Is the US-ROK Alliance Prepared for a Multipolar World?

In the seminal 1979 classic Theory of International Politics, Kenneth Waltz identified the benefits a state can derive if its security is underwritten. According to Waltz, if security is assured, a state can: “safely seek such other goals as tranquility, profit, and power.”[1] South Korea is an example of exactly that. From the ashes of the Korean War that raged on from 1950 to 1953 and the subsequent seven decades to follow, the United States-Republic of Korea (US-ROK) alliance has fostered an atmosphere of sustained peace and stability that has contributed to the ROK’s successful political and economic transformation. Today, South Korea stands among the world’s most productive and prosperous countries.

The US-ROK alliance recently commemorated two significant milestones this year: July 27 was the 70th anniversary of the armistice agreement, and October 1 marked 70 years since the signing of the US-ROK Mutual Defense Treaty (MDT). Another important milestone is set to occur this November 7, which is the 45th anniversary of the establishment of the Combined Forces Command (CFC)–the structure through which the alliance demonstrates US-ROK preparedness to deter threats and defend against a resumption of hostilities on the Korean Peninsula. Together, these instruments of the alliance have unassailably guaranteed South Korea’s security, which in turn has helped to ensure peace and stability in Northeast Asia.

For all that the alliance has done to ensure peace and stability over the past seventy years, Northeast Asia is still one of the toughest neighborhoods in the global system. The region is geographically dominated by China and Russia, both of which are calling for an alternative to a US-led order, and North Korean leader Kim Jong Un recently joined the two countries in solidarity with his own calls to stand “against the US and the West’s strategy for hegemony” while boosting production of nuclear weapons. In the context of Northeast Asia, the newly emerging and increasingly nuclear China-Russia-North Korea bloc imperils South Korea, which has depended on its alliance with the US to ensure its security. The US-ROK alliance will be put to a new test in an increasingly multipolar order, but can effectively handle this new challenge by adhering to the principles and structure upon which it was built.

Challenges in a Changing World

For all its sustained success and longevity, the alliance’s greatest challenges still lie ahead. While South Korea has thrived under a US-led global system that accelerated after the US “unipolar moment“ began at the end of the Cold War, the current global system is fraying. It should be clear to even the most casual observer of foreign affairs that today’s global reality is in stark contrast to the US vision of a world embarking upon a “new age of liberty,” as described in September 1991 by George H. W. Bush in his address to the UN General Assembly.

Today, more than thirty years after the US-led neoliberal transition from the bipolar Cold War order began, the world is again experiencing conflict and shifts caused by competing centers of geopolitical power to a degree that has not been seen since World War II. The drift toward multipolarity is blatantly manifested by converging objectives within the respective China-Russia-Iran perceived spheres of influence and directly challenges the remaining US-led international order. As a result, US foreign policy is becoming increasingly distracted with wars now raging in Europe and the Middle East, and the potential for conflict still looms over the Taiwan Strait.

In Northeast Asia, Kim Jong Un’s budding partnership with Vladimir Putin–Xi Jinping’s “dear friend“–brings the reality of a China-Russia-North Korea axis to the region. The fact that this nuclear-armed triumvirate now surrounds South Korea also means it is positioned against the US-ROK alliance. Besides the obvious nuclear threat this triumvirate presents, there are additional foreign policy dilemmas that South Korea must grapple with. For example, the elephant in the room is its trade relations with China, as South Korea’s trade volume with China remains nearly double that of its trade with the US and is roughly four times greater than its trade with Japan. Although the ROK remains dependent on stable trade relations with China, the People’s Republic of China (PRC) maintains coercive military pressure on South Korea.

The PRC has increasingly applied military pressure on South Korea through joint military exercises with Russia via both naval drills and air operations that include unannounced bomber and fighter aircraft intrusions into the ROK’s air defense identification zone. Moreover, there is speculation that China and Russia will invite the Democratic People’s Republic of Korea (DPRK) to participate in their next annual joint naval exercise, which is likely to be held in the East or West Sea of Korea in July of next year. For its part, North Korea has already established itself as a weapons supplier to Russia’s war effort with Ukraine, and there are suspicions that the DPRK may have supported Hamas with arms used in the October 7 attack against Israel. For South Korea, these moves require a diplomatic juggling act that not only addresses its security concerns, but also maintains its economic relations in the region while managing domestic affairs.

Navigating Diplomacy and Internal Politics

To its credit, South Korea has demonstrated a degree of skill in managing diplomacy with China and the US while keeping threats in check. The Yoon-Biden era of the alliance has produced a string of successes, including the creation and implementation of a strategic alignment on policies for preventing China from changing the status quo in the Indo-Pacific region. In addition, the ROK’s President Yoon’s diplomacy push with Japanese Prime Minister Fumio Kishida in the first half of 2023 led to the August formalization at Camp David of a new US-ROK-Japan trilateral partnership. Yoon’s policies have also improved the operational effectiveness of the alliance, as seen through this year’s normalization of the Terminal High Altitude Area Defense (THAAD) missile defense system after years of delay during the previous Moon administration.

Despite the recent successes and built-in assurances to the alliance, the majority of South Koreans, regardless of political affiliation, want their own nuclear weapons, which should not come as a shock. North Korea has not only dramatically accelerated its missile launches in recent years but has also increased its production of atomic weapons and upgraded its nuclear doctrine to an offensive posture of preemption. Presidents Biden and Yoon have responded through the Washington Declaration, with the US recommitting to extend its nuclear deterrence to South Korea, the ROK reaffirming its commitment to the Nuclear Nonproliferation Treaty, and both countries agreeing to establish a Nuclear Consultative Group so as to strengthen US guarantees of extended deterrence.

Notwithstanding the exemplary alignment of the US-ROK alliance under the current Biden-Yoon administrations, there exists in both countries the potential for politics to turn on a dime.

With each election, the political pendulum swings wide from the left to the right and back in both countries, and these perennial shifts often create policy combinations that place stress on the alliance. The strains caused by discordant policies have even caused uncertainty over the future direction of the alliance. Examples abound from nearly every administration since Eisenhower, with the most recent occurring during the Moon-Trump administrations. Moon delayed timely operationalization of the THAAD system while former President Donald Trump threatened to pull US forces off the peninsula as he applied pressure on South Korea to increase its portion of defense cost-sharing.

The internal political dynamics of the ROK and US will likely continue to create policy dilemmas for the alliance to sort out in future administrations. However, as Sino-Russo revanchist objectives have come into alignment, policy rifts that have been smoothed over or waited out in previous US and ROK administrations could be more problematic as China-Russia-North Korea will collaborate assiduously to exploit fissures in US-ROK relations. Indeed, an increasingly multipolar world beset by a China-Russia-North Korea collaboration is an inescapable reality for Northeast Asia, and this calls into question whether or not the alliance is prepared to encounter this reality.

Preparing for an Uncertain Future

Multipolar challenges to the current global order will undoubtedly create uncertainties across the geopolitical landscape. While the US-ROK alliance has operated successfully since the end of the Korean War through bipolar and unipolar epochs, its effectiveness in a multipolar context is untested. In the regional context of Northeast Asia, the US-ROK alliance must not only continue to deter the North Korean threat but must also defend against an emerging China-Russia-North Korea bloc that seeks to revise the US-led order. We can, therefore, expect geopolitical competition to increase in Northeast Asia and presume that a nuclear-armed, offensively oriented North Korea will attempt to benefit in a revised order and will do its part to help shape it, while politics both within and between the US and ROK will continue to shift. If history serves as a bellwether, minor adjustments to the US forces’ footprint in Korea could occur, and there is no telling as to what extent recently enhanced ROK-US-Japan trilateral relations will continue to hold up.

Considering the challenges presented above, the keys to ensuring South Korea’s sustained peace and prosperity will be the very principles and structure upon which the US-ROK alliance was built. As the legal premise for the alliance, the MDT not only enshrines a US commitment to safeguarding the defense of the ROK, but also contains provisions that address responding to any potential aggressor in the region on either party to the agreement. The Armistice agreement continues to serve as an enforceable mechanism for the United Nations Command to ensure stability on the Korean Peninsula by facilitating diplomacy with North Korea and actions that can lead to lasting peace. Finally, in the event of a contingency, the alliance is equipped with a bilateral ROK-US command structure through the CFC that is fully integrated to the tactical level and honed through combined planning, training, and exercises.

In sum, as the realpolitik of an increasing China-Russia-North Korea collaboration sets in against the backdrop of Sino-Russo revanchism and the DPRK’s offensive nuclear doctrine, the US and South Korea must maintain alliance effectiveness through strong adherence to the MDT and the Armistice agreement and by demonstrating unfaltering readiness through the CFC. In this way, South Korea can continue down a prosperous path in a stable Northeast Asia while the US-ROK alliance works to deter and safeguard against all regional threats.

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