The bilateral military alliance between South Korea and the United States has become increasingly unproductive and needlessly perilous for both countries. Astute American analysts have argued for decades that the arrangement is not a good deal for the United States. The Republic of Korea (ROK) has been one of the most blatant security free-riders among Washington’s roster of “allies”—or more accurately, Washington’s clients and dependents.

U.S. officials have repeatedly pressed South Korea to spend more on its defense and pay a greater share of costs for U.S. forces stationed on the Peninsula. Such complaints became especially pertinent when the ROK emerged as one of Asia’s “tigers,” vastly outstripping communist North Korea as an economic player and becoming fully capable of boosting its defense budget.

U.S. critics also questioned the wisdom of having the United States remain on the front lines of the confrontation between North and South Korea. Such a security shield may have made sense during the height of the Cold War, when both U.S. leaders and the American public saw Pyongyang as one component of a dire, global communist threat. Once the Cold War ended, though, that rationale became utterly obsolete. Americans are now incurring grave risks to deal with a parochial struggle between the two Koreas. Worse, North Korea is fast acquiring the capability to launch nuclear strikes against the American homeland, boosting the level of risk to horrific levels.

It is easy to see why the bilateral alliance is an increasingly bad deal for the United States. In more subtle ways, though, it is becoming a very bad deal for the ROK. U.S. leaders could adopt a rash, aggressive policy toward Pyongyang and needlessly entangle South Korea in an avoidable war. That point became glaringly apparent when Bill Clinton’s administration seriously considered launching air strikes to eliminate North Korea’s embryonic nuclear weapons program. Fortunately, administration officials backed away from the abyss, but South Koreans realized that they could do nothing if Washington decided to use military force—despite the potentially catastrophic consequences to their country.

Uneasiness in the ROK surged again in 2017 when the Donald Trump administration engaged in a saber-rattling confrontation with North Korea. Sentiment has been growing for years among South Koreans to reduce their country’s dependence on the United States. One manifestation is the gradual escalation of domestic support for building a nuclear arsenal rather than relying totally on Washington’s extended deterrence guarantee.

An independent South Korean (or Japanese) nuclear deterrent has always been anathema to U.S. policymakers. That position became especially clear with the April 2023 summit between President Joe Biden and ROK President Yoon Suk-yeol. The joint declaration at the conclusion of the summit confirmed that Seoul would not pursue an independent deterrent. In exchange, Biden promised an even more robust U.S. commitment to South Korea’s security, including the symbolic gesture of sending a nuclear submarine to dock in the ROK for the first time since the 1980s. Biden also indicated that Seoul would have greater input into decisions involving the bilateral alliance, including nuclear policy.

Nevertheless, ROK leaders and the Korean people have reason to be wary about Washington’s broader motives and behavior. Seoul continues to value the bilateral alliance as essential protection against aggression from North Korea. Washington’s primary objective, though, has become to enlist Seoul in a regional containment policy directed against China.

More than a few examples of suspicion and discord have begun to emerge between the two allies because of such a crucial difference in priorities. Yoon’s predecessor, Moon Jae-in, firmly resisted Washington’s insistent lobbying for an anti-PRC policy. When he first took office, Yoon was widely expected to be more hardline toward China and pro-U.S. Instead, the trajectory of South Korean policy toward the PRC has not changed much. Seoul still wants to avoid antagonizing Beijing regarding either economic decoupling or Taiwan—both top priorities for Washington. China is a major ROK trading and investment partner, and Seoul wants the PRC to discourage North Korea from engaging in rash actions.

As Cato Institute senior fellow Doug Bandow points out, Seoul especially has major incentives not to antagonize Beijing militarily. “South Korean military facilities would be targeted by Chinese missile attacks to prevent their use by U.S. forces. If Seoul and other allied states committed to war on Washington’s command, Beijing would have an incentive to strike preemptively if conflict loomed.” That reality largely explains Yoon’s refusal to make a firm commitment to Washington regarding policy toward Taiwan, North Korea, missile deployments, or other security issues that could lead to a collision between the ROK and the PRC.

Indeed, Seoul has gone out of its way to emphasize independence from the United States even on purely symbolic measures pertinent to China. When House Speaker Nancy Pelosi made her trip to East Asia in August 2022 in an ostentatious display of U.S. support for Taiwan, Seoul’s reaction was not merely cool, but frigid. Not only did Yoon decline to meet with her (asserting that he was on vacation), but there was no official ROK delegation to meet her at the airport—a blatant snub. Several stories also leaked to the South Korean press during that period that the United States would not be allowed to use its bases in the ROK for any military action against the PRC if a conflict flared over Taiwan.

A strategic divorce between the United States and South Korea has become essential. America is needlessly incurring a risk of nuclear destruction to protect the ROK from North Korea—even though Seoul is fully capable of building whatever defense forces are needed. At the same time, South Korea is incurring a needless risk of being dragged into a U.S.-initiated war against Pyongyang or into a regional war between the United States and China. The bilateral alliance does not serve the best interests of either the ROK or the United States.