Reflections on the 70 years U.S.-Korea ‘Ironclad’ Alliance and the Future of the Indo-Pacific


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July 8th, 2023

Figure 1: US ROK Alliance

The Korean War Armistice was signed 70 years ago on July 27, 1953. Geopolitically, Korea and Northeast Asia have not changed much since that date, and the area remains a hotspot in the Indo-Pacific. On October 1, 1953, the United States and the Republic of Korea signed a mutual defense treaty to promote peace and strengthen their collective defense in the Pacific Area. This year marks the 70th anniversary of their historical alliance, which was formed in the aftermath of the Korean War. The alliance has made significant progress in addressing the dangers posed by North Korea’s nuclear threat and China’s increasing assertiveness in the region. The recent addition of the Washington Declaration has further strengthened the alliance.

Consortium’s senior fellow Indu Saxena (IS) talks with its Military History team members on questions to look back over the last seven decades of the alliance and assess the challenges and opportunities of the U.S.- Korea alliance in the emerging Indo-Pacific. Respondents include Christopher Kolakowski (CK), Jose Antonio Custodio (JAC), Brendan Donnelly (BD), and Grant Willis (GW). 


IS: What is the current state of the U.S.-ROK alliance?


BD: The current state of the alliance between the U.S. and the ROK is strong diplomatically, and this is voiced through the Washington Declaration in April 2023. Yet there needs to be a caveat, this alliance is strong when discussing actions and cooperation against the Democratic People’s Republic of Korea, DPRK (aka. North Korea), since deterrence against nuclear proliferation is one of the key focus areas for this alliance. Although, the same cooperation may be hesitant when it is a conflict against China not on the Korean peninsula. This could be the case since in the Indo-Pacific region there are two major “hot spots” the potential conflict over Taiwan and the potential conflict in Korea. For this reason, the alliance is ‘Ironclad’ against DPRK but if the ROK get into a conflict in a Taiwan scenario, they leave themselves open for a second front with their neighbor to the north. It is for these reasons that the U.S.-ROK alliance is a great diplomatic move that may assist in deterring the DPRK but may fall short in deterring the Peoples Republic of China (PRC). Nonetheless, the alliance is still a necessity for both countries in order to effectively operate, and execute their national strategies in the Indo-Pacific region.


JAC: The relationship is as strong as ever before and it may be considered as one of the best military alliances that the United States has with a foreign partner despite the continuous state of war between the two Koreas which automatically draw in their respective allies should it ever go hot again. Even though South Korea was a vastly underdeveloped agricultural based economy when the alliance was established more than half a century ago, it embarked on modernization and since then the country has not been remiss in its responsibilities as an ally of the United States and has moved away from being totally militarily dependent on American might to one that can stand on its own and is considered one of the best in the world. The prowess of the South Korean military was shown in several conflicts from the Korean War to Vietnam. The South Korean defense industry is highly successful and not only provides for the needs of its own military, but also of many others from Asia to Europe. The South Korean government continues and has never wavered to support the presence of US forces in its national territory which creates a powerful deterrent against aggression not only in East Asia but also in the Indo Pacific region.


CK: I agree with my colleagues that the US-ROK alliance is as strong as it has ever been. South Korea remains one of the most important US partners in the Indo-Pacific, and its capabilities have only grown with time. While both partners are correctly focused primarily on threats from North Korea, we should not forget the ROK has supported US efforts elsewhere, including in Vietnam. After seven decades of mutual cooperation, born in the fires of the Korean War, the United States and ROK remain close allies.


IS: How the newly announced “Washington Declaration” can be the instrumental in providing deterrence against North Korea’s growing nuclear ambitions?


BD: The idea of deterrence is complicated since it is not what the U.S. and the ROK do, it is more if the actions performed create the desired effect. An example of this is with the recent combined military exercise Operation FREEDOM SHIELD in March of 2023. Ultimately this exercise is meant to improve the coordination between U.S. and ROK military forces as stated by the United States Forces Korea Command (USFK), but the exercise is also a crucial piece in the deterrence game in showing DPRK the resolve between the two nations.  Even though these coordinated actions between the U.S. and ROK continue we have not seen a decrease in DPRK missile launches or nuclear development. In 2023 alone, the DPRK launched 26 projectiles in the first quarter of the year, 16 of these being during the month of March when the combined exercise took place.  Therefore, the combined exercise seems to not have created the deterrence effect that is wanted by the U.S. and ROK.

Part of the Washington Declaration is for improved combined exercises, and this piece very likely will continuously fail to yield the deterrence the U.S. and ROK are looking for. Although the other piece such as the consultation between the aligned countries and the creation of the Nuclear Consultative Group (NCG) brings in a more diplomatic approach.  Since the military activities are not working the combination of growing diplomatic relations and military cooperation may improve the chances that the DPRK could come to the table. Unless, they feel increasingly threatened by this cooperation, which then could provide the opposite effect and the DPRK instead increase their nuclear proliferation instead. Overall, dealing with a government like the DPRK, the Washington Declaration will likely not deter them from nuclear proliferation, but could be a piece of the puzzle if additional actions outside of the military and diplomatic realms take place.


JAC: The declaration clearly states that the two countries will strive to strengthen their military relations. It is done in a relatively detailed way and not just through motherhood statements and lays out what is to be done to face the primary threat to peace which is North Koreas bellicosity and its nuclear ambitions. It is clear in the declaration that any existential threat against South Korea will be met with the might of America’s own nuclear arsenal. It is a warning against North Korean adventurism and aggression. However, at the same time, both South Korea and the U.S. maintain diplomatic efforts with North Korea to resolve the issue and establish a regime of peace free of the threat of nuclear weapons in the peninsula.


CK: Reading between the lines, the Washington Declaration seems to move South Korea closer to, if not into, the select group of closest US military allies – the so-called “Five Eyes” group of Australia, New Zealand, Canada, and the United Kingdom. (This grouping was in itself a product of World War II and its aftermath.) Moving South Korea into this realm strengthens the American alliance system of the Indo-Pacific, and represents a significant milestone.


That said, I do welcome the openness for diplomacy. The Declaration does not write off any diplomatic options, but does send a definite signal to Pyongyang and Beijing about military preparedness. It effectively strengthens the American alliance without being provocative. Time will tell as to its ultimate effects.


GW: From 27 July 1953 to today the United States and the Republic of Korea (ROK) have enjoyed a sustained level of mutual commitment to deterrence on the Korean Peninsula.  Although an armistice exists between the United Nations Command (UNC) and the Democratic People’s Republic of Korea (DPRK/North Korea), technically, the war has not ended.  Was it a tie, a defeat, or a victory?  The outcome determination is contingent on the goals of the original military intervention of the United Nations led by the United States in June 1950 after the Soviet sponsored North invaded the South.  The survival and current prosperity of the South compared to the Orwellian Marxist Kim dynasty of the North is evidence enough of the righteousness of the UNC’s cause in 1950 and the continued US alliance with the ROK has stood firm ever since. 


The Washington Declaration of 26 April 2023 comes close behind the 70th anniversary of the armistice that ended the official combat between the two sides and President Joe Biden and President Yoon Suk-yeol determined that the shared sacrifice between the allies coupled with the diplomatic and economic commitment to both nations endure as models for promoting peace and good will amongst all nations of the free world.  The declaration commits both the ROK and US to enhanced cooperation in strategic planning and an enhanced ROK conventional role to support US nuclear contingency operations if the North chose the path to a nuclear exchange.  The declaration also stipulates that the ROK has an increased and more direct role within combined tabletop war gaming and planning with US Strategic Command (USSTRATCOM), the nuclear strike arm of the United States Armed Forces which include the missile force, bomber force, and missile submarines.  Becoming more interwoven within the USSTRATCOM environment will allow a further layer of deterrence against any thought of first use or conventional attack by Pyongyang with the firm and clear understanding that both the ROK and US combined commands are politically and militarily committed to a united effort to counter any threat posed by the Kim regime.  USSTRATCOM combined exercises with the ROK means strategic understanding of commander’s intent and a unified response at the strategic level.  This does not disarm the North Korean strategic forces, but it ensures a politically specified response to any nuclear attack from the North.  It provides a clear red line that ensures deterrence, providing a clear road to Pyongyang’s own destruction if the launch of a massive strike is chosen by the Supreme Leader. 


It is essential to note that stated within the joint declaration of 26 April the path to peace and denuclearization is always open to dialogue between the allies and the North without preconditions.  This is an intelligent diplomatic course of action which provides the Kim regime a tool to voice any perceived security concerns from their end while maintaining the necessary avenue to communicate if tensions were to flare up again in a manner like the 2017-2018 crisis period.  Another key aspect of the joint declaration may be to mitigate the risk of a unilateral ROK response to a DPRK provocation, compelling the South to consult with the US prior to any action in response that could avoid bringing the Americans into conflict.   


IS: What are the challenges to the Alliance and what can be an effective strategy to deal with viewing the great power competition in the region?


BD: One of the most complicated challenges with the U.S.-ROK alliance is that when it comes to great power competition, also known to many as extended deterrence, against the PRC it is that the two countries cannot be alone. By this it means that, the U.S. and the ROK must be joined with other partners to include Great Britain, France, Australia, Japan, and the Philippines. Therein lies the challenge. The relationship between Japan and the ROK, notably as two of the most important allies in the region due to their geographic positioning, is the issue.


In 2023 Japan and ROK held their first diplomatic summit in 12 years, and found common ground such as nuclear non-proliferation for the DPRK, maritime access and free trade, and the potential for cooperation to maintain the security of the Indo-Pacific region.  Unfortunately, even though this summit occurred there continues to be multiple instances where the two nations to not cooperate such as environmental actions, and of course military exercises. This issue stems from historic complications from the colonial period up until World War II. As the Indo-Pacific region is known for holding a strong historic memory, these issues between the two nations are difficult to get over and may take time.


The effective strategy, or end goal for the aforementioned nations could be the potential proposal for a North Atlantic Treaty Organization (NATO) like organization in the Indo-Pacific Region called the Pacific Alliance Treaty Organization (PATO). Like in Europe where NATO remains one of the most significant deterrent factors against Russian aggression, the creation of PATO could be the same deterrence.  Even if this international organization was created and no mutual defense agreement was made, it could still deter not only the PRC from acting towards the independence of Taiwan, but could also assist in the nuclear non-proliferation on the Korean peninsula.


JAC: There are no perfect alliances as each have problems of their own which range from military preparedness to socio political cohesion of the member states. Even the internal stability of individual member states have bearing on the alliance as a whole. Fortunately, South Korea has moved away from its troubled past and is one of Asia’s most robust democracies. Meanwhile the U.S. has transitioned away from the problematic and confused messaging of the Trump administration that cast a dark pall on almost all the alliances the country has. If the immediate military threat to South Korea and the U.S. is North Korea, the political threat that may have the capacity to undermine the alliance is embodied by China and its capacity to coopt members of a country’s political elite.  In the long run, China will continue to strive to locate weaknesses in South Korea’s political landscape in order to influence peddle its interests and agenda in the hope of creating a breed of South Korean politicians sympathetic to Beijing. Hence, it is in the interests of the U.S. not to allow a perception to grow that its commitment to its allies and specifically South Korea will waver. China adores a vacuum and the US should never provide one to Beijing.


GW:   Despite the resolute nature of the Washington Declaration by Presidents Biden and Yeol on the 70th anniversary of the signing of the armistice that ended official combat operations on the Korean Peninsula, the question of open conflict reigniting between North and South will continue to plague planners on both sides.  The prospect of conflict remains an almost continuous conversation on media outlets with every new missile Pyongyang launches to demonstrate strength, but the conditions required for the North to renew its goal of conquering the South could spark from many unforeseen scenarios.  The scenario I would like to highlight challenges the alliance within the context of the greater competition posed by both Russia and China in the Pacific. 


If the People’s Republic of China’s (PRC) People’s Liberation Army (PLA) moves to Taiwan by force and the Allies are drawn into conflict, the limited numbers of weapons stocks and availability of forces will be stretched thin.  This will leave the American garrison on the Korean Peninsula more vulnerable to assault and will strain US supply and weapons allocation.  If the North sees an opportunity to move South, despite the nuclear dimension, may be able to catch the Americans off guard.  According to the Center of Strategic and International Studies’ publicized war game titled, the first battle of the next war, simulates weeks of combat between the US led allies and the PRC over an invasion of Taiwan through over 20 simulated wars.  It was determined that without the Korean 2nd front going hot, the Americans ultimately prevailed with significant sacrifice and extreme expenditure of weapons stocks that are difficult to replace.  If the North found an over stretched and low on ammo US attempting to stem the tide in the Western Pacific, the Korean garrison, although reinforced by a massive and capable ROK force, may find itself in perilous situation.  


The likelihood for such a path to be chosen by Kim Jong Un is low due to his assumed goal of survival and continued supreme rule, but the ideological opportunity to force a path South while the United States and the Pacific Alliance is most strained, due to combat operations against the PRC, may provide a once in a lifetime opportunity.  The Washington Declaration should provide much needed strength necessary to deter this scenario while any Western Pacific combat takes place. 


CK: From a regional competition and cooperation standpoint, the biggest issue for the US-ROK alliance may be Japan. The Japanese and South Koreans have much animus because of their fraught history, which hinders cooperation on a variety of issues including defense. It is sometimes said that the two countries have a relationship with each other through the United States.


These tensions have surfaced again in recent years, especially as Japan has embarked on a more robust security strategy. Managing and solving this relationship will be key to regional security, especially as a united front may be needed to counter Russia, China, North Korea, or some combination of the three. There is only so much the United States can do here, and it probably requires a bilateral solution. I am heartened by recent meetings by ROK and Japanese leaders about defense issues, and hope more can be achieved.


IS: Why is the alliance between the U.S. and South Korea consequential for the future of the Indo-Pacific region?


BD: The alliance between the United States and the ROK is consequential for the future of the Indo-Pacific since even though the other nations in the region may or may not have mutual defense agreements, each of them has this type of agreement with the United States. The U.S. has also pledged support to the Taiwanese government as well, therefore, even without PATO, there is a significant combined force that is prepared to respond in the event that the PRC decides to kinetically create ‘One China’ and invade Taiwan. Additionally, this alliance can assist in the deterrence of the DPRK, thus supporting the overall goal of the United States grand national security strategy being to advance international relationships and deter against China.


Without the U.S.-ROK alliance there would be a significant hole in the defense of the free transportation of goods in the Indo-Pacific and in terms of military defense, a significant pocket that the coalition would need if there was an ongoing conflict. These two factors, permit not only U.S. maritime trade within the East China Sea, but for other nations to also transit through these locations safely. Both economic and military interests are supported through this alliance aside from the already discussed diplomatic support as well.


JAC: A strong alliance provides the confidence necessary in maintain a larger global network of alliances especially for the U.S. Should the alliance between South Korea and the U.S. unravel, then it will send shockwaves throughout the international community and will seriously undermine American stature. That will then embolden aggressive countries like North Korea and most especially China to push forward their agenda and in the case of the latter to eventually supplant the US as the preeminent power in Asia. So the alliance keeps the peace, which in turn fosters democratic principles and prevents the Korean peninsula from falling into the pit of nepotistic totalitarian rule. South Korea is an obstacle to unfettered North Korean and Chinese hegemonistic ambitions and plays an equally important role like Japan in the containment of such.


CK: I second all my colleagues’ points and agree that South Korea is a consequential part of the US Indo-Pacific alliance system. The ROK conveys important strategic advantages and assets that are not easily replicated.


The US-ROK alliance matters for one other reason, one Jose touched on to some degree: symbolism. The United States did not abandon South Korea during the Korean War, and still stands on the Korean Peninsula ready to exercise its defense obligations. In several cases during the war, US forces acted to save Korean citizens from the Communists – most notably in the Hungnam evacuation of December 1950. Among those saved at Hungnam was former President Moon Jae-in’s parents, something he never forgot. “Because of the essential humanity of the American military,” he said in 2017, “I do not fear for the future of our alliance.”


These symbols matter a great deal. The Indo-Pacific is a region where memories are long, and actions like Hungnam are remembered and honored even decades later. It should be noted that the South Koreans are not alone in this regard – the Philippines, Japan, Australia, Canada, and many island nations, among others, trace some aspect of their alliance with the US to American actions in World War II and its aftermath. Indeed, the period 1940-1955 is like yesterday in the Indo-Pacific.


Authors Bio:

Christopher L. Kolakowski

Christopher Kolakowski is Director of the Wisconsin Veterans Museum, a reviewer and contributor to the Air Force Journal of Indo-Pacific Affairs, and a Senior Fellow at the Consortium of Indo-Pacific Researchers. He has spent his career interpreting and preserving American military history, and is the author of five books on the American Civil War and World War II in the Pacific.


Jose A. Custodio

Jose Antonio A. Custodio is a security and defense consultant.  He served in that capacity for the Office of the National Security Adviser and the Office of the President during the term of the late Benigno S Aquino III. He also worked for the Armed Forces of the Philippines and was engaged in activities with the then U.S. Pacific Command as a technical advisor. He specializes in military history and has post-graduate studies in history from the University of the Philippines.


Capt Brendan Donnelly

Captain Donnelly is an intelligence officer stationed at Langley AFB, VA. He has held intelligence supervisor roles at Cannon AFB and Special Operations Forces Africa. He graduated Bowling Green State University with a Bachelor of Arts of Sciences, majoring in History.


1st Lt Grant Willis

Lieutenant Willis is an RPA pilot currently stationed at Cannon AFB, NM. He is a graduate of the University of Cincinnati with a Bachelor of Arts and Sciences, majoring in International Affairs, with a minor in Political Science.






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