The Folly of Deploying US Tactical Nuclear Weapons to South Korea

The mudslinging between US President Trump and North Korean leader Kim Jong Un and the near-daily handicapping of whether the US and North Korea are bound for war have overshadowed an important debate in South Korea over whether the US should redeploy tactical nuclear weapons (TNW) on ROK territory. Proposals that US government officials and defense experts have floated to ease South Korean worries about the credibility of the US extended deterrent have primarily focused on bolstering US/ROK conventional defenses against North Korean aggression. These measures, while necessary in the short-term, may not be sufficient to contain South Korean pressure for either US TNW deployments or development of an indigenous nuclear weapons program over the long-run, especially if the conservative party returns to power. If Washington wants to keep the South Korean nuclear genie in its bottle, the administration may need to draw the ROK more closely into US nuclear planning for the peninsula and elevate the visibility of its own nuclear footprint in and around the country. But this path should only be taken if the US is ready to simultaneously take diplomatic initiatives with North Korea to prevent misperceptions and potential escalation.

(Photo: Uriminzokkiri)

It is difficult to predict the outcome of the South Korean debate over its nuclear future. President Moon is adamantly opposed to the re-introduction of TNW and to South Korean development of nuclear weapons—and his views are likely to prevail as long as his party stays in power and he remains committed to pursuing improved relations with China and dialogue with North Korea. However, the call for the redeployment of TNW began in 2013 and has steadily grown louder and stronger as North Korea’s nuclear capabilities have improved—for the past year, the South Korean opposition party has mounted a full-court press on the Trump administration to return TNW to South Korea, which were withdrawn in 1991. In a recent trip to Washington, Hong Joon-pyo, former ROK presidential candidate and now leader of the opposition Liberty Korea Party, urged the United States, South Korea and Japan to form a “freedom nuclear alliance” and to base nuclear weapons in all three countries to counter the growing North Korea nuclear threat. He also warned that if the United States turned a deaf ear to his appeal, South Korea and Japan should seek to join the ranks of nuclear powers to create a “nuclear balance of power” with the North. That said, the opposition has been out of power for less than a year and these hawkish views are no doubt politically opportunistic. Moreover, it is not axiomatic that the conservative party, should it regain power, would act on these convictions, given the serious costs it would confront if it decided to acquire nuclear weapons.

The US and South Korean governments have maintained a longstanding dialogue over extended deterrence and reassurance. But it is unclear whether any of the measures the US has proposed or taken, such as lifting restrictions on the South’s ballistic missile capabilities, have assured the South Koreans about the credibility of America’s nuclear umbrella. The administration has talked about deploying additional “strategic assets” to South Korea and the US Navy currently has three aircraft carrier battle groups operating in the western Pacific, although it has been vague about the specifics.

Until recently, South Korean fears of US nuclear abandonment and the proposals they spawned for the re-deployment of US TNW were largely confined to the extreme right wing of the Korean opposition. This is no longer the case, mainly because of North Korea’s rapid progress toward an operational ICBM capability and growing doubts about the US commitment to South Korea arising from President Trump’s antagonistic behavior toward key alliance issues. According to recent polls, 68 percent of the South Korean public currently supports the re-introduction of US nuclear weapons in South Korea and 60 percent want South Korea to acquire its own nuclear weapons.

These shifting attitudes should not be surprising based on the US experience in maintaining its extended nuclear deterrent in Europe during the Cold War. Just as the French questioned whether the United States would trade Paris for New York, South Koreans have worried in the past and worry more today about whether Washington would risk Seattle for Seoul. These concerns will no doubt be magnified by North Korea’s November 29 test of an ICBM with significantly improved capabilities to target the United States and the continued doubts of many experts about the ability of the US national missile defense systems to successfully intercept North Korean missiles.

In fact, in the 1970s, South Korea tried to clandestinely develop nuclear weapons to confront overwhelming North Korean conventional military superiority. And while it abandoned its efforts under US pressure, Seoul possesses the material, technology and expertise to quickly resume this effort. This type of reaction is not unique. Beginning in the 1950s, France started to lose confidence in America’s resolve to risk nuclear war with the Soviet Union to defend it against a nuclear attack, leading the French to field an independent nuclear deterrent several years later. Perhaps more tellingly, in the mid-1980s, America’s NATO allies insisted that only new ground-based deployments of intermediate-range nuclear weapons on NATO territory would counter Russia’s growing capabilities in these systems, despite American assurances that sea-based nuclear weapons were sufficient to maintain the link between the US nuclear deterrent and the defense of Europe. These lessons should not be lost on American policymakers when considering Seoul’s current strategic fears.

The Case For and Against Deploying TNW in South Korea

South Korean hawks have marshalled several arguments to defend their view that the US should deploy nuclear weapons on their territory and even allow the South to become a nuclear weapons state. According to this perspective, the North Koreans are unlikely to accept denuclearization unless they face considerably more pressure, and a more robust US and South Korean nuclear presence would provide badly needed leverage to force the North to bargain away its own nuclear capabilities. In addition, US TNW in South Korea or a nuclear-armed South Korea would counterbalance North Korean nuclear weapons and thus deter the North from starting a nuclear war or trying to use its unilateral nuclear advantage to coerce political concessions from the South. Moreover, confronting China with the prospect of a nuclear South Korea (and Japan) and an increased risk of nuclear escalation might be enough to scare China into using its leverage to force North Korea to give up its nuclear weapons.

Although these arguments have gained some traction among the South Korean public, there are compelling reasons for the US to refuse redeployment of TNW in South Korea and reject its development of nuclear weapons. First, the existing US nuclear umbrella, especially sea-based weapons that roam the waters of the Western Pacific, and the presence of US forces in South Korea provide ample deterrent to the use of North Korean nuclear weapons. If these capabilities do not deter the North from starting a war, basing a few more weapons on South Korean soil will not change this calculus.

A US decision to redeploy TNW would also raise the thorny issue of operational decision-making and command authority over the use of these weapons. The South Korean government, like the governments of NATO countries where nuclear weapons are based, might prefer command arrangements with shared authority (in NATO, parlance “dual key” arrangements exist that require positive actions by both the US and basing countries to order nuclear release.) However, the commander of US Forces Korea would almost certainly want sole authority to employ these weapons. And because of the compressed time for decision-making due to the short distances involved, he might be given pre-delegated launch authority in certain conditions. Under these circumstances, and especially because both US and North Korean nuclear weapons would be highly vulnerable to a pre-emptive first strike, there would be strong incentives on both sides to use these weapons first or risk losing them. Thus, the re-introduction of US TNW in South Korea, while aimed at deterring a North Korean nuclear attack, could actually increase the risk of a nuclear exchange.

Moreover, it is likely that North Korea would react to the deployment of nuclear weapons in South Korea by accelerating its own development and deployment of shorter-range nuclear weapons. This could trigger an arms race, with both sides locked in an action-reaction cycle, adding to their deployments but producing greater instability at a higher level. Although the US could draw on a stockpile of air-delivered nuclear gravity bombs in the United States, it would be difficult, expensive and time-consuming for the US to deploy these assets to South Korea and build the infrastructure to provide weapons security and maintenance, even if the ROK were prepared to defray some of these costs.

Lastly, a decision by the US to re-introduce TNW to South Korea would likely draw strong congressional opposition amid already growing concerns about the president’s unlimited authority to order nuclear strikes and the dangers of a nuclear war with North Korea.

Is There a Middle Ground?

Given Moon’s opposition and the substantial risks and costs of a South Korean decision to join the nuclear club, it is not a foregone conclusion, as former Secretary of State Henry Kissinger seemed to suggest in a recent interview, that a nuclear South Korea is inevitable, and that crossing this threshold would ignite a chain reaction of nuclear dominoes throughout the region. But at the same time, Moon’s position now reflects a minority view among the South Korean public—and whether he will be able to deflate pressure for a South Korean nuclear deterrent remains uncertain if the North Korean nuclear threat continues to grow unconstrained.

There is no military justification for developing or deploying nuclear weapons for use on the peninsula because US conventional and nuclear weapons can cover any targets that need to be destroyed in North Korea. Further, such improvements would invite potentially destabilizing reactions from North Korea and China, possibly even Russia, and legitimize North Korean nuclear weapons.

Against this backdrop, regular demonstrations of the strategic nuclear capabilities the US already has for possible employment in a conflict could help to address the political, perceptual and psychological factors driving many South Koreans to consider nuclear weapons. The following measures should be considered if it looks like Moon is waging a losing battle with South Korea’s nuclear hawks:

  1. Make more frequent ballistic missile submarine (SSBN) visits to South Korean ports and increase the tempo of their operations in the western Pacific; the goal should be to maintain a SSBN presence in the area at least 75 percent of the time if that can be done without compromising operational security;
  2. Conduct more frequent rotational deployments of US dual-capable aircraft to South Korean air bases so that these strategic assets are present on South Korean soil 75 percent of the year. These units would exercise regularly with South Korean forces;
  3. Publicly offer a USG commitment, if operationally feasible, to put a handful of dual-capable aircraft on a 72-hour “tether” to South Korea prior to the commencement of hostilities and exercise this capability regularly to demonstrate our capacity to implement this commitment. The US has made similar commitments to other US allies (e.g., Saudi Arabia during the first Gulf War) and during the Cold War regularly exercised its reinforcement plans for Germany; and
  4. Create a US-ROK nuclear consultative group, modeled after the Nuclear Planning Group in NATO, to discuss nuclear policy, planning, doctrine, operations and incidence management procedures as they relate to operational plans for the defense of South Korea in a WMD environment. Japan could eventually be invited to join this mechanism if South Korean-Japanese security cooperation improves.

These improvements should only be made, however, in conjunction with three major changes in US strategy in order to reduce the risk of North Korean miscalculation:

  • The administration should not engage in rhetoric implying a US commitment to regime change or that the US would use nuclear weapons against the North in response to further North Korean threats or provocations;
  • The president and all senior US government officials must make it publicly clear that the US would only attack North Korea in response to a North Korean attack on the United States or one of its allies; and
  • Washington should signal to Pyongyang that it is prepared to enter into bilateral negotiations without any preconditions.

The administration should also signal to the North that it is willing to roll back these measures in the context of progress toward its ultimate goal of a nuclear-free Korean peninsula. A dual-track strategy of visibly demonstrating existing US nuclear capabilities available for potential use against North Korea and gestures to advance dialogue and diplomacy offers the best prospects for defusing the threat of a nuclear South Korea without aggravating the risk of war with North Korea.


If left unaddressed, the growing existential angst of the South Korean public and political class over the rapidly growing North Korean nuclear and ballistic missile threat has the potential to cause serious strains in the US-ROK alliance and hasten the proliferation of nuclear weapons in the Asia Pacific. There’s an old adage that “you can’t beat something with nothing.” Unless the US takes more concrete and visible steps to demonstrate the continued viability of its nuclear umbrella than it has offered to date, the South Koreans may eventually decide to go their own nuclear way, with potentially disastrous consequences for peace and security in Northeast Asia and the future of the global nuclear nonproliferation regime.


Richard Sokolsky, currently a nonresident senior fellow at the Carnegie Endowment for International Peace, served in the State Department for 37 years, including seven as Director of the Office of Strategic Policy and Negotiations from 1990-1997. From 2005-2015 he was a member of the secretary of state’s Office of Policy Planning.

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