The Korean Peninsula and Japan after Eight Decades of Division:

Negative Chain Reactions among North Korea, South Korea, and Japan

Yoon Seok-jung

National Diplomatic Academy

I. The Divided Korean Peninsula and Japan in the Cold War Era

The year 2025 marks the 80th anniversary of Korea’s liberation from Japanese colonial rule. On August 15, 1945, the Korean Peninsula emerged from 35 years of colonial subjugation—but its liberation was immediately overshadowed by division.

Rather than full independence, the peninsula was partitioned along the 38th parallel, with the United States and the Soviet Union administering the South and North respectively.

The onset of the Cold War ensured that division hardened into permanence. In 1948, two separate governments were established, and with the outbreak of the Korean War in 1950, division escalated into systemic confrontation. The 1953 Armistice halted hostilities but cemented the Peninsula as a frontline of Cold War rivalry, with Seoul and Pyongyang entrenched under the respective patronage of Washington and Moscow.

Japan’s role in this history is complex. In 1965, twenty years after Korea’s division, South Korea and Japan normalized relations. However, negotiations failed to resolve fundamental issues surrounding the illegality of colonial rule and the matter of compensation.

Article 2 of the Basic Treaty—stating that “previous treaties are already null and void”—was interpreted differently: Seoul maintained that all pre-1910 treaties were invalid from the outset, while Tokyo argued that their nullification resulted from Korea’s independence.

The accompanying Claims Settlement Agreement was framed not as compensation but as the settlement of financial and civil claims, largely presented as economic cooperation. Cold War imperatives weighed heavily: Seoul required Tokyo’s support in its contest with Pyongyang over legitimacy and systems, and anti-communism became the driving force behind normalization.

This anti-communist alignment with Seoul had direct implications for Tokyo’s approach to Pyongyang. While Japan formally maintained that its relations with North Korea remained “a blank slate,” its choice to normalize ties with South Korea constrained its diplomatic maneuverability toward the North.

Japan could not risk undermining the security and economic benefits of its partnership with Seoul, an essential anti-communist outpost. Consequently, normalization with South Korea came at the expense of relations with North Korea, effectively foreclosing options for engagement.

Thus, Cold War–era relations among the Peninsula and Japan were shaped by a “negative chain reaction”: Seoul and Pyongyang engaged in mutual non-recognition and ideological hostility; Tokyo aligned with Seoul on the basis of anti-communist solidarity; and as a result, Tokyo’s relations with Pyongyang were locked into hostility and non-normalization.

The legacy of this chain remains visible in 2025—the 80th anniversary of Korea’s division, the 60th anniversary of Japan–South Korea normalization, and simultaneously, the 60th anniversary of Japan–North Korea non-normalization.

II. Contemporary Dynamics in 2025

The structure forged in the mid-20th century continues to shape present-day relations among the Peninsula and Japan. In this sense, Cold War legacies represent “history in the making.” As the German legal scholar Carl Schmitt noted in his concept of war as a state, a conflict may persist even after open hostilities end, if adversaries continue to perceive each other as enemies.

The Korean Peninsula remains in precisely such a condition. Hostilities ceased with the armistice, but the war has never formally ended, and both Koreas continue to treat each other as enemies. Japan, in turn, remains entangled in this unresolved conflict structure.

Two cases illustrate this persistence:

First, South Korea–Japan tensions amid Seoul’s peace initiatives. During the Moon Jae-in administration, Seoul pursued rapprochement with Pyongyang under the banner of a Korean Peninsula peace process. Yet as inter-Korean tensions temporarily eased, Seoul and Tokyo clashed over unresolved historical disputes.

This dynamic reflected a structural reality: the basis of Seoul–Tokyo cooperation has long rested on shared perceptions of a North Korean threat. When that threat perception diverged, bilateral frictions resurfaced—echoing Cold War–era zero-sum dynamics.

Second, the abduction issue and North Korea–Japan hostility. In 2002, Kim Jong-il admitted to the abduction of Japanese nationals, returning five survivors while claiming that eight had died. Japan, however, maintains that at least 17 citizens were abducted, with potentially more victims unacknowledged.

Tokyo views these abductions as tied to Pyongyang’s covert operations against both South Korea and Japan. The abduction issue has since become the central obstacle to normalization, reinforcing hostility. This too reflects the enduring linkage: inter-Korean confrontation perpetuates abnormal Japan–North Korea relations.

III. North Korea’s Hostile Two-State Doctrine and Implications for Japan

Since 2023, Pyongyang has recast the international order as a “new Cold War” and redefined inter-Korean relations as those of two hostile states. In January 2024, Kim Jong-un declared: “We must completely eliminate the concepts of unification, reconciliation, and kinship from the history of our republic.” Unlike the externally imposed division of 1945, this “two-state doctrine” represents a self-chosen perpetuation of division.

For Seoul, however, peaceful unification remains a valid and necessary policy objective. The more Pyongyang emphasizes hostility, the more Seoul must internationalize the discourse on peaceful unification and assert leadership in shaping the Peninsula’s future. Division, in Seoul’s view, is not permanent but a problem to be resolved through diplomacy and eventual reunification.

Japan too faces a choice. Since 1965, Tokyo has largely mirrored Seoul’s antagonism toward Pyongyang, paying its own price through unresolved issues such as abductions and non-normalization. Going forward, Japan must broaden its strategic perspective.

Rather than being constrained solely by the perception of North Korea as a shared threat, Tokyo should seek opportunities to cooperate with Seoul in fostering conditions for dialogue with Pyongyang. If inter-Korean relations improve, Japan could normalize ties with North Korea on a foundation not premised on hostility—advancing its broader interests in East Asia, including security, trade, and cultural exchange.

Conclusion

Eighty years after liberation and division, the Korean Peninsula and Japan remain bound by Cold War legacies. The negative chain reaction among North–South, South Korea–Japan, and North Korea–Japan relations continues to shape the region.

Breaking this cycle will require strategic flexibility, sustained dialogue, and future-oriented approaches in both Seoul and Tokyo. Only then can the abnormality of this trilateral relationship be overcome and replaced with a structure conducive to stability, cooperation, and peace in Northeast Asia.