The alliance between the United States and South Korea (Republic of Korea) is a cornerstone of the U.S. security architecture in the Indo-Pacific and, increasingly, in the world. Both the United States and South Korea must do all they can to strengthen this vital alliance.

As this year marks the seventieth anniversary of the alliance, with an upcoming state visit of President Yoon Suk-yeol to Washington later this month, it is important to appreciate the historical significance of the alliance.

For South Korea, the alliance has been the guarantor of its security and the bedrock of its economic development and prosperity since the Korean War. For centuries, Korea had been under the suzerainty of China and its fate had been tied to that of its Chinese overlords. As the Chinese empire declined in the late nineteenth century and collapsed in the early twentieth century, so did the old dynastic rule in Korea.

As Korea fell under Japanese colonial rule for thirty-six years, it was the United States that played the greatest role in liberating Korea from Tokyo’s grip at the end of World War II. And when communist forces overran South Korea in 1950 in the Korean War after Korea’s division, the United States spearheaded the United Nations forces dispatched to repel the invasion. Though the UN forces failed to reunify Korea, they preserved the territorial integrity of South Korea in large measure.

The U.S.-ROK alliance, cemented in 1953 at the end of the Korean War, marked a historic shift in Korea’s fate. For the first time in Korea’s history, a Western democratic great power came to be the principal ally and security guarantor of a Korean state. With its fate tied to the United States, South Korea came to experience miraculous economic development and an impressive transformation into a mature industrialized democracy.

For the United States, the U.S.-ROK alliance has been indispensable in preserving and defending the rules-based international order in the Indo-Pacific since the Korean War.

As the Indo-Pacific now contributes the largest share of the global population and the global economy, it is arguably the most important region of the world for U.S. national security and prosperity. However, the rules-based international order in the Indo-Pacific faces grave threats from Beijing’s expansionism and Pyongyang’s nuclear proliferation.

Although defending the rules-based international order in the Indo-Pacific is crucial for U.S. national security and prosperity, there is no NATO-like collective security mechanism in the Indo-Pacific to stem forces of autocracy. In the absence of a collective security mechanism, what Washington has put together is an uneven patchwork of bilateral alliances and cooperative arrangements with individual countries. In this less-than-optimal security architecture, the linchpin is the U.S.-ROK alliance, along with the U.S.-Japan alliance.

Other than the U.S. alliances with Japan and Australia, the U.S.-ROK alliance has been the only enduring bilateral alliance for Washington in the Indo-Pacific. Other U.S. alliances in the Indo-Pacific such as the Southeast Asia Treaty Organization did not endure, and the United States has only a few reliable allies in the Indo-Pacific, as numerous Indo-Pacific nations have been neutral or leaning toward Beijing in the standoff between Washington and Beijing.

The geopolitical and geostrategic importance of the Korean Peninsula cannot be overstated. Located within close proximity between Beijing, Tokyo, and Vladivostok and with substantial U.S. forces stationed in Japan and South Korea, it is the only place in the world where the national security and interests of China, Japan, Russia, and the United States—four of the world’s greatest powers—directly intersect in a visceral way.

South Korea’s importance as a key ally of the United States has been demonstrated over the decades since 1953. In the Vietnam War, for example, Seoul sent massive numbers of troops to fight in Vietnam alongside U.S. troops.

Today, South Korea is increasingly a key U.S. partner in defending the rules-based international order. As a leading trading nation with an export-based economy that is heavily dependent on the import of energy and raw materials from abroad, South Korea’s security and prosperity depend on the integrity of the rules-based international order, including the freedom of navigation in the high seas where its exports and imports are in transit.

Seoul’s importance to Washington has increased even more in recent years, as South Korea has become one of the largest advanced industrialized democracies in the world with a global leadership in key strategic industries such as semiconductors and electric vehicle batteries. With a military rated as the sixth most powerful in the world, South Korea today has become a major arms exporter, with its military hardware supplying nations including Poland and Australia. Seoul now has troops stationed in nations including the United Arab Emirates and is a regular contributor to international peacekeeping activities.

All this has resulted in a major upgrade of the U.S.-ROK alliance, with the partnership now expanding from the military sphere into economics and technology. Last year, South Korean firms invested billions of dollars in the United States, seeking to build factories in states ranging from Georgia to Ohio to Texas.

Given all these developments, South Korea today is undoubtedly among the most pivotal key allies of the United States, and Seoul has arguably become as important to Washington as Tokyo. Considering this seminal importance, what can be done to protect and further enhance the alliance?

For its part, Washington must refrain from taking measures that damage the national image of the United States and turn South Korean public opinion against it. The U.S. Inflation Reduction Act recently is an example of such measures, as it contains provisions favoring electric vehicles made in the United States over those made overseas. Such discriminatory measures that are seen as promoting U.S. economic interests at the expense of the interests of U.S. allies including South Korea do much more harm than good to the U.S. national interest. Such measures must be avoided if the United States were to protect its crucial alliances with key partners such as South Korea.

Washington must bear in mind that China is keen to capitalize on tensions between the United States and its key allies such as South Korea. Washington must realize that damage to its alliance with Seoul can push the latter closer to Beijing. Washington must understand that Seoul moving into Beijing’s orbit would devastate U.S. credibility and leadership in the Indo-Pacific and indeed around the world.

For its part, Seoul must recognize that its future survival and prosperity hinge on the alliance with the United States and therefore strengthen its ties with Washington. While South Korea needs to maintain good relations with China, its biggest trading partner and a key stakeholder in addressing challenges posed by North Korea, Seoul must guard against Beijing’s attempts to drive a wedge between it and Washington. Seoul must realize that, if it allows its relationship with Washington to deteriorate excessively, it could fall back under Beijing’s suzerainty as it used to be for centuries.

Clearly, the seventy-year-old U.S.-ROK alliance is critical to the national interests of both nations and is among the cornerstones of the rules-based international order. Both Washington and Seoul would be wise to refrain from taking steps that damage this alliance, and they would be wise to guard against attempts by third parties such as Beijing to undermine this alliance. Under careful stewardship, this key alliance will help guarantee continued security and prosperity in the Indo-Pacific and around the world for many years to come.

Jongsoo Lee is Senior Managing Director at Brock Securities and Center Associate at Harvard University’s Davis Center for Russian and Eurasian Studies. He is also Adjunct Fellow at the Hawaii-based Pacific Forum and Contributing Editor at The Diplomat. He can be followed on Twitter at @jameslee004.

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