The foundation of diplomacy lies in dialogue and negotiation for goodwill and cooperation. However, there are times when a firm warning message is necessary. Amid a security environment where the authoritarian alliance of North Korea, China, and Russia is strengthening, South Korea must consider applying a Korean version of the "Hallstein Doctrine" against states that exploit the division of the Korean Peninsula for their own interests.

Adopted by West Germany in 1955, the Hallstein Doctrine declared that diplomatic relations would be severed with any country that recognized East Germany as a sovereign state. It was a strategy to assert that West Germany was the sole legitimate government of Germany. Though controversial and imperfect, the doctrine at least delivered a strong rebuke to opportunistic diplomacy disguised as neutrality. By leveraging the clear power gap between East and West Germany, it forced other nations to make unambiguous choices.

South Korea once adopted a similar policy but withdrew it in 1973 through the "June 23 Peaceful Unification Foreign Policy Declaration," accepting simultaneous diplomatic relations with both Koreas. This choice, driven by the détente era and the economic reversal between the two Koreas, was rational for managing tensions on the peninsula.

However, the situation has changed. North Korea now defines the two Koreas as "hostile states" and refuses dialogue. Moreover, it claims to be a nuclear power, threatening the U.S. mainland with intercontinental ballistic missiles and holding South Korea hostage with tactical nuclear weapons. Kim Jong-un’s regime openly aspires to achieve "territorial integrity" through nuclear arms, fearing that the existence of a free and prosperous South Korea poses a political threat.

Yet, some countries that maintain simultaneous diplomatic ties with both Koreas enjoy economic benefits from South Korea while providing political legitimacy to the North Korean regime. Vietnam, Laos, and Indonesia—all recipients of South Korea’s Official Development Assistance (ODA) and trade partners worth hundreds of billions of dollars—sent delegations to North Korea’s 80th Labor Party anniversary in October 2025. These nations supply political and diplomatic oxygen to a regime marred by nuclear weapons, human rights abuses, and violations of international norms, engaging in classic "two-legged diplomacy." Notably, Indonesia, a partner in the KF-21 next-generation fighter jet development project, signed a technology cooperation agreement with North Korea, posing a clear security risk.

Given this, South Korea’s existing diplomatic policy premised on simultaneous diplomatic ties must be reconsidered. For years, Seoul has passively tolerated these countries’ choices as matters of sovereignty. However, if they politically align with or cooperate with the North Korean regime—which normalizes nuclear armament and antagonizes South Korea—it cannot be overlooked. While Russia and China, overt sponsors of North Korea, may be beyond Seoul’s influence, South Korea must send a resolute message to nations within its diplomatic reach. A Korean "Hallstein Doctrine" would be a concise expression of this message: maintaining cooperation while holding accountable states that exhibit dual-faced or opportunistic behavior in political and military matters. It should clarify that market, capital, technology, and security cooperation with South Korea is never a "free lunch."

If perceived as a diplomatic "spineless nice person," a nation becomes prey to international predation. Interest-driven pragmatic diplomacy functions only on a foundation of correct principles. If South Korea fails to exert influence proportional to its contributions, it is an act of self-deprecation and self-harm. It must firmly say "No" to states that exploit the division of the Korean Peninsula and undermine its core security interests. This is why a Korean "Hallstein Doctrine" is needed today.

* The view expressed herein was published on January 11 in The Chosun Ilbo and does not necessarily reflect the views of The Asan Institute for Policy Studies.