North Korean Nuclear Capabilities and U.S. Foreign Policy

Mark S. Bell

Over the course of 2017, North Korea’s nuclear program made giant leaps forward. While North Korea first tested nuclear weapons in 2006, the nuclear tests it conducted during its first decade as a nuclear power were unimpressive: its first four nuclear tests failed to achieve a yield larger than 15 kilotons, substantially smaller than the 25 kiloton yield the United States achieved in 1945 with the plutonium device dropped on Nagasaki. North Korea’s achievements in 2017, however, should leave little doubt that North Korea is now a full member of the nuclear club. A nuclear test in September 2017 with a yield of around 150 kilotons demonstrated that North Korea has mastered the ability to produce sophisticated, high yield nuclear weapons (either a two-stage thermonuclear weapon or a boosted fission weapon). Its missile tests during 2017 were equally impressive, showcasing the ability to launch a genuinely intercontinental capability that could reach any major American city.

North Korea, in short, now has the capability to hold the cities of the United States (and its allies in Asia) at risk with powerful nuclear weapons. Policymakers in the United States must reckon with these capabilities and get used to the constraints they impose on U.S. foreign policy. As much as American policymakers might want to wish away North Korea’s capabilities, or to play down North Korean capabilities, it is better to adjust the sails than to hope the wind disappears.

Today, North Korea benefits from nuclear weapons and this necessarily imposes constraints on U.S. foreign policy in the region. It is often said that nuclear weapons offer little beyond the ability to deter. In fact, precisely because they deter attack, nuclear weapons also act as a shield that reduces the risks and costs of pursuing a host of other foreign policy behaviors. Nuclear weapons can facilitate a range of objectives that states of all stripes may find attractive. Possessing nuclear weapons can allow states to act more independently of allies, engage in aggression, expand their position and influence, reinforce and strengthen alliances, or stand more firmly in defense of the status quo. States with nuclear weapons are aware of these benefits and use nuclear weapons to pursue them. This applies as much to democratic states committed to the status quo as it does to authoritarian or revisionist states.

Consider the case of Britain. A declining, status quo state when it acquired nuclear weapons in the 1950s, Britain was increasingly dependent on the United States for its security, facing growing challenges to its role as the preeminent power in the Middle East, while its commitments to allies were becoming increasingly uncredible. What did it do when it acquired nuclear weapons? Britain used nuclear commitments instead of conventional military commitments (which it could no longer afford) to reassure allies that were increasingly skeptical of Britain’s ability to come to their aid. Similarly, Britain’s nuclear weapons reduced the risks of acting more independently of the United States and of using military force to resist challenges to its position in the Middle East.

Or consider America’s own experience with nuclear weapons. In the aftermath of World War II, a newly nuclear United States put in place a globe-spanning network of alliances and military bases and embraced a forward-leaning posture wholly at odds with its prior history of avoiding entangling alliances and staying out of European conflicts. In the words of Secretary of State Dean Acheson, this amounted to a “revolution” in U.S. foreign policy. And it occurred while the United States simultaneously demobilized its armed forces in the aftermath of World War II. Nuclear weapons allowed the United States to resolve the contradiction between expanding its commitments and reducing its ability to meet those commitments through conventional military means. With its nuclear arsenal, the United States could maintain (and take on) alliance commitments around the world without deploying the conventional military forces that would previously have been needed to make such commitments credible. Similarly, holding a nuclear monopoly allowed the United States to engage in more active and belligerent diplomacy in response to perceived Soviet aggression and misbehavior, despite the Soviet conventional military advantage in Europe. In the words of a 1948 National Security Council report: “[I]f Western Europe is to enjoy any feeling of security at the present time…it is in large degree because the atomic bomb, under American trusteeship, offers the present major counterbalance to the ever-present threat of the Soviet military power.”

Today, North Korea is taking advantage of its nuclear weapons, just as past nuclear states have done. North Korea faces serious military threats from South Korea and the United States. South Korea is vastly more economically powerful and has the support of the most powerful state the world has ever known. Since the end of the Cold War, the United States—unconstrained by the absence of another superpower—has shown a repeated inclination to pursue regime change around the world, labelled North Korea as part of the “Axis of Evil,” imposed punishing sanctions on North Korea, and kept tens of thousands of forces stationed in the region. What are the political priorities for countries that face these sorts of threats? States in this position would generally like to weaken their adversaries’ alliances, resist their coercion and encroachment, keep them as far from core territory as possible, retain the ability to threaten them, and be able to tolerate higher levels of escalation in crises. While states in a more benign environment face fewer constraints and so can pursue a wider range of goals, states facing serious threats must seek to improve their position against the threat. Nuclear weapons help them do so.

More specifically, North Korea would like to be able to stop the United States from flying military aircraft close to its territory (particularly the B-1B Lancer flights from Guam) and weaken the U.S.-South Korean alliance. It would like to show that Washington’s threats of regime change or military intervention on the Korean peninsula are empty talk, and demonstrate that the United States is unable to shoot down its missiles. And North Korea may want to be able to more credibly threaten military action against South Korea. All of these make good strategic sense for North Korea as it seeks to reduce the threats it faces and strengthen its position on the Korean peninsula in the face of massive American and South Korean conventional military superiority.

How do North Korean nuclear weapons help it achieve these goals? By raising the dangers of escalation, North Korea seeks to drive wedges between the United States and South Korea and raise fears of alliance “decoupling,” as well as to make it riskier for the United States to fly planes close to its airspace or engage militarily on the Korean peninsula. North Korea launches missiles, daring the United States to try (and quite likely fail) to shoot them down; it refuses to back down when challenged; and it raises the possibility of more provocative nuclear tests, such as an atmospheric nuclear test over the Pacific Ocean.

These actions are predictable, because they advance North Korean national interests. But they are also dangerous, raising the risk of escalation. This is a feature, not a bug, of North Korean strategy. Raising escalation risks is exactly how North Korea hopes to convince the United States to back off and, therefore, to improve its position on the Korean peninsula. And in the process of such escalation, North Korea might be entirely rational to use nuclear weapons first if things got bad enough: threatening the limited first use of nuclear weapons is a tried and tested strategy that allows states that are outmatched in conventional military power to deter stronger states. Pakistan uses this strategy today to deter Indian attacks, and the United States used it during the Cold War in its efforts to deter the Red Army from invading Western Europe. This risk is exacerbated by the particular way in which the United States fights conventional wars. Any U.S. military operation against North Korea would likely begin with attacks against North Korean Command and Control systems that would threaten North Korea’s ability to use its nuclear weapons and raising the imperative for North Korea to “use them or lose them.”

Any serious policy demands a dose of reality. Denuclearization and regime change are no longer achievable without risking tens (and potentially hundreds) of thousands of American lives. North Korea has nuclear weapons, benefits from having them, and has no interest in giving them up. Denying this reality is not only delusional, but in fact encourages North Korea to take more belligerent actions, accelerate its nuclear program further, demonstrate its capabilities more clearly, and further exacerbate the spiral of escalation.

A better approach would be to seek limited concessions from North Korea in exchange for limited concessions by the United States. For example, North Korea might agree to eschew missile tests over the territory of South Korea and Japan, if the United States limited flights of B1-B bombers close to North Korean territory. Such a deal would acknowledge that North Korea’s capabilities impose constraints on U.S. foreign policy and grant North Korea benefits. At the same time, it reduces the risks of miscalculations or accidental escalation, diminishing North Korean fears of a surprise attack by the United States that could trigger incentives for North Korea to use nuclear weapons, and lending some stability to U.S.-North Korean relations. And if North Korea violated the deal, the U.S. could easily resume those flights.

North Korean nuclear weapons constrain the United States and its foreign policy in the region. But this does not mean the United States has to acquiesce to every North Korean provocation. Nuclear weapons might be useful, but they do not grant states free rein in international politics. During the Cold War, the United States accepted that it was not feasible to persuade the Soviet Union to give up its nuclear weapons, but this did not mean accepting every Soviet act that went against U.S. interests. Rather, it constrained what the United States could achieve because it had to recognize the reality of Soviet nuclear weapons and the benefits they provided to the Soviet Union. Today, denuclearization of the Korean peninsula is not a plausible goal, but the United States can nonetheless likely deter North Korea from taking the actions it worries most about, including an invasion of South Korea.

There are no free lunches in international politics. If the United States wants North Korea to constrain its nuclear program, it will need to offer North Korea something in exchange. And if the United States tries to pursue regime change or denuclearize North Korea by force, it must accept that North Korean nuclear capabilities allow it to force the United States to pay a high price for doing so.

Mark S. Bell is an Assistant Professor of Political Science at the University of Minnesota. His research focuses on nuclear weapons and proliferation, international relations theory, and U.S. and British foreign policy. His writings and research are available at

1 This draws on “North Korea Benefits from Nuclear Weapons. Get Used to It,” War on the Rocks, October 2, 2017, available at: For the research underpinning these arguments, see Mark S. Bell, “Beyond Emboldenment: How Acquiring Nuclear Weapons Can Affect Foreign Policy,” International Security, vol. 40, no. 1 (Summer 2015): 87-119; Mark S. Bell, “Nuclear Opportunism: A Theory of How States Use Nuclear Weapons in International Politics,” Journal of Strategic Studies, 2017.

These contributions have not been peer-refereed. They represent solely the view(s) of the author(s) and not necessarily the view of APS.