In the mid-20th century, two countries—France and Germany—that had fought horrendous wars with one another for the past 70 years initiated an extraordinary experiment. Without signing a formal defense treaty, they started to weave their political, industrial, and military futures together on a step-by-step basis. As a result, the two countries established a strategic entente based on trust, habit, and consultation. Such a system transformed the erstwhile enemies into the key pillars of the European security structure.
Today’s Japan and South Korea are also standing at a similarly important crossroads. The two democracies are facing an increasingly unpredictable North Korea, an ascending and assertive China, and the growing probability of a simultaneous crisis—namely, the dual contingency—both in the Taiwan Strait and on the Korean Peninsula. At the same time, the crumbling credibility of the U.S.’s extended nuclear deterrence is further tested by Washington’s domestic political polarization and America’s global overextension.
In such an unstable environment, Tokyo and Seoul need to find ways to mutually strengthen their security even without a formal alliance. France and Germany’s experience after WWII demonstrates that through consistent and institutionalized cooperation, the two countries can achieve a deep relationship without a legally binding treaty.
Why a Formal Alliance Is Unrealistic
Discussions on a Japan–South Korea defense treaty reemerge whenever North Korea launches missiles or China flexes its muscles in the region. Nevertheless, such suggestions overlook the perennial structural and political constraints.
In the case of South Korea, the legacy of Japan’s colonization is still deeply imprinted in its people’s memory. Any measures that could be perceived as military normalization or as forming a formal alliance contain the risk of triggering domestic backlash. Meanwhile, for Japan, constitutional pacifism, public cautiousness about military intervention, and the priority on the Taiwan contingency function are key barriers on the path toward a Japan–ROK mutual defense treaty. Even if such legal and psychological hurdles are surmounted, the two governments face asymmetric security priorities—while Seoul focuses on the immediate North Korean threat, Tokyo tends to prioritize the regional balance vis-à-vis China.
Rather than forcing a formal treaty, both countries could pursue a “strategic entente,” a cooperative framework based upon shared capabilities and institutional mechanisms. Such an approach reflects the path that has been taken by France and Germany: a partnership through practice, not paperwork.
The Franco-German Blueprint
When Charles de Gaulle and Konrad Adenauer signed the Élysée Treaty in 1963, they did not include a mutual defense clause. Instead, what they structured was a near-permanent habit of consultation—regular summits, ministerial committees, youth exchanges, and military liaison channels. Such arrangements made consultations more predictable and ultimately transformed the bilateral relationship.
Throughout the decades after the treaty was signed, such political arrangements deepened into operational integration. The creation of the Franco-German Brigade (FGB) in 1989 symbolized reconciliation that went far beyond interoperability. Although France preferred its own independent nuclear deterrence capability and Germany remained in NATO, both countries’ defense industries and military doctrines became increasingly intertwined. As a result, the relationship survived despite political leadership changes, occasional crises, and divergent national interests.
Three lessons seem notable for Japan and South Korea. First, reconciliation and cooperation are simultaneous, not sequential. Simply working together more effectively creates trust instead of merely waiting for trust to materialize. Second, institutions sustain continuity when domestic politics oscillate. Third, symbolic actions of defense cooperation—albeit meager—could change public perception with the passage of time, eventually transforming erstwhile adversaries into necessary partners.
Applying the Franco-German Lessons to East Asia
Just as France and Germany understood that survival depended on mutual cooperation, Japan and South Korea are now facing more converging strategic imperatives. As U.S. allies, both countries are exposed to the unpredictability of Washington’s strategic bandwidth; they are also positioned at the very forefront of a potential great-power clash; and the two countries possess advanced defense-industrial capabilities that could maximize their effectiveness through cooperation rather than duplication.
The first measure to be taken is institutionalization. Tokyo and Seoul could establish a Japan–Korea Security Council, modeled upon the Franco–German Council of Ministers. The Council could hold two rounds of meetings annually, co-chaired by defense and foreign ministers. It could also establish a permanent secretariat, which would manage intelligence, defense R&D, supply chain security, and communication under crisis.
Second, joint capability development should be expanded. Cooperative projects in the fields of unmanned systems, C-UAS, and electronic warfare could enhance interoperability and economies of scale. Franco-German joint industrial ventures—exemplified by Airbus and MBDA—offer precedents for integrating strategic industries without impairing sovereignty.
Third, operational cooperation should be routinized. Japan and South Korea are already sharing intelligence through the General Security of Military Information Agreement (GSOMIA). Such a mechanism could further develop into real-time data fusion linking missile defense networks and C4ISR. Meanwhile, joint maritime and air exercises, humanitarian operations, and the exchange of liaison officers would gradually naturalize defense cooperation. The creation of a symbolic Japan–Korea Peace Brigade for disaster relief and UN operations could replicate the unifying role of the Franco–German Brigade.
Lastly, societal trust-building should not be overlooked. Just as the Franco-German youth exchanges and academic partnerships created a generation that perceived cooperation as a norm, Tokyo and Seoul could expand joint programs for defense-related scholars, junior officers, and technologists. Long-term reconciliation is based on shared professional and cultural experience.
Adapting to East Asia’s Realities
To be sure, history never repeats in an identical manner. The Franco-German reconciliation was conducted under the aegis of NATO and U.S. guidance. On the other hand, Japan and South Korea must take steps under a direct nuclear threat while great-power rivalry has escalated in the region. Yet such unfavorable conditions further necessitate cooperation between the two countries.
Unlike postwar Europe, a collective security system does not exist in East Asia. Such an absence indicates that Tokyo and Seoul need to structure their own institutional basis. Cooperation between both countries should be modular and flexible, allowing each partner to selectively choose areas of cooperation—missile defense, cyber, space, logistics, etc.—without imposing rigid mutual defense obligations.
Just as France and Germany accepted different roles—France as a nuclear power and Germany as a key pillar of conventional arms—Japan and South Korea could accept asymmetry. For instance, Japan could take a leading role in missile defense and maritime surveillance, while South Korea could center its focus on counter-battery systems and tactical air capabilities. What matters is not identical capability but rather achieving interoperability under a common strategic objective.
Beyond Alliance: Toward an East Asian Strategic Community
If the aforementioned measures are fully implemented, they could evolve into an inclusive core of an East Asian Security Community that is based on trust, interoperability, and shared democratic values. Such development would reduce Washington’s need to mediate every regional crisis, eventually strengthening the U.S. alliance network rather than weakening it.
The Franco–German case reminds us that the path from enmity to rapprochement is never short nor linear. It requires leaders who can think beyond election cycles and publics who can imagine a future vision rather than past scars. Yet history shows that when two countries have the courage and willingness for cooperation, it can not only change their relationship but also the regional structure itself.
In 1963, the Élysée Treaty—a once unthinkable miracle—was signed between France and Germany. After six decades, a similar miracle is needed in East Asia. For Japan and South Korea to become strategic partners, a formal treaty is not necessary; what is needed is vision, discipline, and political will that could institutionalize cooperation. If Tokyo and Seoul pursue the Franco-German example with perseverance and creativity, both countries could lead the Indo-Pacific into a zone of peace and stability for the next half-century.
