This post is authored by Duyeon Kim, adjunct senior fellow at the Center for a New American Security and columnist with the Bulletin of the Atomic Scientists. It is part of a project conducted by the program on U.S.-Korea policy at the Council on Foreign Relations, supported by the Smith Richardson Foundation and Korea Foundation. This series of posts addresses the U.S. nuclear posture in Northeast Asia, implications of North Korean nuclear and missile programs for U.S. extended deterrence commitments, operational and tactical dimensions of deterrence on the peninsula, and regional dimensions of stability. To further stimulate an open discussion of these issues, we would like to invite reader responses. Please contact Ellen Swicord at email@example.com for submission guidelines if you are interested in contributing a response.
Each time the world witnesses cycles of North Korean provocations or nuclear diplomacy, or both, Korea watchers and specialists question whether deterrence is possible or feasible. The answer to this question has become more complex over the past several decades because the object of deterrence—the number of undesirable North Korean actions—has grown in tandem with Pyongyang’s growing military capabilities. The expanding scale, scope, and number of North Korean actions the United States and South Korea wish to deter has, in turn, naturally caused confusion in the international discourse, resulting in frequent use of the term “deterrence” without clarifying the target(s) of deterrence and by conflating the definitions of deterrence, compellence, and other foreign policy tools. Any answer to the fundamental question of whether deterrence is possible vis-à-vis North Korea depends on the target(s) of deterrence, which necessitates a clear definition of deterrence and clarification of the target behavior(s) for deterrence. Based on this clarification, the policy objective can then be defined, followed by an identification of the appropriate foreign policy tools to use to achieve the designated objective.
Deterrence is a strategy aimed at discouraging an adversary from taking an unwanted action (usually military in nature) by raising the cost of that action and instilling credible fear of the consequences. Nuclear deterrence discourages an adversary from using nuclear weapons for fear of retaliation. Once an adversary has already taken an unwanted action, however, deterrence has failed and the question becomes one of compellence—persuading or forcing an adversary to give up something it already possesses or to terminate an ongoing action(s)—or the use of other policy tools. Compellence is harder to execute than deterrence because it requires persuading an adversary to change its existing behavior (e.g., taking an action it otherwise would not take) and a credible commitment to act against the adversary by imposing costs (e.g., threat to inflict punishment) in the event the adversary refuses to comply, or actually executing a costly action (e.g., following through on the threat), both with a deadline. Deterrence, on the other hand, is not associated with a deadline to act against an adversary.
In the case of North Korea, one objective of deterrence was to discourage North Korea from acquiring nuclear weapons, but after Pyongyang crossed that threshold, the question turned into one of compellence: how to compel the regime to relinquish its nuclear weapons while simultaneously deterring it from using those weapons. However, due to the risks involved, to this day no American administration has considered the use of a compellence strategy. Potential risks of compellence include reputational consequences, undermined credibility, and military escalation. Opposition by Northeast Asian countries and North Korea’s ability to retaliate would also deter the United States from lodging compellent threats against Pyongyang. Though President Donald J. Trump’s “fire and fury” rhetoric in 2017 resembled compellent threats, they were largely viewed as bluster that lacked credibility and pandered to his domestic audience. Nevertheless, Trump’s rhetoric was dangerous because of the possibility that it could have spiraled into inadvertent conflict. Since the 1990s, the United States has used diplomacy, rather than compellance, as the preferred foreign policy tool to attempt to denuclearize North Korea.
From Deterrence to Complexity
The United States’ deterrence record is spotty vis-à-vis North Korea, and a judgement of its success or failure hinges on the definition of deterrence’s ultimate target behavior(s) or action(s). There have been some clear failures and the jury is still out on whether the United States’ two areas of success—preventing armed conflict and North Korea’s use of a nuclear weapon—will remain successes going forward. Meanwhile, the current summitry to denuclearize the regime could result in success, failure, modest progress, or maintenance of the status quo.
The target of U.S. deterrence has evolved and expanded over time with Pyongyang’s development of its military capabilities. After the 1950-1953 Korean War, the objective of deterrence was to discourage North Korea from invading the South again and from engaging in acts of terrorism. The main deterrent against North Korean aggression was (and remains) the U.S.-South Korea alliance, operationalized by the stationing of U.S. troops on and around the peninsula, maintenance of American nuclear weapons on South Korean territory until 1991, provision of the U.S. extended nuclear deterrent (or nuclear umbrella) over South Korea, and the conducting of combined defensive military exercises every year. These components constitute a deterrence strategy by providing the capability to impose costs in the event North Korea acts aggressively (e.g., invades or attacks the South), and they demonstrate America’s resolve and political will to act (e.g. threat of retaliation) in the event of North Korean aggression. Deterrence, however, has failed to prevent Pyongyang from engaging in numerous provocations (limited, calculated acts of aggression beyond nuclear and missile tests) and acts of terrorism over the past fifty years that have resulted in the deaths of American and South Korean civilians and soldiers.
In the early 1990s during the George H.W. Bush and Bill Clinton administrations, the objective of deterrence continued to lie in preventing another war, but with an additional target: deterring North Korea’s acquisition of a nuclear weapons capability. Deterrence continued to succeed in preventing another armed military invasion of the South, but failed to prevent North Korea’s acquisition of nuclear technology for military purposes. As such, the policy question was no longer one of deterrence because Pyongyang eventually obtained nuclear technology and capability. However, compellence was not a politically feasible or a credible course of action either. In 1993, President Bill Clinton lodged a deterrent threat, not a compellent threat: “We would overwhelmingly retaliate if [the North Koreans] were to ever use, to develop and use nuclear weapons. It would mean the end of their country as they know it." His administration even prepared military strike operations targeting the Yongbyon nuclear complex, but was deterred from executing them because of Seoul’s opposition (e.g., fear of escalating into another war) and former President Jimmy Carter’s trip to Pyongyang. The Clinton administration quickly pivoted to a focus on diplomatic negotiations to roll back North Korea’s nuclear weapons program.
In the early 2000s during the George W. Bush administration, the number of North Korean actions the United States sought to deter expanded because North Korean military capabilities and “bad behavior” increased. These targets included deterring Pyongyang from further advancing its nuclear weapons arsenal (through vertical proliferation, nuclear tests, and missile flight tests), to waging a range of provocations beyond nuclear and missile tests, and engaging in horizontal proliferation (the transfer of WMD parts and technology) and illicit activities. Deterrence has yet to succeed in these areas, and many Korea watchers would argue that it has already failed. Still, although U.S. policy through the Six Party Talks (2003–2008) failed to dismantle Pyongyang’s nuclear programs, deterrence continued to prevent a North Korean invasion and the use of a nuclear weapon during the Bush administration.
During the Barack Obama administration from 2009 to 2017, the targets of deterrence expanded even further due to reports that Pyongyang had the ability to miniaturize a nuclear warhead that could be mounted on a missile. The prevention of malicious cyber operations emerged as another target of deterrence. During this time, deterrence failed to prevent provocative acts such as North Korea’s shelling of South Korea’s Yeonpyeong Island and the sinking of the Cheonan corvette in 2010, while the United States dissuaded Seoul from retaliating due to concerns over potential escalation. Instead, in response to Pyongyang’s ongoing nuclear and missile testing, Washington and Seoul increased their deterrence capabilities by incorporating U.S. strategic assets (such as B-52 bombers flying over the Korean Peninsula) and including decapitation exercises in their combined military drills. These measures were intended to assure South Korea of the United States’ security commitment and to send a deterrence message to the North. But Pyongyang’s provocations and continued advancements in its nuclear weapons capability elicited increasing debate and anxiety in Seoul about Washington’s commitment to its extended deterrent and the effectiveness of the alliance’s deterrence posture and capabilities. Stronger deterrence posture and capabilities also stoked fears among some circles in Seoul and Washington that Pyongyang could misperceive measures intended to assure U.S. allies as offensive actions aimed at the North.
Deterrence, meanwhile, continued to succeed in preventing North Korea from using its nuclear weapons or attempting to invade the South during the Obama administration, but failed to discourage Pyongyang from conducting more nuclear and missile tests, enhancing its nuclear arsenal, and engaging in other asymmetric provocations such as cyberattacks on Sony and South Korean banks and government sites. U.S. diplomacy also failed to terminate Pyongyang’s nuclear weapons programs.
Deterrence Challenges During Summitry and Beyond
Today, the overall targets of deterrence continue to be preventing North Korea from starting another war, using nuclear weapons, and waging provocations outside the realm of nuclear tests and long-range ballistic missile launches. The aim of U.S. policy, meanwhile, remains to dismantle Pyongyang’s nuclear weapons capability through the ongoing, yet uncertain, summit process.
The United States should continue to use diplomatic negotiations as its main foreign policy tool to denuclearize North Korea while maintaining a robust deterrence posture. However, in this uncertain period of détente the United States and its allies face challenges in deterring North Korea from taking a wide range of undesirable actions. First, Trump has identified the testing of nuclear devices and long-range ballistic missiles as red lines, suggesting that his target of deterrence is the suspension of these tests only, without publicly articulating any costs he will impose if Pyongyang resumes testing. This perception provides Pyongyang with a free pass to wage other forms of provocations, such as the testing of short-range ballistic missiles in May, which threatens South Koreans and Americans living in the South and confounds U.S.-South Korea missile defenses. It also allows the regime to continue mass-producing and advancing nuclear weapons without restrictions or consequences.
Second, Trump’s unilateral cancellation of U.S.-South Korean combined military exercises, abruptly announced at the June 2018 Singapore summit, weakens the allies’ military readiness and inter-operability, which are critical for maintaining the capabilities that are the linchpin in the U.S.-South Korea deterrence posture. The move satisfied Pyongyang’s demands for an end to these drills, which it claims are rehearsals for war, but many Korea watchers worry that the cancellation of combined exercises weakens the allies’ readiness against North Korean aggression and is a stepping stone to eventually ridding U.S. troops from the peninsula and breaking the U.S.-South Korean alliance. While these large-scale drills were replaced with smaller-scale command post exercises and revised field training programs to provide space for diplomacy, they have not led to material changes to North Korea’s military posture or readiness, or incentivized Pyongyang to take meaningful denuclearization measures. General Robert Abrams, commander of the U.S.-South Korea Combined Forces Command, testified in February that North Korea’s military continued its winter training exercise with the same size, scope, and timing as previous years.
Third, progressive South Korean administrations are more reluctant than their conservative counterparts to take any measures that could aggravate the North. This makes it more difficult to respond, even proportionately, to North Korean provocations during periods of engagement. Pyongyang has further complicated matters with its exploitation of the gray zone between war and peace by engaging in aggressive and coercive actions that narrowly skirt the border between provocation of escalation and conflict. Most recently, North Korea launched two rounds of short-range solid-fuel ballistic missiles in May and reportedly waged cyberattacks on the United States, South Korea, and ally nations after Trump and Kim met in Singapore last June and during the February Hanoi summit this year. Proportionate reactions using diplomatic, economic, and information tools do not need to trigger escalation or sever dialogue channels. However, turning a blind eye to lower-level provocations only enables North Korea to continue these offenses and sends the wrong message that it can still seek considerable advantage, influence, and damage without crossing Trump’s red lines.
If the target of deterrence is to prevent another war and the use of a nuclear weapon, then the United States should maintain a robust deterrence posture and capabilities, which have so far proven to achieve this objective. But if the object of deterrence is to dissuade all bad behavior by North Korea—including but not limited to further nuclear and missile testing, a military attack or invasion of South Korea, disruptive cyber operations, illicit financial activities, acts of terrorism, production and use of chemical and biological weapons, and conventional military provocations short of war—then the United States should employ a comprehensive policy that incorporates a spectrum of tools spanning diplomacy, modern and tailored deterrence, and gray-zone tactics. As North Korea’s military arsenal expands and becomes more sophisticated with the incorporation of new technologies, America’s toolkit and policy must also evolve.