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Razade Permadi Wicaksono Mahasiswa Universitas Kristen Indonesia razadepermadi@gmail.com Abstract Japan’s defensive posture in 2025 is defined by the challenge of adapting to an increasingly contested missile age. Confronted with North Korea’s accelerating missile programs, China and Russia’s expanding strategic strike and naval capabilities and constant territorial incursions, Tokyo has embarked on a historic defense recalibration. This paper examines how Japan’s evolving security strategy reflects both necessity and restraint within the framework of the security dilemma. It highlights four central pillars of Japan’s current trajectory. The first action is the institutionalization of Integrated Air and Missile Defense (IAMD). The second is the acquisition of stand-off and counterstrike capabilities. The third course of action is through deeper alliance integration and multilateral security diplomacy, and the revitalization of the defense industry alongside economic security reforms. Whilst these developments strengthen deterrence and alliance credibility, they also expose Japan to domestic and regional constraints, including pacifist sentiment, budgetary limits, and perceptions of rearmament. The analysis identifies three potential trajectories, that is assertive modernization, constrained rollback, and calibrated evolution, arguing that the latter is most likely, given budgetary trends and policy statements. The article concludes that Japan’s future posture will depend on balancing deterrence with transparency, sustaining domestic legitimacy, and embedding modernization within broader confidence-building measures. In so doing, Tokyo positions itself not as a destabilizing power, but as a stabilizing anchor in the Indo-Pacific security architecture. The Surrounding Situation and the Strategic Background Beginning in the early 21st century, the developing security environment surrounding Japan has left the nation with a considerable burden of security dilemma. Technological advancement and constant airspace and maritime territorial violations by China and Russia, followed by continuous ballistic missile tests conducted and North Korea have compressed decision times and raised the stakes of territorial contingencies (JMOD, 2023). Japan is under prolonged contemplation regarding the capability of existing defensive assets in answering the state-of-the-art threats of aforementioned nations. In 2022, Tokyo issued its National Security Strategy (NSS), followed by 2023 Defense of Japan white papers which explicitly frame this new environment as the rationale for deeper deterrence investments and broader defense diplomacy. The NSS calls for “comprehensive national power” mobilization across diplomacy, defence, and economic security, while the MOD documents catalog expanded A2/AD challenges and ballistic/hypersonic threats (Cabinet Secretariat, 2022; JMOD, 2023). Based on these official explanations, Japan’s rapid defense recalibration in 2025 must be read against a sharply changed regional security environment. Concretely, Tokyo has translated strategy into resources and capability shifts. The government approved record defense budgets at the end of 2024 and is pursuing accelerated procurements, most notably agreements to acquire U.S. long-range strike munitions, expansion of integrated air-and-missile-defense (IAMD) capabilities, increasing research and development of domestic stand-off capabilities, and space based assets measures Tokyo’s approach in its defensive adaptations to the “missile age” (Arthur, 2025). Politically, these moves reflect a careful balance by strengthening credible deterrence while attempting to reassure neighbours and manage domestic legal and public-opinion constraints. In short, Japan’s 2025 posture is an evolutionary response to compressed threat environments and technological change, not an abrupt repudiation of its postwar defensive orientation. Theoretical Framework: Security Dilemma and the Missile Age Japan’s tremendous trajectory to attain ‘proactive defense’ posture and stand-off capabilities cannot be divorced from the broader analytical lens of the security dilemma. In realist international relations theory, the security dilemma posits that one state’s efforts to enhance its security, through the means of acquiring advanced defense systems for example, may be perceived by others as offensive in nature, thereby prompting countermeasures and potentially exacerbating regional insecurity (Jervis, 1978). This theoretical framework is particularly relevant in East Asia, where historical grievances, contested sovereignty, and enduring mistrust compound the effects of military modernization. The rise of the missile age has sharpened this dilemma. Ballistic missiles, cruise missiles, and hypersonic missiles, due to their speed, precision, and potential for carrying both conventional and nuclear payloads, compress decision-making timelines and increase the risks of miscalculation (Acton, 2013). For Japan, the North Korean missile threat represents the immediate and tangible justification for BMD acquisition, with Pyongyang’s repeated launches over or near Japanese territory underscoring Tokyo’s vulnerability (JMOD, 2023). Yet Japan’s layered BMD cooperation with the United States, particularly the integration of AEGIS destroyers, SM-3 interceptors, and upcoming SM-6 capabilities viewed by China as part of a broader U.S.-Japan containment strategy. The dilemma is further compounded by the dual-use nature of missile defense systems. While Japan emphasizes its BMD as purely defensive, the potential to pair interceptors with stand-off strike capabilities (such as the planned acquisition of Tomahawk missiles and domestic Type-12 upgrades) blurs the boundary between defense and offense (Sakaki, 2023). Yet, these potentials were addressed by Japan as a necessity and would be used exclusively for defensive purposes. In this context, the security dilemma framework highlights two critical dimensions of Japan’s defensive posture evolution: Assurance and deterrence for domestic and allied audiences, where increased defensive capacity reduces vulnerability and strengthens the credibility of U.S. and allied extended deterrence. Perceptions of encirclement and escalation by regional rivals, where the same systems risk entrenching strategic competition. By situating Japan’s BMD development within the interplay of the security dilemma and the missile age, this article underscores the dual-edged consequences of Tokyo’s defense modernization. What enhances deterrence against one adversary may simultaneously erode stability with another. Core Pillars of Japan’s Evolving Defensive Posture Integrated Air and Missile Defense (IAMD) Japan’s strategic environment, defined by North Korea’s evolving missile force and China’s expanding precision-strike arsenal, has accelerated Tokyo’s transition from a layered ballistic missile defense (BMD) model toward a fully Integrated Air and Missile Defense (IAMD) architecture. The 2022 National Security Strategy and Defense Buildup Program explicitly prioritize IAMD, underscoring the need to merge early-warning, tracking, and engagement systems across air, sea, land, cyber, and space domains (Cabinet Secretariat, 2022; JMOD, 2023). Operationally, Japan is enhancing the Japan Aerospace Defense Ground Environment (JADGE) to synchronize with the Japanese constellation of intelligence satellites, U.S. early warning satellites, existing AEGIS-equipped destroyers, land-based Patriot PAC-3 MSEs, and the forthcoming Aegis System Equipped Vessels (ASEV), creating a distributed yet unified engagement network (JMOD, 2024). This shift reflects recognition that isolated BMD layers are insufficient against saturation strikes and hypersonic glide vehicles (HGV). Through the strategic telescope, IAMD provides resilience and reinforces deterrence by denial, while also reassuring the U.S. that Japan is committed to burden-sharing in the missile defense mission. However, success hinges on seamless interoperability, real-time data fusion, and political clarity on command authority during crises. These factors will determine whether IAMD becomes a stabilizing deterrent mechanism or a fragile patchwork vulnerable to exploitation. Stand-off and Counterstrike Capabilities Japan’s acquisition of stand-off and counterstrike capabilities marks the most significant departure from its traditional “exclusively defense-oriented policy” since the Cold War. The 2022 National Security Strategy authorized the Self-Defense Forces (SDF) to conduct counterstrike operations, primarily to neutralize imminent missile threats (Cabinet Secretariat, 2022). This doctrinal shift is operationalized through procurement of U.S. made Tomahawk cruise missiles, and upgrades to the indigenous Type-12 surface-to-ship missile for extended range and land-strike capabilities (MOD, 2023). Additionally, the development of Hyper Velocity Gliding Projectile (HGVP) symbolizes Tokyo’s own answer in the race of global hypersonic weapons capability. The HGVP, which according to Inaba (2024) was being developed for island defense roles, has been expedited to enter service as early as 2026. The Aegis-system Equipped Vessel (ASEV) would also be the primary example of such a strategy. Primarily built for ballistic missile defense (BMD) mission after the cancellation of land-based Aegis Ashore system, the ship type, which would naturally give higher operational flexibility than its land based counterpart, has been plotted to be equipped with stand-off capabilities such as Tomahawks cruise missiles and upgraded Type 12, with plans for installation at least by 2032 (JMOD, 2024). Strategically, stand-off capabilities expand Japan’s deterrence by denial, complicating adversary planning by threatening high-value nodes such as missile launchers and command centers. Nevertheless, the policy carries risks. Alliance Integration and Multilateral Security Diplomacy Alliance integration remains the cornerstone of Japan’s defense evolution in the missile age, of which Tokyo has expanded its strategy beyond the U.S. - Japan bilateral framework toward a networked multilateral security posture in the region. At the alliance core, deeper interoperability with U.S. forces, ranging from Tomahawk procurement to SM-6 missile integration, anchors deterrence through shared command, control, and sensor fusion (DSCA, 2023; DSCA; 2025). Despite the primary strategy centralized around the U.S. - Japan alliance, Japan has also globalized its defense diplomacy. With revisions made to The Three Principles on Transfer of Defense Equipment and Technology, Japan has emerged as a key player in defense equipment in the Indo-Pacific Region. The following steps have led to significant success of Tokyo’s proactive approach in defense diplomacy in the Indo-Pacific region. The transfer of FPS-3/ME air surveillance radars to the Philippines strengthens Manila’s domain awareness and demonstrates Japan’s role as a net security provider in Southeast Asia (Takei, 2024). Similarly, defense-industrial cooperation with Australia, including discussions of improved Mogami-class frigates, resulted in the decision of the Australian government to procure the specified class as their next-generation warship to replace the aging Anzac-class frigates (Australia MOD, 2025). Interoperability with allies and like-minded nations also played a considerable part in strengthening Japan's defensive posture. As a part of Royal Navy’s ‘Operation Highmast’, Japan, alongside the United Kingdom and the U.S. conducted a series of crossdeck carrier flight operations for the first time in history. Two Royal Navy’s F-35Bs alongside two USMC’s F-35Bs conducted landing and take-off exercises aboard Japan’s recently upgraded Izumo-class multipurpose destroyer JS Kaga (DDH-184) (Mahadzir, 2025). The 9-day exercise signalled a strong combined cross-nations interoperability in the Indo-Pacific region Defense Industry, Tech & Economic Security Japan’s defense transformation is inseparable from its efforts to revitalize its defense industrial base and secure strategic technologies. The 2022 Defense Buildup Program emphasizes accelerating research and production capacity in missile defense, stand-off weapons, and next-generation fighters, while facilitating joint development projects with allies such as the Global Combat Air Programme (GCAP) with the U.K. and Italy (MOD, 2023). Beyond weapons systems, Tokyo identifies economic security as a defense priority. In May 2022, Japan enacted the Economic Security Promotion Act, which mandates strengthened resilience in supply chains for critical sectors (e.g., semiconductors, critical minerals) and the development of specified critical technologies (METI, 2023). These measures not only bolster Japan’s self-reliance but also enable it to function as a stable technology partner within alliance frameworks. However, Japan faces structural hurdles. A limited domestic arms market, workforce shortages, and political sensitivities over arms exports. Addressing these challenges will determine whether Tokyo can sustain its ambitious buildup while avoiding overdependence on foreign suppliers. Risks, Constraints, & Balancing Acts Japan’s defense transformation faces significant domestic political constraints. While polls show growing concern over regional threats, public opinion remains divided over constitutional revision and the rapid pace of defense budget increases (Mainichi, 2023). Pacifist sentiment and sensitivity to “rearmament” narratives restrict how far Tokyo can push its counterstrike doctrine without provoking political backlash Fiscal limits also remain binding, that is to sustain an unprecedented pledge to raise defense spending to 2% of GDP by 2027 strains Japan’s debt-laden economy. Externally, Japan’s assertive posture risks regional backlash. China has framed Tokyo’s counterstrike acquisition as “militaristic resurgence,” while North Korea has intensified missile tests to contest Japan’s missile defense initiatives (MOFA, 2023). Such responses increase escalation risks and fuel propaganda that could erode Japan’s regional credibility. At the alliance level, frictions may emerge. Washington expects faster integration of Japanese assets into Indo-Pacific strategy, but domestic politics complicate basing decisions and technology transfers. Divergences in burden-sharing or operational doctrine could generate misalignment. To mitigate these risks, Tokyo should pursue confidence-building measures. Several of such mitigations are to materialize transparent procurement timelines, expanded arms control dialogues with regional actors, and phased introduction of sensitive capabilities. These measures would balance deterrence signaling with reassurance, sustaining domestic legitimacy and regional stability. Conclusion Japan’s evolving security trajectory reflects a delicate balance between capability enhancement, alliance management, and domestic legitimacy. The gradual acquisition of stand-off strike systems, integration into IAMD frameworks, and reinforcement of defense industrial resilience signal a decisive shift away from traditional postwar constraints. Yet, these measures remain embedded within Japan’s alliance-centered security architecture and calibrated to avoid outright arms racing. Looking forward, Japan’s challenge lies in harmonizing its defense modernization with domestic consensus, economic sustainability, and credible reassurance to regional actors. If Tokyo manages to balance between linking transparency, industrial revitalization, and steady capability growth, it will not only strengthen deterrence but also position itself as a stabilizing anchor in an increasingly contested Indo-Pacific order. References Acton, J. M. (2013). Silver Bullet? Asking the Right Questions About The Conventional Prompt Global Strike. Carnegie Endowment for International Peace. https://carnegie-production-assets.s3.amazonaws.com/static/files/cpgs.pdf Arthur, G. (2025, January 16). Japan Passes Record Defense Budget, While Still Playing Catch-Up. Defense News. https://www.defensenews.com/global/asia-pacific/2025/01/16/japans-passes-record-defense-budget-while-still-playing-catch-up/Australia MOD. (2025, August 5). Mogami-class frigate selected for the Navy’s new general purpose frigates. Defence Ministers; Australia Ministry of Defence. https://www.minister.defence.gov.au/media-releases/2025-08-05/mogami- class-frigate-selected-navys-new-general-purpose-frigates Cabinet Secretariat. (2022). National Security Strategy of Japan. https://www.cas.go.jp/jp/siryou/221216anzenhoshou/nss-e.pdf DSCA. (2023, November 17). Japan - Tomahawk Weapon System. Defense Security Cooperation Agency. https://media.defense.gov/2024/Dec/12/2003610554/-1/-1/0/PRESS%20R ELEASE%20-%20JAPAN%2023-69%20CN.PDF DSCA. (2025, January 31). Japan – Standard Missile 6 (SM-6) Block I Missiles. Defense Security Cooperation Agency. https://www.dsca.mil/Press-Media/Major-Arms-Sales/Article-Display/Arti cle/4049967/japan-standard-missile-6-sm-6-block-i-missiles Inaba, Y. (2024, July 8). Video: Japan tests Hyper Velocity Gliding Projectile - HVGP . Naval News. https://www.navalnews.com/naval-news/2024/07/video-japan-tests-hyper- velocity-gliding-projectile-hvgp/ Jervis, R. (1978). Cooperation Under The Security Dilemma. World Politics, 30(2), 167–214. https://doi.org/10.2307/2009958 JMOD. (2023). Defense of Japan 2023 White Paper. Japan Ministry of Defense. https://www.mod.go.jp/en/publ/w_paper/wp_2023.html JMOD. (2024). Defense of Japan 2024 White Paper. Japan Ministry of Defense. https://www.mod.go.jp/en/publ/w_paper/wp2024/DOJ2024_EN_Full.pdf Mahadzir, D. (2025, August 13). VIDEO: U.K., U.S. F-35B Fighters Land, Launch from Japan’s Largest Warship. USNI News. https://news.usni.org/2025/08/13/video-u-k-u-s-f-35b-fighters-land-launch-from-japans-largest-warship METI. (2023). Japan Economic Security Promotion Act. Japan Ministry of Economy, Trade, and Industry. https://www.meti.go.jp/english/report/data/wp2023/pdf/2-1-2.pdf Sakaki, A. (2023, March 3). The Historic Decision on Military Armament. Stiftung Wissenschaft Und Politik. https://www.swp-berlin.org/10.18449/2023C13/ Takei, T. (2024). Provision of Radars to the Philippines Can Create a 3,000-Nautical-Mile Air Surveillance Zone | List of Articles | International Information Network Analysis | SPF. International Information Network Analysis; Sasakawa Peace Foundation. https://www.spf.org/iina/en/articles/tomohisa_takei_01.html The Mainichi. (2024, May 3). 27% in Japan in favor of constitutional revision, 52% against: Mainichi poll. The Mainichi. https://mainichi.jp/english/articles/20240503/p2a/00m/0na/007000c

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