Why South Korea Wants Nuclear Weapons Now More Than Ever

To the horror of many South Koreans, Donald Trump has returned to the White House. No one, including perhaps President Trump, knows what he ultimately hopes to achieve on the Korean peninsula, but his rhetorical war on NATO offers a dire warning for the Republic of Korea.

Trump already has indicated that he wants the ROK to contribute more—$10 billion annually—toward the deployment of U.S. troops in South Korea. That request is not likely to be received warmly in Seoul. To start, that would mean tearing up the agreement South Korea reached with the Biden administration.

General view during the test firing of what state media report is a North Korean “new type” of intercontinental ballistic missile (ICBM) in this undated photo released on March 24, 2022 by North Korea’s Korean Central News Agency (KCNA). KCNA via REUTERS

One doubts that there will be any karaoke rounds when Trump meets whoever ends up as president of the ROK if Yoon Suk-Yeol is ultimately removed from office.

South Korea’s Nuclear Weapons Pursuits

Concern over the Trump administration could have a more profound impact on the alliance than just an argument over money.

Shortly after Trump’s victory, South Korean political analyst Cheong Seong-chang declared: “The reelection of Trump is an opportunity for South Korea to create its own nuclear weapons.” Cheong, who formed the ROK Forum for Nuclear Strategy, which promotes South Korea developing its own nuclear deterrent, explained that “mistrust of the U.S. is growing.” His argument looks more prescient after Trump’s inauguration.

Mason Richey from Hankuk University of Foreign Studies made a similar point: Interest in nuclear weapons “will be significantly affected by how the Trump administration approaches the alliance with South Korea and how it approaches the relationship with North Korea.” Trump denigrating the bilateral alliance and “wanting to reach an arms control deal with North Korea that provides Pyongyang with nuclear weapons status,” Richey said, will increase the ROK’s interest in “obtaining its own nuclear weapons.” 

There long has been a popular majority in favor of South Korea producing its own deterrent. A June survey found two-thirds in favor; that proportion recently reached as high as 76 percent. Critics complain that the simple yes/no question ignores the issue’s complexity, including the political and economic costs of going nuclear. The share of “strategic elites,” as a recent CSIS report labeled them, who support development of nuclear weapons is only about half as great.

Explained CSIS: “The main reason South Korea’s strategic elites do not favor nuclearization is the consequences in terms of international condemnation, reputational costs, and sanctions, highlighting the value that elites place on South Korea’s global status in the rules-based international order.”

However, there was a notable condition. More than half of those expressing opposition said they could change their position in response to the rise of “abandonment fears regarding the United States, attendant with policies that denigrate allies and call for troop withdrawals.” Nine of 10 supporters of nuclear weapons said such a development would increase their backing. CSIS cited belief in the alliance as the most significant factor in support levels, warning that “the return of Donald Trump to the White House and a renewal of decoupling rhetoric or actual policies to withdraw U.S. ground troops from the peninsula could significantly impact the nuclear debate in South Korea.”

Nuclear Movement

Trump’s election cannot help but reinforce South Korean fears about the volatility of American politics. After all, Trump no longer can be dismissed as an accidental president elected by the Electoral College rather than the American people. He won the popular vote this time, and he did so running against an administration that prided itself on its handling of foreign policy. With a Republican-controlled Congress, Trump will have wide latitude in shaping U.S. foreign policy. And his behavior toward Europe demonstrates that he means to make radical changes.

South Korean interest in building an atomic bomb goes back to the 1950s. President Park Chung-hee set the goal of developing a weapon by 1977, but abandoned the program under strong U.S. pressure. North Korea’s program reignited ROK interest in creating a deterrent. In January 2023, South Korean President Yoon Suk-yeol cited the North Korean nuclear threat, suggesting a return of American tactical weapons, or, “if the issue becomes more serious, we could acquire our own nuclear weapons.”

U.S. policymakers have consistently reacted in horror at the prospect of a South Korean bomb. Yoon’s office insisted that there had been no change in South Korean policy, but his comment spurred the Biden administration’s efforts to reassure Seoul that it would indeed risk U.S. cities to save Seoul. At the April 2023 Biden-Yoon summit, Washington piled higher and deeper the arguments and proposals promoting extended deterrence. Central to the meeting was the Washington Declaration, reaffirming the administration’s nuclear commitment to the South. The U.S. offered more meetings and consultations, while refusing to approve formal nuclear sharing. Then-Deputy Secretary of State Kurt Campbell explained “that the mechanisms that we’ve put in place … the Washington Declaration and the strategic initiatives that have been launched to underscore the added signification of American extended deterrence, particularly in situations like Korea, I think it’s given us what we need to work with now.” However, Biden insisted that only he would be responsible for any decision to use nuclear weapons.

Despite these efforts, a number of primarily conservative politicians have discussed or endorsed South Korea developing an indigenous weapon. Burgeoning military cooperation between Moscow and Pyongyang, with the possibility of Russian support for North Korean nuclear and missile programs, has raised political temperatures further. Allison Hooker, who served on the Trump National Security Council staff, warned: “I think we cannot rule out the fact that South Korea continues to move, maybe more rapidly, towards its own nuclear program.” If a progressive wins an election to replace Yoon, as seems likely, the government is more likely to oppose the idea. But changes in U.S. policy might force even the South Korean left to reconsider its position.

The Main Argument

Discussions of the issue almost always focus on Seoul’s decision. Would it make sense for the ROK to develop nuclear weapons?

The arguments against it are obvious and many—the cost, the impact on the U.S. alliance, the potential for sanctions, possible damage to the nuclear energy industry, the possibility of triggering a Japanese program in response, the effect on relations with China, and the potential North Korean response.

There is one major counterargument: the diminishing reliability of Washington’s promise to risk American cities for Seoul. That assurance sounded good to both sides when North Korea had no means to retaliate against U.S. territory. The promise looks much less reliable as the North develops that capacity. There is no reason to assume that Pyongyang won’t succeed, especially if Moscow lends a hand. And with America arming Ukraine to kill Russian soldiers, Vladimir Putin might have done so. Under these circumstances, would Washington live up to its promise?

Yoon has acknowledged: “What we call extended deterrence was also the U.S. telling us not to worry because it will take care of everything, but now, it’s difficult to convince our people with just that.” Solemn promises are cheap. Angry Ukrainians cite the assurances contained in the Budapest Memorandum, which encouraged them to yield their Soviet-era nuclear weapons. Alas, there was no enforcement of any security assurances attached to Budapest, and the Washington Declaration provides no better guarantees. Perhaps for this reason, Cheong says the ROK shouldn’t even ask America to take this risk. “We cannot expect—and should not ask—the American president to use his nuclear weapons to defend an ally at the risk of sacrificing his own people.” 

For the first time, more South Koreans favor developing a nuke than preserving U.S. troop presence. Left out of this discussion, however, is the most important question, from Washington’s standpoint. Why should the U.S. prefer exercising extended deterrence over the ROK to an independent South Korean deterrent? Robert E. Kelly of Pusan National University and Min-Hyung Kim of Kyung Hee University argue that it should not: “American opponents of South Korean nuclearization exaggerate the policy’s downsides, underappreciate its benefits, and ignore the United States’ own liberal values that call for Washington to tolerate a democratic partner’s national security choices, even when it dislikes them.”

The Burgeoning Risk to the U.S.

Of course, the U.S. typically claims the dominant role in any defense relationship. That made sense in Korea during the 1950s, when the South lagged behind the North. But the case for an American conventional defense of South Korea disappeared long ago. South Korea possesses an economy more than 50 times that of the DPRK, and a population twice as large. The ROK has a vast technological lead and far stronger diplomatic network. In distress, Seoul could call on most of the industrialized world for support, while Beijing almost certainly would not support a North Korean attack on South Korea. Nor would Russia, despite the latter’s new relationship with the DPRK.

With an independent nuclear deterrent, South Korea could deter Pyongyang from using nukes offensively. That is a far better option than the U.S. having to do so. Defenders of the status quo respond that America has nothing to fear, since North Korea wouldn’t dare use its nukes. But Pyongyang’s weakness in a conventional contest would leave it little choice but to threaten a nuclear response to a conventional American attack. If deterrence failed, it would have no reason not to spread the doom, like the Israelite warrior Samson.

The burgeoning risk to America is causing U.S. analysts to question the long-term viability of the alliance with South Korea. The Hoover Institution’s Michael Auslin has called out the importance of the growing DPRK threat: “While few believe Kim Jong Un would launch an unprovoked nuclear strike, most seasoned Korea watchers believe that he would no doubt use his arsenal once it became clear he was about to lose any war that broke out. As this risk increases, Washington will find it increasingly difficult to avoid reassessing the country’s multi-decade alliance with South Korea. The threat to American civilians will be magnified to grotesque proportions, simply because Washington continues to promise to help South Korea.” 

How long can such a situation last?

Proliferation may not be desirable, but it is better for Americans not to risk their society to defend non-nuclear states. America’s economic and cultural ties with the ROK are substantial, but not existential. During the Cold War, Washington could brandish nuclear weapons against North Korea without consequence, since the latter could not respond in kind. No longer—North Korea is preparing to join the small band of nations that have the ability to incinerate American cities. And nothing at stake on the Korean Peninsula warrants the sacrifice of American cities and potentially millions of Americans.

Of course, every breach of the global nonproliferation standard is undesirable. However, North Korea has already broken its pledge, and the U.S. has encouraged, accepted, or accommodated proliferation elsewhere. No sanctions were applied against the United Kingdom, France, or Israel. Washington tried, but failed, to prevent India and Pakistan from joining the nuclear club and eventually accepted the new reality. South Korea’s entry would only reinforce past breaches.

Times Are Changing

The issue of a South Korean bomb takes on special significance now, since the Trump administration might be more open to the possibility. For instance, former Pentagon official Elbridge Colby, who is set to become undersecretary of defense for policy, observed early last year that while friendly proliferation is undesirable, “we live in a world of hard choices, so I think everything needs to be on the table.” Mike Pompeo, CIA director and secretary of state during Trump’s first administration, contended that, “There’s no reason we should object to” such a development. Most important, when he first ran for office, Trump noted that, “Unfortunately, we have a nuclear world now,” so it “may very well be better” if South Korea and Japan also had nukes when facing North Korea.

Hwasong-17 North Korea ICBM. Image Credit: North Korean State Media Release.

Few Korea analysts welcome a second Trump presidency. However, his willingness to engage Kim six years ago demonstrated creativity and courage, as well as a readiness to abandon longstanding policies that had failed. New approaches are even more necessary now. Almost no one believes that Kim is prepared to disarm, irrespective of Washington’s threats and inducements. Eventually the U.S. will have to reconsider its defense of South Korea, since any war there could result in destruction here. Even a small risk of Armageddon is too great to justify Washington’s defense of a country capable of arming itself.

Seoul and Washington will have little choice but to enter into serious negotiations about all aspects of the alliance. The peninsula’s nuclear future should be high on the list of topics. Extended deterrence is losing credibility on both sides of the Pacific. What is to follow? That needs to be decided soon.

About the Author: Doug Bandow

Doug Bandow is a Senior Fellow at the Cato Institute. A former Special Assistant to President Ronald Reagan, he is author of several books, including Tripwire: Korea and U.S. Foreign Policy in a Changed World and co-author of The Korean Conundrum: America’s Troubled Relations with North and South Korea.