-year gap, suggests the strength of the Japanese government's threat perception.

24 Landing points of missiles fired during Chinese military exercises following Pelosi's visit.

(Katsuji Nakazawa 2022).

Japan's heightened threat perception appears to be the background for Japan becoming the most aligned country with the US integrated deterrence strategy. Japan's threat perception is even stronger than that of the United States. In a public opinion poll conducted by the Japanese government in 2023, 85.5% of respondents answered that Japan could be a target of attack or involved in armed conflict, and 89.7% answered that the US-Japan Security Treaty is helpful to Japan. The proportion of respondents satisfied with Japan's current military capabilities also decreased by about 7% compared to the previous year, standing at 53% (Takahashi Kosuke 2023). The incident where five out of nine missiles launched by China the day after Nancy Pelosi's visit in 2022 landed within Japan's exclusive economic zone has led to a heightened threat perception in Japan. The intensification of the medium-range missile competition within the region, due to the US withdrawal from the INF Treaty and China's development of hypersonic missiles and expansion of its nuclear arsenal, is also a major background for Japan's defense capability enhancement.

In summary, the Japanese government perceives a high likelihood of armed conflict in the short term due to its threat perception, as confirmed through documents such as defense white papers and public opinion surveys. Japan's own defense capability enhancement focuses on strengthening existing capabilities to withstand attacks during contingencies (Resilience) and ensure smooth and continuous command, control, and ammunition supply with the United States (Sustainable). While new capabilities are being developed in space and cyber domains, the focus is on securing missile strike capabilities, specifically stand-off strike capabilities. Cooperation at a foundational level for situational awareness sharing is underway between the US and Japan in 2023. Japan's assumed armed conflict prioritizes the defense of its territorial waters and exclusive economic zones in the southwestern Pacific and deterrence in the Taiwan region, with North Korea's missile threat being a secondary consideration.

US-Japan Solidarity under the Integrated Deterrence Strategy and China

China's perception, the direct target of integrated deterrence, can be found in the "Modern International Relations 2023, Issue 6" published by the China Institute of Contemporary International Relations (中国现代国际关系研究院). The analysis points out that integrated deterrence can threaten the security of the Asia-Pacific region by creating three major contradictions (陈庆鸿 2023).

The three contradictions they argue are as follows. First, the contradiction between militarization and economization. It is pointed out that since countries in the Asia-Pacific region prioritize economic development, participation in integrated deterrence could hinder their development. Second, the contradiction of autonomy. Integrated deterrence requires securing regional bases and integrating the military means of allied nations, which could undermine the sovereignty of allied nations by violating neutrality and imposing operational constraints. Third, there is a contradiction where integrated deterrence leads to deterrence failure. This analysis cites Schelling's argument that the effectiveness of threats lies in the alternatives available to potential adversaries, arguing that integrated deterrence may reduce non-military alternatives. The analysis concludes that these three contradictions make integrated deterrence itself likely to fail. It is presumed that the coordination of allies participating in integrated deterrence will be limited due to issues such as US domestic politics, and that increased tensions in the Western Pacific will lead to widespread opposition and failure.

China also perceives the strengthened cooperation between the US and Japan negatively. China criticizes Japan's capability enhancement for integrated deterrence, as discussed earlier, as "militarization" in a historical context (Reuters 2023). Regarding integrated deterrence, the area of greatest concern for China in 2023 is medium-range missiles. China is reacting sensitively to reports that the US may deploy medium-range missiles in the Asia-Pacific region (Patrick Tucker 2023) and reports of Japan's early deployment of improved anti-ship missiles. Chinese experts view the deployment of cruise missiles such as the SM-6 and Tomahawk as having limited destructive power, but consider the nature of the incident similar to the Cuban Missile Crisis (Zhang Han 2023). These arguments have some validity. From Japan's perspective, it is pointed out by Japanese experts that the need for actual combat capability and efficiency arising from Japan's participation in the integrated deterrence strategy may conflict with Japan's prolonged recession and aging population (Takuya Matsuda 2023). The sustainability of the integrated deterrence strategy itself is also questioned due to the experience of the Trump administration.

However, Japan's policy of strengthening its capabilities and enhancing its alliance with the United States for integrated deterrence is unlikely to change in the near future. As mentioned earlier, Japan's recent actions, which China views with caution, stem from Japan's threat perception. And the events that triggered that threat perception were based on China's new military strategy. China presented limited strikes as a means of deterrence in its 2020 strategy publication by the Institute of Military Strategy, Academy of Military Science of the Chinese People's Liberation Army. The strategy mentions that warning-demonstration military strikes targeting relatively isolated and easily struck military and political targets can be carried out for deterrence (中国军事科 学院军事战略 研究所 2020, 136), and based on this

Autonomous Systems Joint

Conclusion

Artificial Intelligence (AI) is the core capability required for both the United States' Integrated Deterrence and China's Integrated Strategic Deterrence. Both nations share the necessity of AI technology to efficiently perform complex tasks involving the integration of domains, diverse forms of conflict, and the capabilities of military, non-military sectors, and allies. Consequently, they are engaged in fierce competition over AI development. The United States identifies AI's core capability as assisting decision-makers in making swift and accurate decisions (Department of Defense 2023, 3). Since Xi Jinping's mention of the 'three-ization' concept—mechanization, informatization, and intelligentization—at the 20th National Congress of the Communist Party of China (新华网 2022), China has also recognized the importance of AI's military application in line with intelligentization, as evident in various documents. Specifically, it is analyzed that "in the era of intelligentization, if package software and core algorithms lag behind, operational potential cannot be realized even with high hardware performance" (李志飞 2022), foreshadowing the development of AI in conjunction with existing military means. In this paper, we examined the aspects of Japan's participation as a key actor in the Integrated Deterrence strategy established by the United States and its background. Integrated Deterrence has emerged as a new U.S. strategy to deter China, and Japan is strengthening its own capabilities in alignment with this strategy. As discussed earlier, developing AI, a core capability, requires the support of a physical foundation in advanced semiconductor production capacity (Kim Yang-gyu 2024). Japan accounts for approximately 35% of the semiconductor manufacturing equipment market and about 50% of material production. The situation where the U.S. and Japan hinder China's AI development under the Integrated Deterrence strategy will pose a significant challenge to China. In particular, as the implementation of the Integrated Deterrence strategy leads to a shift towards complex competition beyond traditional military strategy dimensions, including competition in new domains such as space and cyberspace, and technological development competition in areas like semiconductors, China's calculations will become increasingly difficult.

China has adopted a new military strategy called "Integrated Strategic Deterrence" and has reorganized its capabilities accordingly, even down to the operational level. However, paradoxically, these preemptive measures have heightened Japan's threat perception,

30 and consequently strengthened US-Japan solidarity. In other words, China's strategy has narrowed its own strategic horizon, making it difficult to achieve its strategic objectives. While variables exist that could undermine the solidarity between the two countries due to China's perception and domestic/international issues within Japan, it is reasonable to expect that US-Japan solidarity will continue for the time being, prolonging China's difficulties.

References Austin, L. 2021. “Secretary of Defense Remarks at the 40th

International Institute for Strategic Studies Fullerton

Lecture”, Department of Defense. Available at:

https://www.defense.gov/News/Speeches/Speech/Article/270

8192/secretary-of-defense-remarks-at-the-40th-international-

institute-for-strategic/ [Accessed December 2023].

2021. “Secretary of Defense Remarks for the U.S.

INDOPACOM Change of Command”, Department of

Defense. Available at:

https://www.defense.gov/news/Speeches/Speech/Article/2592 31 1.US Integrated Deterrence Strategy and US-Japan Alliance_Sasebo JMSDF Historical Archives

093/secretary-of-defense-remarks-for-the-us-indopacom-

change-of-command/ [Accessed December 2023].

Chase, M.S. and Chan, A. 2016. “China's Evolving Approach to

"Integrated Strategic Deterrence"” RAND Corporation, RR-

1366-TI, pp. 1.

Department of Defense. 2023. “Data, Analytics, and Artificial

Intelligence Adoption Strategy” pp. 3.

Isobe, K. 2023. “Japan’s Perspective on Command and Control Issues in

the Japan-U.S. Alliance”, Center for Strategic and

International Studies. Available at:

https://www.csis.org/analysis/japans-perspective-command-

and-control-issues-japan-us-alliance [Accessed December

2023].

Jervis, R. 1979. “Deterrence Theory Revisited”, World Politics, 31(2),

pp. 289–324.

Kamphausen, R.D. 2023. “Modernizing deterrence – How China

coerces, compels and deters”, The National Bureau of Asian

Research.

32 Knopf, J.W. 2010. “The Fourth Wave in Deterrence Research”,

Contemporary Security Policy, 31(1), pp. 1-33. Lupovici, A. 2010. “The Emerging Fourth Wave of Deterrence

Theory—Toward a New Research Agenda”, International

Studies Quarterly, 54(3), pp. 705–732.

Manzo, V. 2011. “Deterrence and Escalation in Cross-Domain

Operations: Where Do Space and Cyberspace Fit?”, Strategic

Forum, National Defense University, December, pp. 2.

McInnis, K. 2022. “‘Integrated Deterrence’ Is Not So Bad'”, Center for

Strategic and International Studies. Available at:

https://www.csis.org/analysis/integrated-deterrence-not-so-

bad [Accessed October 2023].

Ministry of Defense of Japan 2022. “National Defense Strategy”.

Available at:

https://www.mod.go.jp/j/policy/agenda/guideline/strategy/pdf

/strategy_en.pdf [Accessed October 2023].

2023. “Defense Programs and Budget of Japan”, pp. 16.

2023. “The 2023 Defense of Japan (Annual White Paper)”,

pp. 15, 249, 281.

33 1. United States' “Integrated Deterrence” Strategy and the Japan-U.S. Alliance_Sasebo Naval Base Maritime Self-Defense Force Archives Ministry of Foreign Affairs of Japan. 2023. “Japan-U.S. Security

Consultative Committee (Japan-U.S. “2+2”)”, Ministry of

Foreign Affairs of Japan, Japan-United States of America

Relations. Available at:

https://www.mofa.go.jp/na/st/page4e_001338.html [Accessed

November 2023].

Monaghan, S. 2023. “Bad Idea: Integrated Deterrence as strategy”,

Defense360. Available at: https://defense360.csis.org/bad-

idea-integrated-deterrence-as-strategy/ [Accessed October

2023].

Moriyasu, K. & Takeuchi, Y. 2023. “Japan brings forward Tomahawk

acquisition by a year”, Nikkei Asia. Available at:

https://asia.nikkei.com/Politics/Defense/Japan-brings-

forward-Tomahawk-acquisition-by-a-year [Accessed January

2024].

Nakazawa, K. 2022. “Analysis: Xi ditched milder options in sending

missiles toward Japan”, Nikkei Asia. Available at:

https://asia.nikkei.com/Editor-s-Picks/China-up-

close/Analysis-Xi-ditched-milder-options-in-sending-

missiles-toward-Japan [Accessed January 2024].

34 Reuters. 2023. “Japan’s return to path of militarization ‘dangerous’ –

China defence ministry”, Reuters Asia Pacific. Available at:

https://www.reuters.com/world/asia-pacific/japans-return-

path-militarisation-dangerous-china-defence-ministry-2023-

03-16/ [Accessed January 2024].

Schelling, T.C. 1966. “Arms and Influence”, New Haven: Yale

University Press, pp. 146-148.

Scouras, J., Smyth, E., & Mahnken, T. 2017. “Cross-Domain Deterrence

in US–China Strategy”, Johns Hopkins Applied Physics

Laboratory, pp. 7.

Sisson, M.W. 2022, Nov. “There is a lot to like in the 2022 National

Defense Strategy”, Brookings. Available at:

https://www.brookings.edu/articles/there-is-a-lot-to-like-in-

the-2022-national-defense-strategy/ [Accessed October

2023].

Spencer, R. 2007. “Chinese missile destroys satellite in space”, The

Telegraph. Available at:

https://www.telegraph.co.uk/news/worldnews/1539948/Chine

se-missile-destroys-satellite-in-space.html [Accessed January

2024].

35 1. U.S. “Integrated Deterrence” Strategy and the U.S.-Japan Alliance_Sasebo Naval Base Historical Archives Spoehr, T. 2021. “Bad Idea: Relying on ‘Integrated Deterrence” Instead

of Building Sufficient U.S. Military Power”, The Heritage

Foundation. Available at:

https://www.heritage.org/defense/commentary/bad-idea-

relying-integrated-deterrence-instead-building-sufficient-us-

military [Accessed January 2024].

Takahashi, K. 2023. 'Poll: Japanese Support for Self-Defense Forces

Rises to Record High', The Diplomat. Available at:

https://thediplomat.com/2023/03/poll-japanese-support-for-

self-defense-forces-rises-to-record-high/ [Accessed January

2024].

THE ASAHI SHIMBUN, 2023. 'Japan, U.S. go all in on Tokyo’s

counterstrike capability', The Asahi Shimbun. Available at:

https://www.asahi.com/ajw/articles/14812666 [Accessed

January 2024].

Tucker, P. 2023. 'US to deploy new land-based missiles, Army’s Pacific

commander says', Defense One. Available at:

https://www.defenseone.com/technology/2023/11/us-deploy-

new-land-based-missiles-armys-pacific-commander-

says/392137/ [Accessed January 2024].

36 U.S. Mission Japan. 2023. 'Joint Statement of the Security Consultative

Committee (2+2)', U.S. Embassy & Consulates in Japan,

Speeches & Statements. Available at:

https://jp.usembassy.gov/joint-statement-security-

consultative-committee-2plus2/ [Accessed October 2023]. Watanabe, T. 2023. 'What’s New in Japan’s Three Strategic

Documents', Center for Strategic and International Studies,

Experts. Available at: https://www.csis.org/analysis/whats-

new-japans-three-strategic-documents [Accessed December

2023].

Zhang, H. .2023. 'US potential intermediate-range missiles deployment

‘big provocation’ to China', Global Times. Available at:

https://www.globaltimes.cn/page/202311/1302569.shtml

[Accessed January 2024].

Kim Yang-gyu 2024. "New Year Special Commentary Series] ③ The Global Military Order in 2024

and Korea: Offensive Advantage Following the Revolution in Precision and Transparency

Korea's Security Policy in the Era of Transition," East Asia Institute. Available

at:https://www.eai.or.kr/new/ko/pub/view.asp?intSeq=

22294&board=kor_issuebriefing%27,%27kor_workingpa 37 1. U.S. "Integrated Deterrence" Strategy and the U.S.-Japan Alliance_Sasebo Maritime Self-Defense Force Archives

per%27,%27kor_special%27,%27kor_multimedia&keywo

rd_option=&keyword=&more= [Accessed January 2024]. Republic of Korea Ministry of National Defense 2023. 55th ROK-U.S. Security Consultative Meeting (SCM) Joint Communiqué,

Republic of Korea Ministry of National Defense. Available at:

https://www.mnd.go.kr/user/newsInUserRecord.action?s

iteId=mnd&page=1&newsId=I_669&newsSeq=I_13495&

command=view&id=mnd_020500000000&findStartDate

=&findEndDate=&findType=title&findWord=&findOrga

nSeq= [Accessed December 2023]. Liberal Democratic Party Policy Research Council.

2020. "Proposals for Enhancing Deterrence to Protect the Nation",

"Liberal Democratic Party".

House of Councillors. 1999. "145th Session (Ordinary Session) Written Questions and Answers", Top, Written Questions

and Answers. Available at:

https://www.sangiin.go.jp/japanese/joho1/kousei/syuisyo

o/145/touh/t145022.htm (Accessed: November 2023). Xinhua Net 2022. "(Authorized Release) Xi Jinping: Hold High the Great Banner of Socialism with Chinese Characteristics

and Strive in Unity to Build a Modern Socialist Country in All Respects - Report at the 20th National Congress of the Communist Party of China",

Available

at: http://www.news.cn/politics/cpc20/2022-

38 10/25/c_1129079429.htm [Accessed January

2024].

Yuan Yi, Li Zhifei 2022. "Military Forum | Adhere to the Integrated Development of Mechanization, Informatization, and Intelligentization",

China Military Online - PLA Daily. Military Academy of Strategic Studies, Chinese People's Liberation Army

2020. "Strategic Studies", pp. 136.

39