Japan’s latest general election has delivered a political shockwave. Early tallies flashing across screens in Tokyo showed a historic outcome: the Liberal Democratic Party (LDP), under Prime Minister Sanae Takaichi, secured 316 of the 465 seats in the House of Representatives. Together with coalition partners, Takaichi now commands a two-thirds supermajority, an unprecedented mandate and the most decisive victory in the LDP’s seven-decade history. Effectively, it marks the end of Japan’s long era of political caution.
This landslide was driven by a potent mix of public yearning for strong leadership and a highly effective digital campaign. Takaichi, widely seen as the most faithful ideological heir to the late Shinzo Abe, successfully tapped into nationalist sentiment among younger voters through her “Japan First” narrative. Electoral data show that voters under 30 formed the backbone of the LDP’s surge, dwarfing opposition support that appeared increasingly incoherent and directionless. Equally decisive was the opposition’s failure to articulate a compelling alternative vision.
With two-thirds of parliament under her control, Takaichi now holds what amounts to a blank cheque to reshape Japan’s national trajectory. Legislative obstacles to major strategic shifts have largely evaporated. The world is now poised to witness the emergence of the most assertive Japan since the end of World War II.
Washington, unsurprisingly, stands to benefit from this convergence, as the strategic narratives of both governments now align almost seamlessly. Yet this new reality will also force every Southeast Asian capital, Jakarta foremost among them, to urgently recalibrate its diplomatic posture toward a far more muscular Japan — and could result in proliferation of military technologies across the ASEAN nations.
Revising Article 9
Domestically, the supermajority opens the door to what has long been Japan’s most sensitive political taboo: amending Article 9 of the constitution. Takaichi has previously stated, “Constitutional revision is the LDP party line. I hope that concrete amendment proposals can be fully discussed in the Diet Commission on the Constitution.”
The pacifist clause, which legally constrains Japan’s ability to maintain warfighting forces, is now under existential threat. Armed with a two-thirds majority, Takaichi has the procedural power to initiate a national referendum to remove these military restrictions. Her ambition to turn Japan into a “normal” state, economically powerful yet also militarily capable of defending its sovereignty, has never been more attainable.
Military normalisation would allow Tokyo to openly develop long-range missile systems and aircraft carrier fleets without hiding behind euphemisms. Japan would no longer be a passive observer but an active player, ready to intervene should its vital sea lanes come under threat. Japan’s defence posture would shift permanently from shield to sword, with explicit counter-strike capabilities.
At home, Takaichi is expected to overhaul Japan’s defence industry to make it globally competitive. Freed from constitutional constraints, firms such as Mitsubishi Heavy Industries would gain a green light to export advanced military technologies, creating new dependencies among partner states. Takaichi appears acutely aware that military autonomy is a prerequisite for political autonomy, particularly in managing a sometimes unpredictable alliance with the United States.
In Japan’s backyard, a more militaized Japan likely puts at risk decades of painstaking historical reconciliation with China and South Korea, with wartime grievances resurfacing, fuelling diplomatic confrontations with potentially destabilising effects on regional investment and economic confidence.
For Beijing, this is a strategic alarm bell: the end of a pacifist Japan that long served China’s interests. Takaichi will likely to deepen Japan’s role in the Quad and seek entry into AUKUS’ second pillar. Such moves would create a new security pole challenging China’s dominance along the First Island Chain.
But the reverbations will be felt throughout the Pacific, including in the southern waters.
ASEAN’s Strategic Backyard
One of the clearest policy shifts under a Takaichi supermajority will be the expansion of Japan’s Official Security Assistance (OSA). For decades, Tokyo supported ASEAN primarily through economic aid. OSA marks a decisive break, providing direct assistance to strengthen the military capabilities of neighbouring states. With an overwhelming parliamentary mandate, Takaichi is likely to dramatically increase OSA funding as part of a systematic effort to build a strategic buffer around China’s sphere of influence in the South China Sea, with ASEAN as its anchor.
For Indonesia, the implications would be substantial. Japan has already begun supporting maritime radar upgrades in sensitive areas such as the Natuna waters. With virtually unlimited fiscal space, Tokyo is expected to offer highly attractive defence packages, ranging from undersea surveillance systems to advanced reconnaissance drones.
OSA will become Takaichi’s primary instrument of defence diplomacy, aimed at ensuring ASEAN can resist pressure from Beijing without relying exclusively on an often conditional and politically fraught American security umbrella. Yet behind OSA lies a broader geostrategic design. Japan seeks to constrain China’s military access through a network of ASEAN states equipped with Japanese defence technology, what strategists would describe as “proximal deterrence.”
For ASEAN, this will be a difficult and risky offer to refuse. Accepting Japanese military assistance will almost certainly be read in Beijing as a political alignment. This is especially sensitive as OSA is also projected to extend into cybersecurity, including Japan’s proposal to develop undersea cable infrastructure to reduce ASEAN’s dependence on Chinese telecommunications technology.
The real objective of OSA is not merely assistance, but integration, binding ASEAN into Japan’s security and technological ecosystem. Backed by a supermajority, Takaichi has the budgetary flexibility to heavily subsidise these initiatives. For Tokyo, safeguarding ASEAN’s security is the most effective way to protect the maritime arteries that sustain Japan’s economy. Still, the policy’s success will hinge on Tokyo’s ability to navigate ASEAN’s sovereignty sensitivities, lest OSA be perceived as a form of “new imperialism.”
ASEAN’s Dilemma
Sanae Takaichi’s overwhelming victory presents ASEAN with a double-edged sword. On the positive side, a more assertive Japan offers an alternative strategic balancer beyond the United States. Countries such as the Philippines and Vietnam are likely to view Takaichi as a new security guarantor against aggressive territorial claims in the South China Sea. Under her leadership, Japan could emerge as a more predictable security provider than the United States, whose foreign policy often fluctuates with domestic electoral cycles.
The risks, however, are equally profound. Takaichi’s stark, black-and-white approach toward China threatens ASEAN centrality and Indonesia’s long-standing “free and active” foreign policy. Her aggressive promotion of a Free and Open Indo-Pacific will pressure ASEAN to redefine its strategic position.
If Japan pushes too hard for ASEAN to choose sides in a confrontation with China, internal fractures could deepen and become increasingly irreparable. Cambodia and Laos, economically dependent on Beijing, would drift further to the margins, while maritime states such as Indonesia would be forced into exhausting diplomatic balancing acts. The most dangerous scenario is a bifurcated ASEAN, a China-leaning mainland bloc and a maritime bloc aligned with Japan and the United States.
Should this occur, ASEAN’s relevance as a neutral regional institution would erode, turning Southeast Asia into a fragile buffer zone for competing external ambitions.
Looking ahead, Southeast Asian politics may be entering a phase best described as an “equilibrium of tension.” As Takaichi realises her ambitions, ASEAN is likely to become more militarised. Defence cooperation with Japan will extend beyond joint exercises to include logistical facilities at key maritime chokepoints. Indonesia, in particular, will need to leverage OSA to strengthen national sovereignty without becoming a pawn in an anti-China alliance.
The Takaichi era is a stark warning that the peace ASEAN has long enjoyed may soon demand a far higher political price.
Ronny P. Sasmita is the Senior International Affairs Analyst at the Indonesia Strategic and Economics Action Institution