The Ripple Effects of Japan's Defense White Paper and China-Japan Security Tensions: Situational Analysis Ahead of the December Revision of the Three Security Documents

Executive Summary

Japan's 2026 Defense White Paper is a document that reconfirms the fourth-year implementation status of the trajectory of defense spending increases and acquisition of counterstrike capabilities set by the 2022 revision of the three security documents, and it triggered a stronger backlash than in previous years as its timing overlapped with China's expanding presence in the Western Pacific. China lodged protests sequentially through both its Ministry of Foreign Affairs and Ministry of National Defense channels, and North Korea immediately cited and reported this, riding on the propaganda campaign to counter US-Japan-South Korea cooperation, showing a pattern in which the conflict spread to the broader Northeast Asian security architecture. With the Takaichi cabinet's constitutional revision and military buildup line having become fixed as a domestic political identity, the re-revision of the three security documents in December is expected to be the next watershed in this conflict cycle. Premised on a base scenario (55% probability) in which rhetorical clashes repeat through the end of the year while a complete rupture is avoided, a strategy is required that tracks in real time the two variables—the level of specificity of Taiwan-related language and the intensity of China's response—and adjusts the response level in stages accordingly. South Korea needs to recognize this conflict not as a matter to be observed from the sidelines but as a matter of direct interest, and to move to inspect vulnerable points in its supply chains and to secure advance information through Korea-Japan and Korea-China channels.

I. Issue Situation Analysis

Escalation of China-Japan Security Tensions Triggered by Japan's Defense White Paper: Situational Analysis

1. Background and Development

The Japanese government approved the 2026 edition of the Defense White Paper at a cabinet meeting on August 4. The 610-page document once again designated China as "the greatest strategic challenge of unprecedented scale" [17]. This phrase itself is not new; it repeats language first adopted in the 2022 revised National Security Strategy [12]. However, this year's white paper differs from previous editions in that its description of China's Taiwan issue has become considerably more explicit, and it specifically identifies China's movements to expand into the Pacific beyond the First Island Chain [12].

Japan's shift in security policy has already been set on track since the December 2022 revision of the three security documents. The National Security Strategy, National Defense Strategy, and Defense Buildup Program revised at that time presented three pillars: strengthening comprehensive national power encompassing diplomatic, defense, economic, technological, and intelligence capabilities; deepening the US-Japan alliance and solidarity with like-minded countries; and expanding integrated deterrence [2]. An EAI report commented on this, noting that it "also resembles a Japanese version of the U.S. National Security Strategy (NSS) published last October" [2]. The core elements were the goal of increasing defense spending to 2% of GDP by 2027, the acquisition of counterstrike capabilities (the capability to strike enemy bases), and integrated deterrence investment in the cyber, space, and electromagnetic domains [2]. The 2026 Defense White Paper should be understood as a document that, in extension of the trajectory set by these three documents, once again publicly announces the implementation status now in its fourth year.

The political context cannot be ignored either. The Takaichi Sanae cabinet has simultaneously pursued constitutional revision and military buildup, and on May 19, a citizens' rally opposing this was held in front of the National Diet Building in Tokyo [10]. Although the Defense White Paper features an anime-style futuristic city image on its cover, local progressive commentary views its content as containing an even more hawkish security agenda, including long-range missiles, counterstrike capabilities, and strengthened cooperation between the military and private technology companies [10].

2. Current Situation

China's backlash came sequentially through both the Ministry of Foreign Affairs and the Ministry of National Defense. A Ministry of National Defense spokesperson responded immediately on August 4, the day the white paper was released, and Ministry of Foreign Affairs spokesperson Lin Jian raised a "serious diplomatic protest" on August 5 [5]. The Ministry of Foreign Affairs characterized the white paper as "repeating baseless accusations, rehashing the so-called China threat theory, and seriously interfering in China's internal affairs through blatant references to the Taiwan issue" [5]. China's state media outlet Global Times highlighted the gap between the white paper's cover image and its actual content, framing its coverage around the notion of a "false narrative" [10].

North Korea also spoke up, riding on this conflict. Between August 5 and 8, the Korean Central News Agency and Rodong Sinmun successively cited and reported on the critical statements against Japan issued by China's Ministry of National Defense and Ministry of Foreign Affairs. Rodong Sinmun, citing the Chinese Ministry of National Defense's statement, reported that Japan's white paper was "nothing but a case of a thief brandishing a club, seeking a pretext to break free from military restraints" [1][8]. It then reprinted verbatim, citing the Chinese Ministry of Foreign Affairs's statement, the assessment that "Japanese militarism brought enormous disaster to Asia and the world and committed innumerable crimes, yet Japan has not seriously reflected on its history" [14][15]. North Korea's choice to report by citing China's statements rather than offering its own commentary can be read as an attitude of aligning with China in criticizing Japan while, rather than staking out an independent confrontational position, consuming this issue within the existing framework of the US-Japan-South Korea trilateral threat theory [9].

The perspective of Western and regional media differs from this. The Diplomat focused on the fact that the white paper cited China's strengthening of its aircraft carrier forces and expansion of its far-seas operational capabilities in the Western Pacific as grounds [17][12], while the South China Morning Post instead focused on the anxiety among Chinese strategists. The analysis is that Defense Minister Koizumi Shinjiro's acknowledgment of a "defense gap" in the Pacific region is perceived in Beijing as a signal that the U.S. security umbrella is structurally loosening, and that this is forming a "corrosive security dilemma" that in turn provides logic to justify Japan's own military buildup [16].

3. Key Actors and Positions

The Japanese Governmenthas a dual purpose through the Defense White Paper: externally, to send a warning signal about China's military expansion, and internally, to reaffirm the legitimacy of the defense spending increase and acquisition of counterstrike capabilities under the three security documents. For the Takaichi cabinet, formalizing its perception of the China threat is also necessary to sustain momentum for constitutional revision [10]. However, the fact that opposition to the military buildup line clearly exists at the civil society level within Japan [10] suggests that the government's hardline stance toward China has not achieved full domestic consensus.

The Chinese Governmenthas expressed intense protest through the dual channels of the Ministry of Foreign Affairs and the Ministry of National Defense, while constructing its protest logic along two lines. The Ministry of National Defense employed a security frame, characterizing the white paper as an act of seeking "a pretext to break free from military restraints" [1], while the Ministry of Foreign Affairs mobilized a historical and normative frame centered on Japan's lack of historical reflection and remilitarization [14]. According to EAI analysis, China's approach toward Japan and South Korea operates as a subordinate variable of its strategy toward the United States. China perceives the formation of anti-China sentiment in South Korea and Japan, which provides a pretext for the U.S.-led strengthening of trilateral security cooperation among South Korea, Japan, and the U.S., as a security dilemma, and the incentive to stably manage relations with South Korea and Japan grows greater as conflict with the United States intensifies, in order to prevent this [11].

North Korearode on this phase by reporting China's criticism of Japan through citation rather than through its own independent commentary [1][8][14][15]. This is an extension of the existing frame Chairman Kim Jong Un has maintained since the end of 2022, namely, the perception of a "new Cold War" that defines and treats the US-Japan-South Korea trilateral cooperation as an "Asian version of NATO" [9].

The United Statesdid not emerge as a direct party to this conflict, but it is a structural actor in that the U.S. Indo-Pacific strategy underlies the increase in Japan's defense spending and its integrated deterrence strategy. Eurasia Group, in its 2026 geopolitical risk outlook, assessed that direct conflict between the U.S. and China is not the top-tier risk [3], which connects with the South China Morning Post's analysis that, amid a structure of managed competition between the U.S. and China, allies such as Japan have an incentive to more actively fill security gaps themselves [16].

South Koreais not a direct party to this issue, but there is precedent of strategic divergence between South Korea and Japan over the level of engagement with the US-Japan alliance in the event of a Taiwan contingency [4]. In that the possibility cannot be excluded that China's pressure on Japan could spill over into a similar form toward South Korea in the future, South Korea qualifies as an indirect stakeholder.

4. Key Issues

The first issue is the question of coherence between Japan's security document architecture and its threat perception of China. The process by which the perception of China set out in the 2022 three security documents becomes further specified in the 2026 white paper, extending even to the Taiwan issue, illustrates the recurring structure of policy confirmation and reinforcement that exists between the timing of document revision (year-end) and the timing of white paper release (August). If a review or revision of the three security documents is indeed scheduled for year-end, the level of description regarding China contained in this white paper is highly likely to function as a leading indicator of its direction.

The second issue is whether China's protest is a means to pressure for substantive policy change or merely a ceremonial response for the purpose of managing domestic and international opinion. The dual-channel statement system of the Ministry of Foreign Affairs and Ministry of National Defense, along with the remobilization of the historical frame, is a pattern that has been repeated in similar past cases, and the key question is whether this will actually lead to economic or diplomatic retaliatory measures.

The third issue is the gap in perception surrounding the credibility of the US-Japan security umbrella. The future intensity of China's response may vary depending on whether China interprets the emergence of debate within Japan over a Pacific defense gap as a crack in the U.S. alliance system, or merely as a pretext for Japan's autonomous military expansion [16].

The fourth issue is the nature of the North Korea variable. Whether the current pattern of North Korea merely citing Chinese statements rather than taking independent action will continue, or whether it will lead to a separate military demonstration in response to the deepening of US-Japan-South Korea cooperation, is a variable that will determine the pace of intensification of the Northeast Asian security dilemma.

II. In-Depth Issue Analysis

Escalation of China-Japan Security Tensions Triggered by Japan's Defense White Paper: In-Depth Analysis

1. Root Cause: A Structure Where Two Timelines Collide

The superficial trigger for this conflict is a single annual document, the Defense White Paper. However, there is a separate reason why a single document has provoked such a strong reaction. It is because the implementation timeline set by the three security documents revised in December 2022 and another timeline—China's expanding presence in the Western Pacific—collided head-on at the point of 2026.

Japan's three security documents fixed the goal of increasing defense spending to 2% of GDP by 2027 [2]. 2026 is the year one year before the deadline for achieving this goal. It coincides with the point at which the buildup of counterstrike capabilities, the introduction of long-range strike systems, and the construction of integrated deterrence enter the stage of actual force deployment [2]. The fact that the Defense White Paper has become bulkier than in previous years at "610 pages" and prominently features long-range attack capabilities and new operational methods [15] indicates that the revision of the document itself is less a new phase than a procedure to reconfirm the implementation status of an already-set trajectory.

During the same period, China has been strengthening its aircraft carrier forces and building up its capacity for sustained operations in the Western Pacific beyond the First Island Chain [17]. Japan's Ministry of Defense has characterized this using the expression "Pacific defense gap," and Defense Minister Koizumi Shinjiro has hinted at a perception to the effect that Japan is filling a gap left by the United States [16]. In other words, in Japan's logic, China's push into the far seas is the cause and Japan's military buildup is the response, but in China's logic, Japan has already fabricated in advance "a pretext to break free from military restraints" and is redefining China's normal military activities as a threat to fit that pretext [1]. This self-reinforcing structure, in which the two timelines each justify themselves by reference to the other, is the root cause of this conflict.

2. Structural Context

2-1. Political Structure: The Takaichi Cabinet's Domestic Base and the Constitutional Revision Timeline

The Takaichi Sanae cabinet has taken the line of simultaneously pursuing constitutional revision and military buildup [10]. Domestic backlash against this line has already become visible. The rally in front of the National Diet Building in Tokyo on May 19 gathered citizens opposing the attempt at constitutional revision and the military buildup measures [10]. The gap between the Defense White Paper's cover, decorated with an anime-style futuristic city image, and its main text, which emphasizes long-range missiles, counterstrike capabilities, and military-private technology company cooperation, is a point that Chinese state media attacks as a "false narrative" [10], and at the same time can be read as a trace of the Japanese cabinet attempting to manage the document's external impression out of consciousness of domestic public backlash.

In this domestic political structure, the Defense White Paper approaches a political ritual that annually reconfirms the cabinet's security line. China's strong backlash may actually be used as grounds to domestically legitimize this ritual. It is a circular structure in which the perception of security threats reinforces the justification for increasing defense spending and pursuing constitutional revision.

2-2. Security Structure: The Problem of US-Japan Alliance Credibility and the Demand for Autonomous Defense

A South China Morning Post commentary evaluates this white paper as a case confirming a situation that Chinese strategists have been concerned about, namely that the postwar pacifist constraints are being dismantled under the pretext of "self-defense" [16]. What is interesting is the paradox this commentary points out. The circumstance in which Japan has concluded that the U.S. security umbrella is structurally flimsy is, from Beijing's standpoint, received as a warning about the vulnerability of the alliance itself, while simultaneously heightening anxiety over the resurgence of Japan as an autonomous military power [16]. In other words, China is placed in a dual dilemma in which it must be wary both of the weakening of the US-Japan alliance and of Japan filling the alliance's gap on its own and strengthening its independent deterrent capability.

This structure also ripples into South Korea-Japan relations. South Korean security academia has pointed out the possibility that South Korea's and Japan's responses could structurally diverge in the event of a Taiwan contingency [4]. While Japan has gone so far as to directly specify the Taiwan issue in its Defense White Paper, there is a difference in position in that South Korea must maintain strategic ambiguity on this issue [4]. As the China-Japan conflict intensifies, South Korea is placed in a structure where it is forced to choose between the pressure to adjust the intensity of US-Japan-South Korea cooperation and the separate calculus of managing relations with China.

2-3. Economic and Diplomatic Structure: Collision with China's Neighboring Diplomacy Priorities

According to EAI analysis, China's approach to South Korea-Japan-China cooperation is positioned as a subordinate strategy within China's diplomacy toward the United States [11]. The reason China places importance on the stability of neighboring regions is that its priority task is "maintaining the stability of East Asia, a neighboring region that could directly affect the stability of its own system" [11]. EAI's assessment is that China itself recognizes, in particular, "the necessity of preventing a situation in which China faces a security dilemma as anti-China sentiment forms in neighboring countries such as South Korea and Japan, providing a pretext for the U.S.-led strengthening of trilateral security cooperation among South Korea, Japan, and the U.S." [11]. Viewed from this structure, China's hardline response this time is less an attempt to weaken Japan's grounds for pressuring China than a defensive protest aimed at preventing the further consolidation of US-Japan-South Korea security cooperation. However, there is also the simultaneous risk that the intensity of the protest could produce the counterproductive effect of inflaming hardline anti-China sentiment within Japan.

3. Comparison with Historical Precedents

3-1. Continuity with the 2010 National Defense Program Guidelines

This is not the first time Japan has explicitly designated China as a threat in a security document. At the time of the 2010 revision of the National Defense Program Guidelines as well, Japan shifted from the Cold War-era posture centered on the Soviet Union to a security strategy responding to China's military rise [13]. An EAI commentary at the time characterized the National Defense Program Guidelines as "the top-level official document within Japan specifying under what objectives and how the Japan Self-Defense Forces would be operated, and further expressing Japan's security strategy" [13]. The 2026 Defense White Paper controversy shows that the standing of this document system has been maintained even 16 years later. However, what differs from 2010 is that, rather than a single document called the National Defense Program Guidelines, the system is now subdivided into three documents—the National Security Strategy, the National Defense Strategy, and the Defense Buildup Program—and EAI's observation is that this system follows the structure of the U.S. National Security Strategy (NSS) document [2].

3-2. Similarity to China's Reaction to the 2023 Trilateral Summit among South Korea, the U.S., and Japan

There was also a precedent in 2023 in which China strongly opposed a move to strengthen security cooperation. When the leaders of South Korea, the U.S., and Japan condemned China's coercive behavior in the South China Sea and agreed to strengthen military cooperation, Beijing lodged strong criticism [7]. The manner in which China's Ministry of Foreign Affairs and Ministry of National Defense issued sequential protest statements in this Defense White Paper conflict can be said to be a repetition of this precedent. However, the intensity differs in that the Taiwan issue was directly mentioned this time. China's elevation of the level of protest to the dual channel of the Ministry of Foreign Affairs and Ministry of National Defense is the typical response pattern that appears when the Taiwan issue is involved.

3-3. North Korea's Pattern of Riding the Wave

The manner in which North Korea speaks up by riding on the China-Japan conflict is also not a new phenomenon. North Korea had already, at the end of 2022, at the Workers' Party plenary meeting, framed and treated US-Japan-South Korea cooperation as a "new Cold War" [9]. The fact that Rodong Sinmun and the Korean Central News Agency successively cited and reported China's critical statements against Japan this time [1][8][14][15] is a familiar pattern in which North Korea incorporates the China-Japan conflict into the framework of US-Japan-South Korea versus China-North Korea-Russia, using it to reinforce its own new Cold War discourse. The fact that North Korean media reprinted verbatim the expression "like a thief brandishing a club" while citing the Chinese Ministry of National Defense's statement [1][8], and repeatedly reported the historical frame of "Japanese militarism" from the Ministry of Foreign Affairs statement [14][15], should be understood not as independent criticism of Japan but as an intent to check US-Japan-South Korea cooperation by borrowing China's logic.

4. Key Variables in the Development of the Issue

First, the level of specificity of the Taiwan issue references. The reason this white paper differs from previous ones lies in the blatancy of its Taiwan-related descriptions [5]. Whether Japan maintains this level going forward, or moderates its language for the sake of diplomatic management, becomes a variable determining the intensity of China's response.

Second, whether the three security documents are revised at year-end. China's Ministry of National Defense has already taken issue with Japan's document revision moves themselves, using the expression that Japan is "rushing to revise the three security-related documents" [1]. If the National Security Strategy and other documents are further revised around year-end with a strengthened stance of checking China, this Defense White Paper conflict is likely to solidify not as an isolated friction but as the first stage of a chain of conflicts.

Third, the direction of domestic public opinion in Japan. Whether the opposition sentiment expressed at the May rally spreads, or whether China's hardline protest conversely rallies pro-security-strengthening opinion within Japan, will determine the scope of policy maneuver available to the Takaichi cabinet [10].

Fourth, changes in China's assessment of US-Japan alliance credibility. The more China interprets Japan's autonomous strengthening of defense capabilities as a signal of the weakening of the US-Japan alliance [16], the more the center of gravity could shift toward an approach aimed at driving a wedge between the U.S. and Japan rather than pressuring Japan directly. Conversely, if Japan's independent military buildup itself is reassessed as a greater threat, the stance of direct pressure on Japan is likely to persist over the long term.