Goals for any arms control proposal with North Korea

President Donald J. Trump and North Korean leader Kim Jong-un are expected to meet for a second summit in Hanoi, Vietnam, at the end of this month, with the goal of building on the largely symbolic outcomes of their first meeting in Singapore in June 2018.

Assuming the summit goes forward, what should the United States and its allies aim for when it comes to pursuing negotiations that limit North Korea’s nuclear weapons capabilities—and what concessions should we consider giving in turn? What are the parameters of a plausible agreement that would serve US and allied interests?

These are tough questions, and may seem near-impossible to resolve at first glance.

But the mere fact that there have been negotiations between Kim Jong-un, South Korean President Moon Jae-in, and President Trump has relieved the pressures that were building toward a potentially deadly U.S.-North Korea military confrontation in the final months of 2017. Escalating bluster has given way to an ongoing diplomatic process, facilitated by a freeze of North Korean nuclear and missile tests, the suspension of major US-South Korean military exercises, and other measures intended to build confidence.

The present thaw, however, may not serve the interests of the United States and its allies if the two sides are unable to turn reciprocal tension-reduction gestures into durable agreements.

On the one hand, there is a real risk that failed diplomacy will lead to renewed confrontation. If the United States insists, as many senior officials have, on a maximalist outcome—“the final, fully verified denuclearization of North Korea”—it is all but guaranteed to be disappointed. While an admirable long-term goal, unilateral North Korean disarmament is an unrealistic short-term demand; nothing in North Korean behavior during diplomatic negotiations nor the body of historical evidence suggests that Kim is willing to give up his nuclear-weapons capability anytime soon. Indeed, a senior North Korean official explicitly stated that Pyongyang is not interested in diplomacy if the US goal is to force “unilateral nuclear abandonment” on North Korea’s part. If substantial progress toward unilateral disarmament is the standard for progress, both the United States (citing the growing North Korean nuclear threat) and North Korea (citing the lack of sanctions relief) are likely to grow impatient and return to browbeating.

Equally perilous is a second path, in which the leaders of the United States and South Korea care for and oversee the mirage of North Korean denuclearization, agreeing to steadily increase the normalization of relations with North Korea without putting in place any real limits on North Korea’s nuclear weapons capabilities. During the ongoing diplomatic process, North Korea’s nuclear weapons complex has continued operations and its production of nuclear delivery vehicles and fissile material has continued apace. North Korea is already a de facto nuclear-armed power, capable of threatening regional and probably most US homeland targets. Short of an immensely costly military campaign to disarm North Korea or an internal calamity in the North, the Kim regime will remain in power and continue to expand the size and improve the sophistication of its nuclear arsenal. Left unchecked, North Korea will pose an increasingly significant threat to the United States, South Korea, Japan, and the entire nuclear nonproliferation regime.

Instead, the United States and its allies should choose a third path: an approach that aims to quantitatively and qualitatively limit, rather than eliminate, North Korea’s nuclear weapons capabilities while maintaining a long-term goal of working toward North Korean disarmament. Agreements designed to limit North Korea’s nuclear weapons capabilities will be difficult to negotiate, but if properly conceived and carefully executed, they will serve US and allied interests by favorably managing competition with North Korea.

North Korea’s nuclear posture and strategy. In 2017, North Korea successfully flight-tested two separate ballistic missile designs capable of delivering nuclear payloads to the contiguous United States. Following the test of the Hwasong-15, a large intercontinental ballistic missile (ICBM) that appears to put most of the United States within its range, North Korean leader Kim Jong-un underlined that the “historic cause of completing the state nuclear force” had been realized, seemingly implying that he was now at a point where he could stop testing his nuclear and missile capabilities, at least for the time being. As Kim noted in his New Year’s Day 2018 address, it was time for North Korea to shift to the mass production of nuclear weapons capabilities. Although the region has recently been spared dramatic tests, North Korea continues to gradually build out a more formidable nuclear force during negotiations.

While Kim clearly values his nuclear weapons capability, calling it a “treasured sword,” there is uncertainty about the precise role that nuclear forces play in Pyongyang’s strategy, today and in the future. Pyongyang has not released an authoritative document—nor has its leadership made any statement—outlining force structure plans or doctrine. In this light, analysts are left to assess North Korea’s intent and capabilities based on imperfect available evidence. Insofar as nuclear doctrine is concerned, one helpful indicator is the country’s 2013 law “consolidating the position of nuclear weapons.” This law, among other things, clarifies aspects of nuclear command and control, codifies a negative security assurance for nonnuclear states, and sets out goals on nuclear security. The revision of North Korea’s constitution, a panoply of additional statements in North Korean state media, and speeches by prominent members of the regime flesh out a more complete picture.

The evidence suggests that North Korea will likely make its nuclear forces a large part of any effort to deter and, if necessary, defeat a US-South Korea invasion. North Korea has explicitly threatened to conduct theater nuclear strikes to prevent the United States from marshalling the forces required to conquer North Korea, and Pyongyang has conducted exercises simulating strikes on the port of Busan in South Korea and US military bases in Japan. North Korea’s ICBMs—in theory and when Kim is confident in their survivability—would be held in reserve to coerce US accommodation.

There are two plausible explanations for why North Korea would pursue this type of nuclear first-use strategy. Optimists argue that North Korea fears US-led regime change and seeks nuclear weapons to deter invasion. They see North Korea’s grand strategy as defensive and status-quo oriented. Pessimists, on the other hand, argue that North Korea sees nuclear weapons as both invasion insurance and an enabler of military aggression against South Korea and Japan—using nuclear weapons as a shield for aggression, the way Pakistan is believed to do. They see North Korea as revisionist and opportunistic. If North Korea believes that it can deter the United States and South Korea from pursuing regime change in a conflict, then it may think it can pursue limited violent aggression against South Korea and Japan with impunity—especially if it doubts the willingness of the United States to take on significant risk to defend its allies.

The case for agreements to limit North Korea’s nuclear weapons capability. For the United States, South Korea, and Japan, the goal should be to prove the optimists right—even if only in retrospect—by encouraging North Korea to accept a nuclear force posture consistent with a narrow, defensive view of the utility of nuclear weapons. As North Korea’s nuclear capability increases in size and sophistication, the Kim regime will gain greater confidence that it can successfully execute nuclear strikes in a conflict with the United States while living to fight another day. As a result, North Korea may be tempted to initiate provocations, escalate crises, or even risk war, thinking that its nuclear capabilities would allow it to favorably manage an escalating conventional conflict if necessary.

There are a number of ways that the United States can encourage North Korean restraint. The United States and South Korea have successfully deterred North Korea in the decades since the end of the Korean War. Despite multiple near-misses and intermittent violent provocations, the Korean Peninsula has not seen a large-scale conflict since 1953, due largely to the formidable military capability of the US-South Korea alliance. Going forward, Washington and Seoul should sustain this success by adapting their combined deterrence strategy to the changed situation. Sanctions, export controls, and counter-proliferation activities can help limit the growth of North Korea’s nuclear and conventional military capabilities. Investments in updated US, South Korean, and Japanese military capabilities can challenge North Korea’s confidence that it can carry out violent aggression and successfully execute nuclear coercion. Confidence-building measures can reduce tension and limit conflict flashpoints. And last but not least, formal and informal agreements can limit North Korea’s nuclear arsenal.

Even after the United States and its allies accept the reality of a nuclear-armed North Korea and shift their policy from insisting on unilateral disarmament to managing deterrence, they will nonetheless be interested in limiting North Korea’s nuclear weapons capabilities. North Korea, like all nuclear powers, has to manage resource constraints as it builds out a nuclear force—and its constraints are particularly acute. While we can assume Pyongyang has a minimal requirement for what is necessary to deter, the question is how much further North Korea might look to go and how the United States and its allies can limit its arsenal. Given limited resources and Kim’s stated desire to channel greater resources toward the rejuvenation of North Korea’s economy in the form of a “new strategic line,” Pyongyang may consider limits on the expansion of its nuclear weapons capabilities in exchange for specific US and allied concessions.

Any nuclear agreement that the United States and its allies reach with North Korea should contribute to four US goals: deterring North Korea from using nuclear weapons during a conflict; deterring North Korea from initiating violent nonnuclear aggression against South Korea and Japan; reducing the consequences of a conventional or nuclear war should deterrence fail; and limiting North Korea’s ability and willingness to transfer nuclear weapons-related capabilities and know-how to third parties.

To achieve the first three goals, the United States and its allies should attempt to limit the size and sophistication of North Korean nuclear forces. To achieve the fourth, we should limit North Korea’s available supply of material that can be used to produce nuclear weapons, and make any concessions to the Kim regime conditional upon the North withholding from any nuclear weapons-related proliferation activities—particularly the transfer of any nuclear materials to third parties.

In shaping North Korea’s nuclear posture, the United States and its allies cannot reasonably expect to completely negate the North Korean nuclear threat. Instead, they should seek an equilibrium where North Korea has enough nuclear capability that it is confident that it can deter preventive war, but not so much that it is confident that it can initiate conventional aggression and use nuclear coercion to control escalation. Broadly speaking, North Korea’s nuclear program exists within this equilibrium today, which is why a cap would be in US and allied interests.

Restraining North Korea’s nuclear weapons capabilities would make an important contribution to deterrence, by increasing likely US and allied resolve in the face of North Korean aggression. While North Korea’s ability to threaten to destroy a few US cities—even with uncertain probability of success—is probably enough to deter the United States from initiating an unprovoked war to disarm North Korea or dislodge the Kim regime, it would likely not be sufficient to deter the United States from intervening to stop North Korea from invading South Korea or punishing North Korea conventionally if it engaged in non-nuclear aggression in the region. If North Korea initiated a conflict, the United States would have a greater stake and, therefore, would likely be willing to risk a small North Korean nuclear attack. If, however, North Korea could reliably threaten tens or even scores of US cities, then the potential costs of US intervention would be far higher, potentially changing the US calculus. If North Korea perceives that the United States would be unwilling to take such a risk on behalf of an ally, it may be tempted to carry out violent military aggression. Independent of the United States, South Korea—and, in particular, Japan—are also likely to be more willing to stand against North Korean aggression if the nuclear threat against their territory remains limited.

Plausible limitations on North Korea’s nuclear weapons capabilities. The United States and its allies should consider what mechanisms of restraint would effectively limit North Korea’s nuclear arsenal and what concessions each category of limitation would be worth. As usual, the devil would be in the details: Whether an agreement serves US and allied interests would depend on the scope and rigidity of the limitation on North Korea’s nuclear forces, and the costs of the concessions required to secure the deal. There are three main avenues to pursue: limit North Korea’s nuclear weapons production and supply; limit the number of nuclear-armed delivery systems; and limit the development and production of nuclear-capable missiles and launchers.

Let us examine each of these approaches in turn:

Limit nuclear weapons production and supply .Limiting North Korea’s production of weapons-grade plutonium, highly enriched uranium, and tritium would limit its capacity to produce nuclear weapons. This would help to restrict the size and sophistication of North Korea’s deployed nuclear arsenal and also make it less likely that North Korea would transfer “special nuclear material”—plutonium, uranium 233, or uranium enriched in the isotopes uranium 233 or uranium 235—to third parties. Past agreements to limit North Korea’s nuclear production infrastructure, including the 1994 Agreed Framework and the 2012 Leap Day Deal, offer both a blueprint for what an agreement might look like and a cautionary tale regarding the difficulty of verification and sustainable implementation. North Korea’s history of violating agreements and hiding facilities would raise the level of verification required for the United States and its allies to accept an agreement. Moreover, it may be in US and allied interests to pursue an imbalanced agreement that focuses on limiting certain nuclear materials over others. An agreement that focuses on restricting plutonium and tritium production, for example, would limit North Korea’s production and deployment of more advanced nuclear weapons designs, restricting Pyongyang to more rudimentary bomb designs of the kind seen mocked up in front of Kim Jong-un in photographs released in March 2016.

Limit the number of nuclear-armed delivery systems. Limiting the overall level of North Korea’s nuclear force would reduce the nuclear threat to the United States and its allies. The history of US-Soviet and US-Russian arms control provides numerous examples of the types of limitations and verification agreements that could be applied to North Korea’s nuclear arsenal. But in the North Korean case, the United States would not submit to reciprocal limitations on its own nuclear forces. Negotiating an asymmetric yet equitable agreement would be more difficult, but not impossible. Particularly as an initial step, the United States and its allies might focus on limiting the deployment of particular weapons systems, like North Korea ICBMs and Hwasong-12 intermediate-range ballistic missiles. A more narrow limitation might be more tolerable to North Korea, while also requiring fewer US and allied concessions. From the US perspective, an agreement focused on ICBMs would likely be very attractive because it would reduce or eliminate the direct nuclear threat to the contiguous United States. Allies might support such an agreement if they thought it increased the credibility of US extended deterrence commitments but, depending on the specifics, may object to leaving North Korea with a robust regional nuclear strike capability.

Limit the development and production of nuclear-capable missiles and launchers. North Korea’s existing regional missile force is robust, but constraints on further advancement and deployment of missiles should not be overlooked. Solid-fuel missiles, like the land- and submarine-launched Pukguksong series, should merit special consideration, given the survivability advantages they confer over liquid-fueled systems, like the Hwasong-12, Musudan, Nodong, and extended-range SCUD. Where possible, the United States should seek to freeze further testing and development of more advanced North Korean missiles of all ranges. In addition, even if the United States is unable to win a commitment from North Korea to dismantle its ICBMs, it should work to freeze North Korea’s production of indigenously built ICBM transporter-erector launchers (TELs) for either the Hwasong-14 or the Hwasong-15. North Korea is thought to rely on an external supply of large TELs, but evidence of advanced industrial work on heavy vehicle design and manufacturing suggests that it may develop a domestic production capability for TELs or towed mobile erector-launchers. Alternatively, North Korea may explore alternate basing modes, including rail-mobile launchers. Given the dual-use nature of manufacturing technology, it is unlikely that North Korea will agree to a limitation on its industrial capacity. Pyongyang may, however, be willing to disavow or cap the deployment of certain launchers, which the United States could monitor with national technical means and targeted inspections.

Plausible US and allied concessions. Limitations on North Korean nuclear force development will not come cheap. For Kim Jong-un to accept an agreement, he would have to calculate that the benefits of the concessions provided are more valuable than the additional coercive leverage that would come from a larger, better-equipped nuclear weapons arsenal. Such concessions may be difficult for the United States and its allies to swallow, but would be worth it for the right agreement.

In negotiations, the United States and its allies should remain clear-headed and ensure that any agreement provides a net advantage to the United States, South Korea, and Japan compared to the present unconstrained situation. The United States and its allies should only limit their military activities or enable limited North Korean economic growth if they secure significant restrictions on North Korea’s nuclear forces, and thus a net improvement in US and allied security. US and allied concessions should also remain readily reversible in most cases, to ensure that North Korea clearly understands the cost of noncompliance. With those provisos in mind, the following are categories of concessions that the United States and its allies should consider.

US and allied security assurances. North Korea will be more likely to accept a reduced nuclear arsenal if it is less concerned that the United States and South Korea are pursuing what it has termed a “hostile policy” against the regime. To secure a nuclear deal with North Korea, the United States and South Korea would, at the very least, have to convince Kim Jong-un that they would not actively seek regime change if North Korea maintains only a small nuclear arsenal. In exchange for limitations, the United States and its allies should consider publicly and formally disavowing the pursuit of regime change by force, as long as North Korea meets certain conditions—to include not employing nuclear weapons. They should also be amenable to declaring the end of the Korean War and gradually reopening diplomatic relations. The presence of US diplomats and their dependents in Pyongyang would be an important assurance against a US preventative attack, and more regular dialogue would help prevent misperception of hostile intent on both sides. If negotiations proceed to significant limitations on North Korea’s nuclear arsenal, the United States and its allies should also consider negotiating a formal peace agreement. However, the United States and South Korea should make clear that they will only consider an agreement that supports the continuation of the US-South Korea alliance, including the presence of some US forces on the Korean peninsula.

Limitations on US and allied military posture and activities. To make their security assurances credible, the United States and South Korea will likely have to commit to adjustments in their military posture and activities on and around the Korean peninsula. The United States and its allies should not relinquish capabilities and exercises that are needed to maintain readiness and deter potential North Korean aggression, but should take steps to make clear that US and allied military posture and exercises are designed to be defensive. To that end, the United States should support efforts to reduce tension near the border, such as the recent agreements between Seoul and Pyongyang to establish buffer zones across the  Military Demarcation Line—popularly known as the Demilitarized Zone—on land, and the Northern Limit Line at sea. The United States and South Korea should also be open to modification or suspension of activities that North Korea interprets as provocative, such as certain US bomber missions and US-South Korea military exercises. Should the strategic situation evolve towards greater trust, officers of North Korea’s “Korean People’s Army” could be invited to observe non-sensitive allied exercises to confirm their defensive nature. If negotiations proceed to the point where North Korea has accepted significant, verifiable limitations on its nuclear arsenal, the United States and South Korea should also explore more ambitious conventional force limitations similar to those in the Treaty on Conventional Armed Forces in Europe, which, among other measures, apply quantitative and geographic limits on the deployment of specific types of military equipment. It is likely that conventional force limitations will occur in parallel to nuclear agreements, but there may be opportunities for cross-cutting deals that serve US and allied interests.

Limit sanctions and allow economic investment. Kim’s stated goal is to shift from investment in nuclear weapons to growing the North Korean economy. This opens up an opportunity to the outside world to exert influence: UN and US sanctions are a major barrier to North Korean economic development—making sanctions relief a key carrot to trade for nuclear capabilities limitations. Even if negotiations progress well, it would remain in US and allied interests to keep many sanctions and export controls in place, particularly those designed to limit the expansion of North Korea’s nuclear weapons program and other key military capabilities. Those concessions that the United States and its allies do agree to should be targeted—in other words, designed to hedge against possible North Korean cheating or a deterioration of South Korea-North Korea relations. And, where possible, these concessions should be structured to support the North Korean people, rather than the regime. Initial concessions should be small and easily reversible, such as the issuance of sanctions waivers for select investment projects. Only after the process develops and North Korea agrees to significant, difficult-to-reverse limitations on its nuclear program should concessions expand to allow more significant economic activity; the United States might, for example, support the repeal of certain sectoral sanctions. The existing UN Security Council sanctions resolutions will pose a challenge to this endeavor, but the United States should be open to a piecemeal reinterpretation and limited sanctions rollback in exchange for significant, verifiable limitations on North Korea’s nuclear forces.

The challenges of reaching a mutually acceptable agreement. Finding a mutually acceptable agreement with North Korea will be extremely challenging and, indeed, may prove impossible. But significant obstacles can, in theory, be overcome.

One challenge is finding the equilibrium where North Korea is satisfied with its ability to deter unprovoked invasion and the United States and its allies see North Korea’s nuclear posture as restrained and defensive. From a vastly inferior military position, Pyongyang may inherently mistrust any force limitation the United States is willing to tolerate, rendering the prospect of a mutually agreeable win impossible—particularly in the early stages of the process, when both sides would no doubt continue to harbor significant suspicions. But while a formidable obstacle, this situation may be solvable with a phased process of step-by-step concessions. In return for the right security and economic concessions, Pyongyang may view limitations on its nuclear weapons capabilities as worth the risk. Over time, successful agreements and continued diplomatic contact have the potential to reduce distrust and make more ambitious agreements possible.

Evolving US military capabilities—particularly conventional counterforce and missile defense—will present another challenge. US military development, procurement, and deployment may increase Kim’s belief in the vulnerability of his nuclear arsenal. To some extent, this is unavoidable because of the diversity of missions and scenarios driving US development efforts and the other significant US interests in the Asia-Pacific. The United States, therefore, should consider nuclear force limitation agreements that leave space for adjustments to North Korea’s nuclear posture if North Korea has reasonable concern about the survivability of its limited second strike capability. It should also be open to connecting limitations on certain US military deployments to verifiable limits on North Korea’s nuclear arsenal. Abandoning the US Ground-Based Midcourse Defense system would be politically infeasible and strategically imprudent, but the United States should consider caps on the deployment of ground-based interceptors in the right deal. As long as North Korea poses the most significant ICBM threat to the United States (outside of China and Russia, whose arsenals are not the measuring stick for US homeland defense) the sizing of the US Ground-Based Midcourse Defense system can and should be linked to the number and sophistication of North Korea’s deployed ICBMs.

An additional challenge is alliance coordination. An agreement will only support US interests if it avoids weakening the US-South Korea and US-Japan alliances. Allies are rightly concerned with North Korea’s nuclear development and, therefore, are likely to support verifiable limitations. But they may have different threat perceptions and priorities than the United States. Washington, for example, may be interested in beginning the process by pursuing a cap on North Korea’s ICBM arsenal. Seoul and Tokyo, by contrast, may not be comfortable with an interim deal that leaves North Korea’s theater-range nuclear-capable systems unchecked. In addition, Seoul and Tokyo are also likely to have different threat perceptions and negotiating priorities, requiring Washington to balance and coordinate between the two. These are not insurmountable obstacles, but will require sustained and serious consultations between the United States and each ally.

A final—and most critical—obstacle is verification and compliance. After decades of failed agreements and covert North Korean development, the United States will insist on agreements that can be clearly verified and have significant costs for noncompliance. North Korea, on the other hand, will be suspicious of US motives and no doubt voice strong opposition to any intrusive on-site inspections—especially of sensitive military sites and missile operating bases. One solution could be to involve the International Atomic Energy Agency (IAEA); a multilateral body—especially one with extensive prior experience in North Korea and an on-ground presence as recent as a decade ago—may be more acceptable to Pyongyang, and its conclusions about compliance would likely have greater international legitimacy. With or without the IAEA, overcoming mutual distrust will be an ongoing process, requiring progressively more ambitious limitations on North Korea’s nuclear forces connected to progressively more significant US and allied concessions. Initial limited agreements should be verified primarily by US national technical means, including satellite imagery, radar and sensor networks, and human intelligence, and connected to concessions that are limited in scope and can be easily revoked should North Korea fail to uphold its end of the bargain. If those agreements are successful, Pyongyang and Washington will be able to pursue broader agreements that require more significant on-site inspections and more permanent US and allied concessions.

The outlook for the future. Difficult as it may be, the United States and its allies must deal with North Korea as it is, not how we want it to be. In an ideal world, the Korean people would be re-united under a democratic government that protects the freedom and prosperity of its citizens. But the reality is a Korean peninsula that is divided, with the North ruled by a brutal regime that has a dreadful human rights record and has directly violated countless international obligations in its quest to develop nuclear weapons.

With no realistic prospect for immediate North Korean disarmament or a fall of the Kim regime, the United States should—with appropriate sobriety—shift to a strategy that aims to manage North Korea through a combination of deterrence, pressure, and targeted engagement. The United States should continue to pressure the Kim regime to meet its obligations to the North Korean people and the international community, and attempt to set the conditions for eventual disarmament and transformation of North Korea. But it should also pursue agreements designed to restrict North Korea’s nuclear weapons capability and thus reduce North Korea’s willingness to run nuclear risk in a crisis or conflict.

Finding a mutually acceptable agreement may not be possible overnight, but there is a plausible path by which sustained diplomacy and confidence-building can chip away at decades of mistrust and hostility. Moreover, even if US pursuit of an agreement ultimately fails, it will still have been worth the effort. If the United States makes a good-faith attempt to find durable solutions and faces unreasonable North Korean opposition, Kim Jong-un will have revealed the hostile intent behind his nuclear strategy. As a result, the United States will be in a better position to lead a coalition of allies and partners to deter and contain North Korea.

(Editor’s note: This article was written under the auspices of the FAS International Study Group on North Korea Policy. The views expressed are the authors’ alone.)