North Korea’s Tactical Nuclear Plans Are a Dangerous Proposition

A little more than four years ago, North Korean leader Kim Jong Un declared his country’s nuclear deterrent complete following the first test of a large intercontinental-range ballistic missile (ICBM) capable of reaching the entirety of the U.S. homeland. Since then, however, North Korea has continued to expand the size and sophistication of its nuclear forces.

One particularly worrying goal, announced last year by Kim, is the pursuit of tactical nuclear weapons. If developed and fielded, tactical nuclear weapons would lower the already-low threshold for nuclear weapons use on the Korean Peninsula. The implications for U.S. and South Korean security are severe. The Biden administration has stated its intent to “make practical progress that increases the security of the United States, our allies, and deployed forces.” Although efforts to dissuade Pyongyang from acquiring strategic weapons have failed, it’s now time to focus on the pending threat from North Korea’s tactical weapons.

North Korea’s introduction to tactical nuclear weapons would seriously complicate matters on the Korean Peninsula, potentially enable new forms of dangerous brinkmanship, and even instigate conventional adventurism against South Korea. Introducing tactical nuclear weapons into North Korea’s nuclear forces would create incentives to adopt more dangerous nuclear command and control practices, which could create new pathways to unintentional or inadvertent nuclear use. And while disarmament seems far off at best, tactical nuclear weapons would make an already nearly intractable problem even tougher.

In the face of a conventionally superior U.S.-South Korea alliance at its doorstep, North Korea has sought out nuclear weapons as an equalizer. Kim seeks, above all, to deter an offensive military campaign by the alliance to forcibly end his regime—a concern that strongly weighed on his father in the immediate aftermath of the 2003 U.S. invasion of Iraq. In North Korean thinking, early nuclear weapons use in a crisis against military targets—including airfields, ports, and other logistics nodes—would significantly complicate military operations for the alliance. By then using intercontinental-range systems and a handful of short- and medium-range delivery systems to threaten population centers in the United States, South Korea, and even Japan, Kim would hope to terminate a conflict on favorable terms by dissuading continued escalation out of fear of nuclear attacks on U.S., Korean, or Japanese soil. North Korea would hope that these systems held in reserve would dissuade continued escalation.

At the Eighth Congress of the Workers’ Party of Korea in January 2021, Kim outlined a wide-ranging set of military and nuclear modernization objectives aimed at fleshing out this strategy. In the months since, many of these objectives have been pursued; North Korea has tested hypersonic weapons, long-range cruise missiles, and an ICBM. According to a state media paraphrase of his remarks at the party congress, Kim said it was “necessary to develop tactical nuclear weapons,” which would be used for “various missions.” There’s no universal definition of what exactly constitutes a tactical nuclear weapon, but in general, these weapons feature a deliberately reduced nuclear explosive yield; shorter ranges; and, compared to strategic weapons, a lower perceived potential for escalation following their use. Beginning in February, North Korea began reconstituting its sole known nuclear test site at Punggye-ri. South Korean intelligence anticipates a return to nuclear testing—probably to realize Kim’s tactical nuclear weapons goal. In April, Kim oversaw the test of a new short-range missile that North Korean state media said was meant for “enhancing the efficiency in the operation of tactical nukes.” This was the first time a tested weapon system was explicitly framed as having a tactical nuclear weapons delivery role.

This press for new weapons comes in part because debates concerning the credibility of North Korea’s nuclear capabilities and strategy haven’t fully abated since the 2017 demonstrations of capability. Even after Kim’s three ICBM tests that year and one more this year, including a possible failed test, many continued to doubt whether a North Korean nuclear-armed warhead would survive atmospheric reentry and successfully detonate. This line of inquiry, however, ignored the fundamental North Korean interest in manipulating risk and manifesting, as the nuclear strategist Thomas Schelling warned, a “threat that leaves something to chance.” By demonstrating a baseline set of capabilities, Kim could seed enough doubt in the mind of a U.S. president that resorting to an attack might beget uncontrolled escalations that could end with a North Korean nuclear warhead detonating over an American city.

These North Korean developments have invited well-placed concern in South Korea and the United States that Pyongyang may explore the benefits of nuclear brinkmanship in future crises. In the face of North Korean conventional adventurism—of the sort South Korea experienced in 2010, for instance—the alliance could be paralyzed without credible retaliatory options should tactical nuclear weapons be fielded by North Korea.

Schelling described the nuclear brink not as “the sharp edge of a cliff” with a clearly observable point of no return but as a “curved slope that one can stand on with some risk of slipping.” North Korea’s introduction of tactical nuclear weapons would, in effect, manipulate this slope and, in the context of a limited conventional conflict, invite the United States and South Korea to stand on it. The already great nuclear dangers on the peninsula would be amplified, and deterrence of a nuclear-armed North Korea would grow more complicated yet.

In the 1950s, NATO faced a set of conundrums not so dissimilar to North Korea’s today: Fears of conventional inferiority vis-à-vis the Soviet Union in Europe motivated interest in the early use of nuclear weapons. The alliance sought to “ensure the ability to carry out an instant and devastating nuclear counteroffensive by all available means and develop the capability to absorb and survive the enemy’s onslaught.” One of the means to make this more credible—both to NATO allies and the Soviet Union—was to delegate the authority to release short-range nuclear weapons to military commanders. Although perspectives on nuclear use would change over time as a norm against nonuse ossified, then-U.S. President Dwight Eisenhower in 1955 said tactical nuclear weapons, in the context of “strictly military targets and for strictly military purposes,” could be used “just exactly as you would use a bullet or anything else.”

This logic was compelling in the context of the challenges that NATO faced at the time—and may be so today in a chronically insecure North Korea. Pyongyang’s lack of sophisticated intelligence, surveillance, and reconnaissance capabilities contribute to a general lack of strategic situational awareness. Meanwhile, the pursuit and deployment of advanced conventional precision strike systems in South Korea, including by fifth-generation stealth fighters, raise the prospect that Kim could be killed early in a crisis before having a chance to issue an order for the use of nuclear weapons. Although North Korea has so far indicated that, like in the United States, only Kim possesses the sole authority to authorize nuclear use, tactical nuclear weapons would create strong incentives—especially in a crisis, if not in peacetime—to pre-delegate authority to trusted field commanders to employ these weapons.

The lack of good warning and intelligence, combined with increased nuclear authority for lower-level commanders, would certainly manipulate Schelling’s “curved slope” to become ever steeper. Although this may manifest in enhanced deterrence for North Korea, it would create numerous pathways to inadvertent nuclear escalation. For instance, in the fog of war during what would otherwise be a limited, conventional conflict, a particularly paranoid North Korean field commander might misinterpret benign phenomena, such as a civilian airliner straying a little too close to North Korean airspace, as a U.S. strategic bomber and authorize nuclear use. Similarly, North Korea has implied that it would attack South Korean air bases that host low-observable F-35A stealth fighters. Because these aircraft would be practically invulnerable to North Korea’s obsolete air defense systems, the incentives to strike early in a conflict are significant.

Given North Korea’s existing preference for strongly assertive and centralized control over nuclear weapons, there’s a sliver of good news in that Kim may be unwilling to hand over control of the button—even for tactical weapons—in peacetime. But tactical nuclear weapons would also create strong incentives to disperse the storage of nuclear weapons. North Korea is thought to currently use a single warhead storage site; dispersed nuclear weapons at multiple North Korean military bases would raise the risk of inadvertent escalation. A U.S. or South Korean attack on such a base in a limited conventional war could be interpreted by North Korea as the initiation of a broader campaign to disarm Kim of his nuclear weapons.

The United States and South Korea broadly recognize the growing severity of the challenge posed by North Korea’s fast-advancing nuclear capabilities. At a December 2021 meeting of the U.S. defense secretary and his South Korean counterpart, the two sides acknowledged that the alliance needs to adapt to rapidly advancing North Korean capabilities. In the absence of any constraints on its programs, North Korea has continued to modernize and broaden its capabilities.

But the alliance—and policymakers in both Seoul and Washington—remain poorly positioned to contend with the approaching challenge of North Korean tactical nuclear weapons. Because overarching policy framing continues to be denuclearization, which treats the North Korean issue as a nonproliferation problem, threat reduction, confidence-building, and arms control are largely overlooked. A useful premise for policymakers to build on would be to recognize that the sources of insecurity that drive North Korea to seek tactical nuclear weapons can be addressed through a broader process of conventional and nuclear threat reduction. An example of the sort of initiative that could be usefully built on in this regard is the 2018 North and South Korean Comprehensive Military Agreement.

The Biden administration’s pledge to “make practical progress that increases [security]” on the Korean Peninsula is laudable, but it should be accompanied by new thinking on how to shape Kim’s choices about his evolving nuclear arsenal. Above all, even if constraints are not feasibly implemented before North Korea moves to deploy tactical nuclear weapons and other, new nuclear delivery systems, the United States should recognize that it is—like it or not—in a nuclear deterrence relationship with North Korea. Managing risk and avoiding nuclear conflict will require, at the least, initiating a dialogue with North Korea on these issues. The burdens of coexisting with and deterring a nuclear-armed North Korea are simply too great to leave these matters unaddressed.