On the July 27 anniversary of the Korean Armistice Agreement, there were numerous tributes to the ultimate sacrifice so many paid during the Korean War. It was the latest milestone in a year-long campaign to mark the 70th anniversary of the South Korea-U.S. alliance, part of a broader effort to shore up an alliance that has faced numerous challenges in recent years amid an uncertain international environment and former President Donald Trump’s “America First” movement within the United States.
However, before the armistice was ever signed or Washington agreed to enter a mutual defense treaty with Seoul, U.S. officials hoped the collective forces and voices of their fellow United Nations Sending States – the states that fought under the U.S.-led U.N. Command (UNC) during the Korean War – would uphold deterrence on the Korean Peninsula in the future. This little-known aspect of armistice history has increased salience today in a context of worsening China-U.S. relations, advancing North Korean nuclear and missile capabilities, and the need for multilateral partners in upholding an increasingly unstable international order.
Although U.N. Sending States decreased their commitments to the UNC during much of the Cold War, their increasing involvement in recent years indicates growing multilateral support for enhancing security on and around the peninsula. Nowadays, deterrence on the Korean Peninsula is seen almost entirely through a nuclear lens, resulting in increasing nuclear threats and tensions. Finding ways to enhance deterrence through broader multilateral partnerships may offer a less destabilizing method to, if not achieve a formal peace, then at least avoid another conflagration.
UNC Establishment and the “Greater Sanctions Statement”
On July 7, 1950, following two previous resolutions recognizing North Korean aggression against South Korea and recommending U.N. members provide assistance to repel the attack and restore peace on the peninsula, U.N. Security Council Resolution (UNSCR) 84 authorized the United States to establish a unified command made up of U.N. member states and authorized the command to fly the U.N. flag. It was the world’s first attempt at collective security under the U.N. system.
Aside from South Korea, which as host nation provided the largest number of military forces, the United States deployed the lion’s share of forces among the 16 U.N. Sending States. The other sending states included: Australia, Belgium, Canada, Colombia, Ethiopia, France, Greece, Luxembourg, the Netherlands, New Zealand, the Philippines, South Africa, Thailand, Turkey, and the United Kingdom. Five additional states – Denmark, India, Italy, Norway, and West Germany – provided medical or humanitarian assistance to South Korea.
As the conflict stalemated and armistice negotiations began, officials in the Truman administration tried to leverage the U.N. Sending States’ commitment to guarantee South Korea’s future security. Although South Korean President Syngman Rhee pushed hard for a bilateral security treaty, U.S. policymakers believed it was not in the United States’ national interest to negotiate one at that time. Instead, they offered U.S. assistance to bolster South Korean defense capabilities and believed the “Greater Sanctions Statement,” which was approved by the 16 Sending States and was to be released alongside the signing of the armistice, would be sufficient to guarantee Seoul’s security.
The most operative portion of the statement read: “We affirm, in the interests of world peace, that if there is a renewal of the armed attack, challenging again the principles of the United Nations, we should again be united and prompt to resist. The consequences of such a breach of the armistice would be so grave that, in all probability, it would not be possible to confine hostilities within the frontiers of Korea.”
Seoul was first informed of the statement in February 1952. Yet armistice negotiations bogged down for over a year due, among other issues, to intense disagreements about the repatriation of prisoners of war following the war and Stalin’s truculent influence over the negotiating process.
The Armistice and a Mutual Defense Treaty Begrudgingly Given
U.S. President Dwight Eisenhower, who took office in January 1953, had campaigned on a promise to end the unpopular war. Like officials in the Truman administration before him, Eisenhower did not believe the U.S. commitment in Korea was important enough to further expand the war on or beyond the peninsula, but thought that it was too important simply to relinquish. Thus, using threats of nuclear escalation (the effectiveness of which remains unclear) and benefiting from Stalin’s timely demise, Eisenhower pushed armistice talks forward upon entering office. Yet, despite Rhee’s insistence, Washington continued to reject a bilateral security pact with Seoul.
Eisenhower administration officials rejected a mutual defense treaty for a variety of reasons. They feared it would minimize the importance of the multilateral U.N. efforts in Korea and provide legal justification for Communist control of North Korea. Seoul’s own intense, public opposition to the armistice also made it very difficult to explain such a treaty to Congress and the American people. Most important, as Secretary of State John Foster Dulles later confessed, the U.S. did not want to enter such a treaty because it would involve the country in “Asian mainland commitments,” which it would rather avoid.
On May 22, 1953, as late as two months before signing the armistice, Washington offered various measures to bolster South Korean security – in lieu of a mutual defense treaty – in exchange for Rhee’s promise not to disrupt the terms of the armistice. These measures included: the “Greater Sanctions Statement”; initiation of discussions regarding an agreement on future U.S. military assistance; a promise to hold a political conference to achieve Korean unification and withdrawal of Chinese forces from the peninsula; and U.S. support for a 20-division Republic of Korea army.
The next month, Rhee Syngman, for whom nothing could replace a bilateral security pact with Washington, played his hand to the hilt and released thousands of non-repatriated Korean prisoners of war to subvert the armistice talks. While U.S. officials explored plans to overthrow Rhee or withdraw U.S. forces from Korea, they ultimately decided upon a mutual defense treaty as the optimal means of guaranteeing Rhee’s promise not to further disrupt the armistice and institutionalizing hierarchical restraint on their smaller South Korean ally.
UNC Devolution
Furthermore, it was evident that the U.N. Sending States’ interest in maintaining their collective commitment had considerably waned.
Although the “Greater Sanctions Statement,” otherwise known as the Joint Policy Declaration or “Sixteen-Nation Declaration on Korea Issued at Washington,” was released on the same day the armistice was signed, U.N. Sending States quickly reduced or withdrew their combat and medical forces from Korea. By the end of 1956, contingents from 17 of the nations that had contributed forces or medical support had returned to their homelands. By the 1970s, all U.N. Sending States – other than the U.S. – had withdrawn what remained of their much-diminished combat presence.
Following the signing of the armistice, the U.S.-led UNC remained the warfighting command on the Korean Peninsula and was charged with enforcing the armistice. Furthermore, it retained operational control of the South Korean military under the terms of the U.S.-ROK Mutual Defense Treaty. Nonetheless, by the 1970s, the UNC came under significant criticism at the U.N. General Assembly (UNGA). In fact, both China- and U.S.-backed resolutions calling for the UNC’s disbandment passed in the UNGA, and there was internal U.S. planning explore its dissolution.
The UNC was further denuded with the 1978 establishment of the ROK-U.S. Combined Forces Command (CFC) as the warfighting headquarters. The establishment of the CFC shifted responsibility for deterrence and the defense of South Korea from the UNC squarely onto the alliance itself, driven partly by Seoul’s enhanced military capabilities. Although the UNC continued to enforce and maintain the armistice, it was perennially understaffed and given less attention.
UNC Resurgence
This began to change with South Korea’s remarkable economic growth and modernization, the tangible improvement of inter-Korean ties following the June 2000 Inter-Korean Summit, and growing concern about North Korea’s nuclear and missile program. For U.N. Sending States, increasing their participation and staffing in the UNC was one way among others to bolster their involvement with South Korea given its increased attractiveness as a diplomatic partner. For its part, the U.S. increased its attention to the UNC to make sure certain aspects of inter-Korean cooperation did not outpace international sanctions. Moreover, revitalizing the UNC through resurgent Sending State contributions and participation was a way to bolster security and stability through multilateral support.
Over the last 10 years, various sending states, such as Canada, Australia, and the United Kingdom, have increased their personnel and level of engagement with both the UNC headquarters in South Korea and the UNC-Rear headquarters in Japan. In fact, since 2018, successive Canadian, Australian, and British military officers have served as the deputy commander of the UNC. In addition to these countries, the current UNC consists of Belgium, Colombia, Denmark, France, Greece, Italy, Netherlands, New Zealand, Norway, the Philippines, South Africa, Thailand, Turkey, and the U.S., as well as South Korea, the host nation.
Moreover, multiple U.S. four-star commanders of the UNC/CFC/USFK have highlighted the importance of adding multilateral coalition support to the bilateral alliance. U.S. military officers are aware of the need for additional stability in the context of transitioning operational control from the current CFC to a South Korean-led Future CFC (F-CFC), which would not change the command structure but only place a South Korean general as the commander, as well as in the more complex strategic environment in the region, particularly regarding a possible conflict over Taiwan.
To be clear, though, there remain notable challenges.
For one, successive South Korean administrations have looked askance at what was previously referred to as UNC “revitalization,” viewing it either as obstructing inter-Korean engagement or overly restraining the South Korean military from adopting a firm retaliatory posture in response to North Korean provocations. In either case, bolstering the U.S.-led UNC is seen as infringing on South Korea’s sovereignty. Adding greater multilateral contributions similarly piques sensitivities about sovereignty, reinforced by a long history of foreign intervention and meddling by external powers on the Korean Peninsula.
It also did not help that “revitalization” as a term had serious historical baggage. It translates into Korean as Yushin, the name of Park Chung-hee’s 1972 constitution marking the onset of military authoritarian rule within South Korea. It also harkens back to similar terminology used by the Japanese to describe their Meiji Restoration, which Park lionized but helped result in Japan’s colonial rule over Korea.
Furthermore, on the part of the Sending States there remains a lack of clarity regarding formal standing commitments of forces that the UNC or the alliance can count on in a crisis or during wartime. There are open questions about whether Sending State governments would be willing to commit forces to the alliance, having reservations about being “a coalition in support of an Alliance.” Moreover, the U.S. will have to adjudicate how its own continued leadership of the UNC will play out following OPCON transition to a South Korean-led F-CFC. Historically, the same U.S. 4-star general has commanded both.
Moving Forward
Despite these challenges, though, the alliance should seek ways to better operationalize U.N. Sending States’ international military support to South Korea and the alliance. Sending States’ military capabilities, in addition to their diplomatic, informational, and economic influence, are an extremely valuable untapped resource. Leveraging these resources could significantly shape or alter the outcome of a major crisis, not to mention prove invaluable in a conflict and post-conflict Korean Peninsula landscape.
Furthermore, given U.S. budgetary and resource constraints, alongside the possible need to develop a more flexible and distributed force posture in the region, Washington needs greater contributions from Seoul not only on the Korean Peninsula but beyond it. However, Seoul, too, faces significant challenges, not the least of which is an advancing North Korean nuclear and missile threat and pending demographic implosion. The former demands immediate attention, whereas the latter trend will gradually reduce the personnel with which to confront this challenge. In this context, the alliance should seek greater multilateral support for peace and security on the peninsula.
The UNC offers an established and well-institutionalized mechanism and the U.N. Sending States optimal multilateral partners. In addition to enforcing and maintaining the integrity of the Armistice Agreement, the UNC’s priorities include maintaining U.N. Sending State and Participating Nation cohesion and international support for South Korea-U.S. alliance activities; maintaining access to UNC-Rear bases in Japan; and establishing efficient procedures to coordinate Sending State force flow and force generation in coordination with the South Korean Joint Chiefs of Staff to support and sustain those forces in theater in the event of a crisis or conflict.
To navigate the challenges in modernizing the UNC, South Korea should take greater ownership of the process, consistent with its enhanced profile as a “global pivotal state.” The effort must be properly and consistently explained to the South Korean public, with the full support of the United States. Seoul should expand its staffing at the UNC headquarters directly, rather than through the CFC. It should also continue to bolster its already burgeoning military and defense cooperation with various U.N. Sending States and look for opportunities to run exercises and training with them, capitalizing on the fact that in recent years various Sending States that are party to the U.N.-Japan Status of Forces Agreement have increased the frequency with which they rotate forces through the seven designated U.N. bases in Japan.
In the context of preparing for wartime OPCON transition, South Korea should also take greater ownership of the UNC given the fact that leading the alliance’s combined command will require a much firmer grasp of coalition operations, which are integral for flowing both U.S. and U.N. Sending States’ forces to the peninsula. Lastly, taking greater ownership of the UNC will require continuing to improve relations with Japan, considering the crucial role that UNC-Rear HQ and the seven designated U.N. bases in Japan would play in any contingency or conflict on the Korean Peninsula.
Starting in the mid-2010s, some Sending States integrated military forces into CFC training and exercises, notably the twice-yearly CFC theater-level command post exercises held in the late winter and late summer. During such exercises the UNC’s Multinational Coordination Center (MNCC), organized in 2008, played an active role in facilitating the participation of Sending States. For example, Australia, Canada, Denmark, France, and the United Kingdom participated in the 2015 Key Resolve combined command defense exercise.
Starting in 2016, the MNCC became a facilitator of multinational planning and coordination for the UNC outside of exercises. The alliance and South Korea should find ways to reenergize the MNCC, further include Sending States in alliance military exercises, and bolster the South Korean Joint Chiefs of Staff’s relationship with the MNCC.
During recent Warrior Shield combined exercises, Washington and Seoul sent mixed signals about the involvement of UNC personnel. It is time for the alliance to move beyond such divergent messaging. Ongoing talks about UNC modernization indicate that this effort is underway.