With Japan’s Liberal Democratic Party securing a two‑thirds legislative supermajority, how could this political dominance accelerate constitutional amendment debates, particularly regarding collective self‑defence, and what are the broader implications for regional power dynamics in East Asia?
Japan's political landscape underwent a seismic transformation on February 8, 2026, when Prime Minister Sanae Takaichi's Liberal Democratic Party secured a historic landslide victory, winning at least 310 seats in the 465-member House of Representatives—the first time since World War II that a single party has won more than two-thirds of Lower House seatsLDP secures supermajority in Lower House election victory | The Asahi Shimbunasahi . This unprecedented political consolidation positions the ruling coalition to accelerate long-stalled constitutional amendment debates, though significant procedural hurdles and regional tensions complicate the path forward.
The LDP's electoral triumph surpassed all previous party records, exceeding the 300-seat benchmark set under Prime Minister Yasuhiro Nakasone in 1986Japanese prime minister's party secures sweeping majority ...rmoutlook . Together with coalition partner Japan Innovation Party (Ishin), the ruling bloc secured as many as 366 of the 465 Lower House seatsPM Sanae Takaichi’s party set for majority in Japan parliamentary elections | News | Al Jazeeraaljazeera , establishing commanding control over the chamber's legislative agenda.
The opposition suffered catastrophic losses. The newly formed Centrist Reform Alliance, comprising the Constitutional Democratic Party of Japan and Komeito (which ended its long-standing alliance with the LDP in October 2025), saw its pre-election share of 167 seats reduced by more than two-thirdsJapan's ruling party on track for an overwhelming majority ...lemonde . This collapse effectively eliminated meaningful parliamentary opposition to the ruling coalition's constitutional agenda.
The Lower House supermajority carries immediate practical consequences. With 310 or more seats, the LDP-led coalition can override any bills rejected by the Upper House LDP set for big win in snap election - The Japan Times japantimes , neutralizing the chamber where the coalition lacks majority control.
Japan's Constitution, drafted under U.S.-led occupation forces after World War II, has never been amended. Article 96 establishes a rigorous two-stage process: amendments must first secure "a concurring vote of two-thirds or more of all the members of each House" before proceeding to a national referendum requiring "the affirmative vote of a majority of all votes cast"THE CONSTITUTION OF JAPANkantei .
The ruling coalition's constitutional ambitions face a critical bottleneck in the House of Councillors. Following the July 20, 2025 election, the LDP-Komeito coalition fell short of the 50 seats required to maintain Upper House majorityIshiba's LDP Coalition Loses Majority in Japan's Upper House Election: Smaller Parties Make Gains in Fragmented Landscape | Nippon.comnippon . The LDP secured 39 seats while Komeito won 8 seats in that electionIshiba's LDP Coalition Loses Majority in Japan's Upper House Election: Smaller Parties Make Gains in Fragmented Landscape | Nippon.comnippon . With Komeito's subsequent defection to the opposition and formation of the Centrist Reform Alliance, the LDP-Ishin coalition now faces an even more challenging Upper House arithmetic.
Prior to the political realignment, the LDP held 113 Upper House seats while Ishin held 18 seatsHouse of Councillors - Wikipediawikipedia . The constitutional amendment threshold in the 248-member Upper House requires 166 seats—a margin the current ruling coalition cannot achieve without additional support.
A senior Takaichi administration official acknowledged these constraints: "We won't be able to formally propose it until at least the next Upper House election, but if we secure two-thirds in the Lower House, we will advance the discussion"Constitutional revision backers hope to gain supermajority | The Asahi Shimbun: Breaking News, Japan News and Analysisasahi . The next House of Councillors election is expected by July 31, 2028Japan House of Councillors July 2025 Election | Election results | Japan | IPU Parline: global data on national parliamentsipu .
Nevertheless, momentum is building rapidly. In the 2025 coalition agreement between the LDP and Ishin, the parties agreed to establish a committee for Article 9 revisionJapan's 2026 Election: National Security | Council on Foreign Relationscfr . This constitutional revision committee began deliberations in November 2025 and aims to submit a draft to the Diet by the end of March 2026Japan's 2026 Election: National Security | Council on Foreign Relationscfr .
Article 9 of Japan's Constitution renounces war and states that "land, sea, and air forces, as well as other war potential, will never be maintained"Coalition pushes revival of ranks from imperial military daysasahi . This pacifist framework has shaped Japanese defense policy since 1947, creating legal ambiguity around the Self-Defense Forces' constitutional status.
The LDP seeks a relatively conservative approach—adding language to formally acknowledge the Self-Defense Forces' existence while maintaining the article's existing frameworkJapan pushes constitutional change to recognize military forcesdefence-blog . Prime Minister Takaichi articulated this position clearly: "Why can't we write the Self-Defense Forces into the Constitution? I want you to let us revise the Constitution to position them as an effective organization"Constitutional revision backers hope to gain supermajority | The Asahi Shimbun: Breaking News, Japan News and Analysisasahi .
Party officials argue that the absence of clear constitutional status creates legal and political ambiguity for Japan's military personnelJapan pushes constitutional change to recognize military forcesdefence-blog . This approach builds on the late Prime Minister Shinzo Abe's proposals to add language formally acknowledging the SDF while preserving the pacifist frameworkJapan pushes constitutional change to recognize military forcesdefence-blog .
Coalition partner Ishin advocates a more hawkish approach that represents "a significant departure from the LDP's more cautious stance" LDP and JIP see different paths for constitutional revision - The Japan Times japantimes . Specifically, Ishin proposes:
Both parties agree on maintaining current wording about renouncing war as a sovereign right and want to add wording making clear the legal existence of the Self-Defense ForcesIn Japan, pro-revision parties differ on what to change in the constitution | ConstitutionNetconstitutionnet . However, the substantive differences regarding paragraph two deletion and collective self-defense expansion remain unresolved.
Alongside Article 9 revision, the ruling coalition is pursuing an "emergency powers clause" that would concentrate legislative authority in the cabinet during major disasters or armed attacksJapan Election Landslide Opens Door to Constitutional Reform - Seoul Economic Dailysedaily . Last November, the LDP and Ishin compiled drafts for both Article 9 and an emergency situations clause, intending to formally present them for Diet debateConstitutional revision backers hope to gain supermajority | The Asahi Shimbun: Breaking News, Japan News and Analysisasahi .
Analysis from the Sasakawa Peace Foundation notes that while these drafts focus on consolidating authority for emergency measures, "they cannot be regarded as having been formulated with a strong awareness of human rights protection"The Current Status of Emergency Legislation in Japan and ...spf . The proposed Basic Emergency Act would grant the government temporary authority to respond quickly, with mechanisms to ensure existing legal frameworks are immediately applied once emergencies are liftedThe Current Status of Emergency Legislation in Japan and ...spf .
Japan's collective self-defense posture has evolved significantly since 2014, when the Abe Cabinet reinterpreted the Constitution as permitting collective self-defense. The 2015 Armed Attack Situation Act established the concept of a "crisis of national survival" (survival-threatening situation) as permitting collective self-defense actionTakaichi's Taiwan Remarks: Much Ado About Nothing? - The Diplomatthediplomat .
On November 7, 2025, Prime Minister Takaichi made statements that dramatically escalated regional tensions. Responding to opposition questioning about a hypothetical Chinese blockade of the Taiwan Strait, she stated: "If battleships are used and a naval blockade involves the use of force, I believe that would, by any measure, constitute a 'survival-threatening situation' for Japan"Text - H.Con.Res.71 - 119th Congress (2025-2026): Expressing ...congress .
The legal term "survival-threatening situation" under Japanese law allows Tokyo to exercise its right to collective self-defense with the United StatesText - H.Con.Res.71 - 119th Congress (2025-2026): Expressing ...congress . Takaichi further clarified that "the Japanese government would make its judgment by synthesizing all information based on the specific circumstances of the actual situation"Text - H.Con.Res.71 - 119th Congress (2025-2026): Expressing ...congress .
This marked "the first time since the end of World War II" that a Japanese leader "explicitly linked a 'Taiwan contingency' to a potential 'survival-threatening situation' for Japan in a formal setting"Embassy spokesperson’s article on Executive Intelligence Review: Jointly Safeguard the Hard-Won Victory of World War II and Stop the Resurgence of Militarism_Embassy of the People's Republic of China in the United States of Americachina-embassy .
A Kyodo News survey showed that 48.8 percent of respondents supported the exercise of collective self-defense in a Taiwan contingencyEscalating Japan-China Tensions: Insights from the Past and Prospects for the Futurecsis . Following Takaichi's statement, multiple polls showed majority approval: Nikkei showed 55 percent found her statement appropriate, Yomiuri Shimbun showed 56 percent approved, and Asahi Shimbun showed 56 percent found her statement appropriateJapan's 2026 Election: National Security | Council on Foreign Relationscfr .
Beijing's response to Japan's constitutional trajectory and Taiwan-related statements has been exceptionally sharp. Following Takaichi's November 2025 remarks, China's Foreign Ministry spokesman Lin Jian warned: "If Japan should dare to intervene militarily in the Taiwan Strait situation, it would constitute an act of aggression and would face a firm and resolute response from China"China ups war of words as Japan starts talks on amending post-war constitution - Washington Timeswashingtontimes . He added ominously: "Those who play with fire will perish by it!"China ups war of words as Japan starts talks on amending post-war constitution - Washington Timeswashingtontimes
Chinese officials explicitly invoked Japan's wartime history, with Lin stating: "Over the last century, Japanese militarists have waged aggression more than once under the pretext of a 'survival-threatening situation'"China ups war of words as Japan starts talks on amending post-war constitution - Washington Timeswashingtontimes . China's Consul General in Osaka, Xue Jian, posted on social media that Takaichi should be "beheaded"—a remark later deleted but never officially retractedTakaichi's Taiwan Remarks: Much Ado About Nothing? - The Diplomatthediplomat .
In a January 2026 statement, China's Foreign Ministry characterized Japan's security developments as reflecting "the dangerous trend of Japan 'remilitarizing' itself faster, which is bound to undermine regional peace and stability"Foreign Ministry Spokesperson Mao Ning’s Regular Press Conference on January 6, 2026_Ministry of Foreign Affairs of the People's Republic of Chinamfa . The ministry invoked international legal instruments including the Cairo Declaration and Potsdam Proclamation, which require Japan to be "completely disarmed"Foreign Ministry Spokesperson Mao Ning’s Regular Press Conference on January 6, 2026_Ministry of Foreign Affairs of the People's Republic of Chinamfa .
Beijing's Foreign Ministry also challenged Japan's characterization of cross-strait issues, emphasizing that "Taiwan's return to China is an integral part of the post-war international order" and that "how to resolve the Taiwan question is a matter for the Chinese ourselves and Japan is in no position to make any interference"Foreign Ministry Spokesperson Guo Jiakun’s Regular Press Conference on December 16, 2025_Ministry of Foreign Affairs of the People's Republic of Chinafmprc .
Taiwan's response has been measured but supportive of Japan's stance. The ROC Foreign Ministry issued a statement on November 11, 2025, asserting that "the ROC (Taiwan) is a sovereign, independent nation; that its sovereignty belongs to the Taiwanese people; that neither the ROC (Taiwan) nor the People's Republic of China is subordinate to the other; and that the PRC has never governed Taiwan"The PRC’s Diplomatic Offensive Against Japan Over Taiwan | Global Taiwan Instituteglobaltaiwan .
Taiwan's Ministry of Foreign Affairs welcomed joint statements by Japanese and Australian defense ministers in December 2025 reaffirming that "peace and stability across the Taiwan Strait were essential to regional and international security and prosperity"MOFA response to Japan and Australia defense ministers' joint ...mofa . Foreign Minister Lin Chia-lung expressed appreciation for these remarks and called on China to "cease all reckless actions that heighten tensions"MOFA response to Japan and Australia defense ministers' joint ...mofa .
ROC Premier Cho Jung-tai asserted in November 2025 that "reunification" with China was "not an option" for Taiwan, declaring that "the Republic of China, Taiwan, is a fully sovereign and independent country"The PRC’s Diplomatic Offensive Against Japan Over Taiwan | Global Taiwan Instituteglobaltaiwan .
South Korea's position reflects both alliance cooperation and historical sensitivities. Japan has "positively responded to South Korea's repeated calls for Seoul's consent before exercising its collective self-defense right on and around South Korea's land, sea, and air territory"Japan to ask for S.Korea's consent over self-defense right / YTNyoutube . Under the revised law drafted by Japan's ruling coalition, "Tokyo will be able to exercise its collective self-defense right overseas only when it gets consent from the related nations"—meaning Japan should obtain consent from South Korea for any collective self-defense action on and around the Korean PeninsulaJapan to ask for S.Korea's consent over self-defense right / YTNyoutube .
South Korea's foreign ministry has maintained that "Japanese forces will not be allowed on the Korean peninsula without prior consent" and has urged Tokyo to "adhere to the basic spirit of the pacifist constitution and carry out any follow-up measures in a transparent manner"DAY BREAK 06:00 Japan adopts resolution allowing collective self-defenseyoutube .
Bilateral tensions have complicated coordination, with South Korean jets conducting drills over Dokdo/Takeshima—disputed territory controlled by Korea but claimed by Japan. Chinese commentators attempted to exploit these tensions by "urging South Koreans to take China's side in historical and territorial disputes"China ups war of words as Japan starts talks on amending post-war constitution - Washington Timeswashingtontimes .
North Korea has condemned Japan's constitutional revision efforts in stark terms. The Korean Central News Agency characterized Japan's push as revealing its "militaristic nature to change the constitution, the fundamentals of the state, and emerge as the worst war force threatening the region to opt for a straight course for reinvasion"North Korea slams Japanese ruling party’s constitutional amendment push - The Korea Heraldkoreaherald .
DPRK commentary specifically targeted trilateral security cooperation, calling Japan's collaboration with South Korea and the U.S. "a military scheme to carry out a reinvasion of the Korean Peninsula"North Korea slams Japanese ruling party’s constitutional amendment push - The Korea Heraldkoreaherald . A December 2025 statement warned that "Japan's attempt to go nuclear must be prevented" and characterized recent developments as showing Japan's "bellicose and aggressive nature"Japan's attempt to go nuclear must be prevented: DPRKnews .
Washington has signaled support for Japan's expanded collective self-defense capabilities. Former Assistant Secretary of State for East Asia Kurt Campbell endorsed Tokyo's push, stating that "individual self-defense and police authority are not enough to handle new forms of threat in the region"Former U.S. official endorses Japan's right to collective self-defenseyoutube .
The State Department reaffirmed alliance commitments following the November 2025 controversy, with Deputy Spokesperson stating: "Our commitment to the U.S.-Japan Alliance and to Japan's defense, including the Japan-administered Senkakus, is unwavering. The U.S.-Japan Alliance remains the cornerstone of peace and security in the Indo-Pacific"Text - H.Con.Res.71 - 119th Congress (2025-2026): Expressing ...congress .
Southeast Asian nations have generally welcomed enhanced Japan-ASEAN defense cooperation. At the 15th Anniversary ADMM-Plus meeting, participants acknowledged that "Japan-ASEAN defense cooperation will contribute even more to peace and prosperity in the Indo-Pacific" Minister of Defense Koizumi’s Participation in the 12th ASEAN Defence Ministers’ Meeting Plus (Summary)mod .
ASEAN member states "praised Japan's cooperation in various fields" and "expressed particular appreciation for Japan's support of the ASEAN Outlook on the Indo-Pacific"The 28th ASEAN Japan Summit | Ministry of Foreign Affairs of Japanmofa . Multiple countries welcomed the Japan-ASEAN AI Co-creation Initiative proposed by Prime Minister TakaichiThe 28th ASEAN Japan Summit | Ministry of Foreign Affairs of Japanmofa .
Public attitudes toward constitutional amendment present a nuanced picture. A 2025 Yomiuri Shimbun poll found 60 percent of voters favor amending the Constitution—the fourth consecutive year this figure has remained in the 60 percent rangeYomiuri Poll: 60％ in Favor of Amending Japan Constitution; Figure in 60％ Range for Fourth Consecutive Year - The Japan Newsyomiuri . Significantly, 74 percent said political parties should engage in more active constitutional discussionsYomiuri Poll: 60％ in Favor of Amending Japan Constitution; Figure in 60％ Range for Fourth Consecutive Year - The Japan Newsyomiuri .
However, opinions diverge sharply on specific provisions:
These findings suggest that while the public generally supports constitutional debate, there remains significant resistance to substantive changes to the pacifist provisions—potentially complicating any future referendum.
Japan has increased its defense budget for 13 consecutive years, with fiscal year 2026 defense spending reaching over 9 trillion yen (approximately $58 billion USD)—a new recordEmbassy spokesperson’s article on Executive Intelligence Review: Jointly Safeguard the Hard-Won Victory of World War II and Stop the Resurgence of Militarism_Embassy of the People's Republic of China in the United States of Americachina-embassy . This represents achievement of the 2% of GDP target ahead of scheduleEmbassy spokesperson’s article on Executive Intelligence Review: Jointly Safeguard the Hard-Won Victory of World War II and Stop the Resurgence of Militarism_Embassy of the People's Republic of China in the United States of Americachina-embassy . Japanese defense firms saw combined arms sales surge approximately 40 percent year-over-year to $13.3 billion in 2024—the world's fastest growth according to SIPRIEmbassy spokesperson’s article on Executive Intelligence Review: Jointly Safeguard the Hard-Won Victory of World War II and Stop the Resurgence of Militarism_Embassy of the People's Republic of China in the United States of Americachina-embassy .
Prime Minister Takaichi has finalized a roadmap to submit a constitutional amendment bill explicitly recognizing the Self-Defense Forces by next monthJapan Election Landslide Opens Door to Constitutional Reform - Seoul Economic Dailysedaily . However, amendments require two-thirds approval in both chambers, and the ruling coalition currently falls short in the House of CouncillorsJapan Election Landslide Opens Door to Constitutional Reform - Seoul Economic Dailysedaily .
The realistic timeline points toward the 2028 Upper House election as the critical juncture. Should the LDP-Ishin coalition secure two-thirds control of both chambers, constitutional amendments could proceed to referendum for the first time in Japanese history. The coalition's Lower House supermajority ensures any Upper House opposition can be overridden on ordinary legislation, but constitutional amendments remain subject to the stricter two-thirds requirement in both chambers.
Japan's constitutional trajectory is reshaping East Asian security dynamics along several dimensions:
Taiwan Strait: Japan's explicit linkage of Taiwan contingencies to "survival-threatening situations" creates a framework for potential military involvement alongside the United States, fundamentally altering deterrence calculations.
Sino-Japanese Relations: Beijing's increasingly strident warnings and historical rhetoric suggest bilateral relations may deteriorate further as constitutional revision progresses.
U.S. Alliance System: Enhanced Japanese collective self-defense capabilities strengthen the hub-and-spokes alliance architecture, though Korean consent requirements on peninsula operations reflect ongoing trilateral coordination challenges.
Arms Buildup Dynamics: Mutual accusations of militarization between Japan and China risk creating a security spiral, with each side citing the other's buildup as justification for its own.
The LDP's unprecedented electoral mandate has created political conditions for accelerating constitutional debates that have been stalled for seven decades. While procedural hurdles in the Upper House delay formal amendment proposals, the coalition's legislative dominance enables immediate advancement of security legislation and defense spending without constitutional change. The coming years will determine whether Japan's political transformation translates into fundamental alteration of the pacifist constitutional order that has defined the nation's postwar identity.