The security situation on the Korean Peninsula is changing drastically: as the inter-Korean relationship improved after the PyeongChang Olympics in the early 2018, the historical U.S.-DPRK summit was held in June, followed by the U.S.-ROK-DPRK trilateral summit at Panmunjom a year after. The U.S.-DPRK negotiation and the process toward a peace regime on the Korean peninsula are likely to progress simultaneously in parallel. This will also bring about changes in the roles of the U.S.-ROK alliance, the U.S.-Japan alliance, and the UN Command (UNC) in South Korea. In order to induce North Korea’s denuclearization, establish a peace regime in the peninsula, and comprehensively strengthen our national security, we should wisely modify the role of the alliance with the United States, which has been the main pillar of our national security. At the same time, it is desirable to pursue a multilateral security cooperation throughout Northeast Asia that combines functional and military-security cooperations. This is a policy that has a good cause for implementation since it fits the interests of neighboring countries as well as maximizes Korean national interests by seeking peace and co-prosperity in Northeast Asia. In particular, we should utilize the mutual reinforcement between the multilateral cooperation and the North Korea denuclearization, as the former stimulates the latter and the latter in turn recharges the impetus for the former.

In this context, this article will first, review the efforts and policies for the Northeast Asia multilateral security cooperation made by previous and current South Korean governments; second, recapitulate the necessity of such multilateral cooperation under the great transitions happening in the Korean peninsula; third, review the constraints to overcome and facilitators to utilize for the Moon Jae-in government to establish this; and fourth, propose strategies and policies to make it come true.

There are various ways to establish a multilateral security cooperation system in Northeast Asia, rather than only one right course to adhere to. The government should not insist upon certain means but should consider and carry out three options simultaneously: utilizing the six-party talks, utilizing the peace treaty, and further developing the Northeast Asia Peace and Cooperation Initiative. Until the inter-governmental cooperation is institutionalized, the government should support semi-governmental or non-governmental organizations that advocate multilateral security cooperation in Northeast Asia. At the same time, the government should take advantage of the existing multilateral cooperation regimes, such as ROK-China-Japan and ROK-U.S.-Japan trilateral cooperations, Eurasian communities for economy and culture, and micro-multilateralism among countries that share values and interests.

It is also encouraging that China and North Korea have recently been more forward-looking than in the past regarding multilateral security cooperation. If the denuclearization progresses and the end-of-war declaration is adopted, the inter-Korean relationship will be improved; the UN sanction will be alleviated, stimulating the inter-Korean economic cooperation; discussions for North Korea’s diplomatic normalizations with the U.S. and Japan will begin, and thus reduced hostility will facilitate the multilateral security cooperation in Northeast Asia. Because the role of the U.S. alliances with South Korea and Japan will be adjusted to prioritize the peacekeeping function over the deterrence, defensive, and offensive functions, the possibility that North Korea or China, so far negative or passive toward multilateral security, agree to join will become higher.

As we can see from the fact the United States has recently strengthened the function and role of the UNC, it is likely that they would want to maintain the UNC in South Korea even after the peace agreement. A thorough examination on our part is required, for dissolution of the UNC may impact negatively on South Korean security. In particular, nuclear security is imperative; therefore, the peace agreement, which may potentially lead to dissolution of the UNC, must be signed after, or at the same time as, the completion of North Korea’s nuclear disarmament. It is most important to ensure that denuclearization or peace agreement should not necessarily accompany evacuation of the U.S. Forces Korea (USFK) or breakup of the U.S.-ROK alliance.

Whether Northeast Asia multilateral security cooperation is realized or not, the existence, status, and function of the USFK and the U.S.-ROK alliance under the peace regime will depend on the role they would play in the unification process as well as the security situation and dynamics around the peninsula at the time. Considering the Soviet Union's policy toward West Germany in the course of German reunification, China might demand not only denuclearization but also neutralization of the Korean Peninsula or simultaneous operation of the U.S.-Korean and Sino-Korean alliances. Since it is hard to be accepted, the option Korea can take is to actively seek to establish a multilateral security cooperation in Northeast Asia conforming to the norms of the times, while adjusting the function and role of the USFK maintained in the south of current ceasefire line so that China and Russia can find it acceptable.

The wise strategy at this point is, as President Moon has stressed, to pursue functional and economic cooperations first while continuing the efforts to institutionalize security cooperation. During the Park Geun-hye administration, the Northeast Asia Peace and Cooperation Initiative achieved little success because it singled out and concentrated on functional cooperation in order to build the Northeast Asia multilateral security cooperation. With lessons learned from this, the current government must improve the inter-Korean relationship by building Northeast Asian peace community and providing reconciliatory and humanitarian aids at the same time, induce denuclearization by negotiating corresponding measures on regime guarantee and economic supports, and bring North Korea out of diplomatic isolation by helping them improve the Japan-North Korea relationship.

Hence, the success of multilateral security cooperaton in Northeast Asia depends on whether we can engage North Korea into the international society, solve the nuclear issue, and establish new institutions agreeable to both the United States and China while cooperating with Russia. The South Korean government can be confident about their economic victory in the inter-Korean competition. Hopes are high on them to design forward-looking and creative offers and take initiative to create a multilateral security cooperation in Northeast Asia that can engage North Korea and collaborate with the United States and China.