As North Korean dictator Kim Jong Un issues increasingly over-the-top threats—including intimations that he might launch nuclear strikes against the United States—officials in Washington have sought to reassure the public and U.S. allies. North Korea, they say, may initiate cyberattacks or other limited provocations, but the leaders in Pyongyang wish to survive, so they are highly unlikely to do anything as foolhardy as using nuclear weapons.

Despite those assurances, however, the risk of nuclear war with North Korea is far from remote. Although Pyongyang’s tired threats are probably bluster, the current crisis has substantially increased the risk of a conventional conflict—and any conventional war with North Korea is likely to go nuclear. Washington should continue its efforts to prevent war on the Korean Peninsula. But equally important, it must rapidly take steps—including re-evaluating U.S. war plans—to dampen the risks of nuclear escalation if conventional war erupts.

Ironically, the risk of North Korean nuclear war stems not from weakness on the part of the United States and South Korea but from their strength. If war erupted, the North Korean army, short on training and armed with decrepit equipment, would prove no match for the U.S.–South Korean Combined Forces Command. Make no mistake, Seoul would suffer some damage, but a conventional war would be a rout, and CFC forces would quickly cross the border and head north.

At that point, North Korea’s inner circle would face a grave decision: how to avoid the terrible fates of such defeated leaders as Saddam Hussein and Muammar al-Qaddafi. Kim, his family,—and his cronies—could try to escape to China and plead for a comfortable, lifelong sanctuary there an increasingly dim prospect given Beijing’s growing frustration with Kim’s regime. Pyongyang’s only other option would be to try to force a cease-fire by playing its only trump card: nuclear escalation.

It’s impossible to know how exactly Kim might employ his nuclear arsenal to stop the CFC from marching to Pyongyang. But the effectiveness of his strategy would not depend on what North Korea initially destroyed, such as a South Korean port or a U.S. airbase in Japan. The key to coercion is the hostage that is still alive: half a dozen South Korean or Japanese cities, which Kim could threaten to attack unless the CFC accepted a cease-fire.

This strategy, planning to use nuclear escalation to stalemate a militarily superior foe, is not far-fetched. In fact, it was NATO’s strategy for most of the Cold War. Back then, when the alliance felt outgunned by the massive conventional forces of the Warsaw Pact, NATO planned to use nuclear weapons coercively to thwart a major conventional attack. Today, both Pakistan and Russia rely on that same strategy to deal with the overwhelming conventional threats that they face. Experts too easily dismiss the notion that North Korea’s rulers might deliberately escalate a conventional conflict, but if their choice is between escalation and a noose, it is unclear why they would be less ruthless than those who once devised plans to defend NATO.

Even if the United States and South Korea anticipated the danger of marching to Pyongyang and adopted limited objectives in a war, nuclear escalation would still be likely. That’s because the style of conventional war that the United States has mastered over the past two decades is highly escalatory.

The core of U.S. conventional military strategy, refined during recent wars, is to incapacitate the enemy by disabling its central nervous system—its ability to understand what is happening on the battlefield, make decisions, and control its forces. Against Serbia, Libya, and Iraq (twice), the key targets in the first days of conflict were not enemy tanks, ships, or planes but leadership bunkers, military command sites, and means of communication. This new American way of war has been enormously effective. But if directed against a nuclear-armed opponent, it would pressure the enemy to escalate a conflict.

Preventing escalation in the midst of a war would require convincing North Korea’s leaders that they would survive, and so attacks designed to isolate and blind the regime would be counterproductive. Once airstrikes began pummeling leadership bunkers and severing communication links, the Kim regime would have no way of discerning how minimalist or maximalist the CFC’s objectives were. It would face powerful incentives to make the CFC attacks stop immediately—a job for which nuclear weapons are well suited.

The sliver of good news is that North Korea may not yet have the capabilities to carry out this strategy. It may not be able to tip its ballistic missiles with a nuclear payload, and its other means of delivering nuclear weapons remain limited. Given the rate of progress, however, if the regime does not have these capabilities today, it will soon.

What can be done? First, Washington and Seoul must make every effort to avoid war in the current crisis. The United States is undoubtedly (and appropriately) quietly reinforcing U.S. forces in the region, and the CFC is understandably considering what red lines might trigger a pre-emptive conventional strike. But the fact that war with North Korea probably means nuclear war should temper any consideration of limited pre-emptive strikes. Pre-emption means war, and war means nuclear.

Second, U.S. and South Korean planners need to develop truly limited conventional military options for the Peninsula—limited not merely in their objectives but also in terms of the military operations they unleash. Perhaps the greatest danger of all is if the U.S. president and the South Korean president incorrectly believe that they have limited military options available; they and their senior advisers may not fully appreciate that those supposedly limited options in fact entail hundreds of airstrikes against high-value targets, such as leadership, command-and-control systems, and perhaps even against nuclear-weapons sites.

Third, American and South Korean leaders should urge China to develop “golden parachute” plans for the North Korean leadership and their families. Leaders in Pyongyang will keep their nuclear weapons holstered during a war only if they believe that they and their families have a safe and secure future somewhere. In the past, China has been understandably reluctant to hold official talks with the United States about facilitating the demise of its ally. But the prospect of nuclear war next door could induce Beijing to take more direct steps, including preparing an escape plan now and revealing it to Kim as soon as a first shot is fired.

More broadly, the strategic dilemma Washington faces today extends beyond the current standoff with North Korea: how to run a network of global alliances when nuclear weapons allow enemies to nullify the United States’ superior military might. American officials used to extol the ability of nuclear weapons to stalemate powerful enemies. Now the shoe is on the other foot. There is every reason to believe that North Korea has adopted NATO’s old strategy. As the current standoff is making frighteningly clear, deterring escalation, especially during conventional wars, is not last century’s concern; it may be the single toughest strategic problem confronting the United States for decades to come.

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  • KEIR A. LIEBER is an Associate Professor in the Edmund A. Walsh School of Foreign Service and Department of Government at Georgetown University.
    DARYL G. PRESS is an Associate Professor in the Government Department at Dartmouth College and Coordinator of War and Peace Studies at Dartmouth’s John Sloan Dickey Center for International Understanding.
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