“The worst does sometimes happen.”

— Friedrich Durrenmatt, Swiss playwright


Seeking to dissuade North Korean leader Kim Jung Un from continuing nuclearization, US President Donald Trump has relied largely upon various economic incentives. Still, the North Korean dictator is less likely to be motivated by any American promises of enhanced national wealth and well-being than by thoughts of expanded personal power. It follows, going forward, that the US position should be more expressly oriented toward making optimal use of exactly these kinds of self-centered thoughts.

Reasonable foreign policies require reasonable objectives. Accordingly, President Trump must begin to think along realistic lines of achieving long-term nuclear deterrence with his eccentric adversary in Pyongyang. In this connection, and as all US intelligence agency heads have several times agreed, there are no conceivable circumstances wherein it could make strategic sense for North Korea to surrender its nuclear weapons or supporting infrastructures.

After all, these particular assets remain that country’s most conspicuous bases of global influence and power.

There is more. During any still-upcoming negotiations, President Trump should take scrupulous care not to exaggerate or overstate America’s military risk tolerance. Such recommended diplomatic caution would derive in part from the absence of any historically comparable crises.

To the extent that there has never been a nuclear war, there could be no imaginable way for Mr. Trump to determine the probability of a US-North Korea nuclear conflict. (The atomic bombings of Japan in August 1945 do not properly constitute a nuclear war, but “only” the use of nuclear weapons in an otherwise conventional conflict. Significantly, too, following Hiroshima and Nagasaki, there were no other atomic bombs still available anywhere on earth.)

For the American president, this unequivocal observation could seem both sobering and stark, but it is nonetheless incontestable. In any true scientific assessments, meaningful mathematical probabilities must always be drawn from the ascertainable frequency of pertinent past events. This does not mean that Trump’s senior strategists and counselors should steer away from clear-eyed assessments regarding nuclear costs and risks (quite the contrary), but rather that such assessments must be drawn from constantly shifting and hard-to-decipher geopolitical trends.

Other factors must also arise. President Trump should bear in mind that many or all of these continuously transforming and mutating developments will be impacted by “Cold War II,” an oppositional stance already well entrenched with Russia, and—more or less derivatively—with China. Similarly important will be the US leader’s willingness to recognize certain consequential limits of military advice.

These generally unseen limits are assuredly not based upon any presumed intellectual inadequacies, but only on the indisputable knowledge that no person has ever fought in a nuclear war. In essence, there are no experts on the subject of a nuclear war.

By definition—going forward with time-urgent considerations of US-North Korea policy—all major US strategic calculations will be fraught with variously intersecting and continuously daunting uncertainties. Still, it will be absolutely necessary that Donald Trump and his counselors remain able to offer their best available war estimations. Among prospectively causal factors—some of them overlapping, interdependent, or “synergistic”—the calculable risks of a nuclear war between Washington and Pyongyang will depend upon whether such a conflict would be intentional, unintentional, or accidental.

In principle, at least, this tripartite strategic distinction could prove very important to any hoped-for success in relevant US nuclear war prediction and prevention processes.

Facing future North Korean negotiations, it will be necessary that competent US policy analysts systematically examine and measure foreseeable dynamic configurations of nuclear risk. Expressed in the game-theoretic parlance of formal military planning, these shifting configurations could present themselves singly or one at a time (the expectedly best case for Washington), but they might also arise more or less suddenly, unexpectedly, with apparent diffusiveness, and even in multiple or overlapping “cascades” of strategic complexity.

To properly understand such bewildering cascades will require carefully honed, well-developed and formidable analytic skills. Consequently, this will not be a suitable task for the intellectually fainthearted. On the contrary, it will require generally rare combinations of historical acquaintance, traditional erudition, and demonstrated capacities for advanced dialectical thinking.

In essence, this task will require thinkers who are as comfortable with the challenging prescriptions of Plato and Descartes as with the more narrowly technical elements of modern strategic theory and associated military hardware.

There is more. It is conceivable that neither Washington nor Pyongyang is currently paying sufficient attention to the specific and residual risks of an unintentional nuclear war. To this point in their prospectively ongoing summitry, each leader would seem to assume the other’s complete decisional rationality. If, after all, there were no such mutual assumption, it could make no sense for either side to negotiate any further security accommodations with the other.

Viable deterrence must be the overriding US strategic goal with North Korea. But this complex goal is always contingent upon certain basic assumptions concerning enemy rationality. Are such assumptions realistically valid in this particular case of potential war between already nuclear powers? If President Trump should sometime begin to fear enemy irrationality in Pyongyang, issuing new threats of US retaliation might make only diminishing sense.

At that unprecedented stage, American national security could come to depend upon some presumptively ideal combinations of ballistic missile defense and defensive first strikes. Again by definition, determining such bewildering combinations would lack decisional input from any concrete or quantifiable historical circumstances.

In the conceivably worst case, the offensive military element could entail a narrowly situational or comprehensive preemption—a defensive first strike—but at that manifestly late stage all previous hopes for bilateral reconciliation would already have become moot. There could then obtain no “ordinary” circumstances wherein a preemptive strike against a nuclear adversary such as North Korea would be rational.

None of these difficult decisions could be reached casually or easily. With the steadily expanding development of “hypersonic” nuclear weapons, figuring out optimal US policy combinations from one crisis to another could quickly become overwhelming. Also, though counterintuitive amid such foreseeable complications, the evident fact that one “player” (the United States) is recognizably “more powerful” than the other (North Korea) could prove to be largely irrelevant.

In all such foreseeable circumstances, there would be certain overlapping issues of law and strategy. Under international law, which remains an integral part of US law, the option of a selective or comprehensive defensive first strike might sometime be correctly characterized as “anticipatory self-defense.” But this would be the case only if the American side could argue coherently and persuasively that the danger posed by North Korea was imminent. Such discernible “imminence” is specifically required by the authoritative standards of international law—that is, by criteria established after an 1837 naval incident famously called the Caroline case.

Now, moreover, in the nuclear age, offering aptly precise characterizations of “imminence” could prove sorely abstract and densely problematic.

For the moment, it seems reasonable that Kim Jung Un would value his own personal life and that of his nation above literally any other imaginable preference or combination of preferences. In any corresponding scenario, Kim is visibly and technically rational, and must thus remain subject to US nuclear deterrence. Nonetheless, it could still become important for a negotiating American president to distinguish between authentic instances of enemy irrationality and merely pretended irrationality.

In the past, President Trump himself has praised pretended irrationality as a potentially useful US national security strategy. Apropos of this praise, his earlier “fire and fury” warnings might have reflected a prospective “rationality of pretended irrationality” posture for the United States. Ultimately, however, such a posture could be adopted by either one or both sides.

This prospect adds yet another layer of complexity to the subject at hand, one that could also include certain force-multiplying synergies.

Although neither side would likely seek a shooting war in some form or other, either or both heads of state could still commit catastrophic errors in rendering their decisive strategic calculations. Such possibly grievous errors would represent an unintended consequence of jointly competitive searches for “escalation dominance.” Arguably, such crucial errors are more apt to occur in those particular circumstances where one or both leaders had first chosen to reignite hyperbolic verbal rhetoric.

Significantly, even in reassuringly calm periods of polite and congenial diplomatic discourse, major miscalculations, accidents, or “cyber-confusions” could accumulate. Rapidly.

What then?

In certain worst-case scenarios, negotiations gone wrong could result in a genuinely nuclear war.

An inadvertent nuclear war between the United States and North Korea could take place not only as the result of various misunderstandings or miscalculations between rational national leaders, but also as the unintended consequence (singly or synergistically) of mechanical, electrical, or computer malfunctions, or of certain “hacking”-type interventions. Going forward, these interventions could even include the unprecedented intrusions of “cyber-mercenaries.”

In any still-impending crisis between Washington and Pyongyang, each side will expectedly strive to maximize two critical goals simultaneously. These goals are: (1) to dominate the dynamic and largely unpredictable process of nuclear crisis escalation; and (2) to achieve desired escalation dominance without sacrificing any vital national-security obligations. In the final analysis, this second objective means preventing one’s own state and society from suffering any catastrophic or existential harms.

This brings up a prior point concerning all obligatory assessments of relative military power. When President Trump, in an earlier verbal competition with Kim Jung Un, stated that the North Korean president may have his own nuclear button, but that his American button was bigger, the US leader revealed a major conceptual confusion. It is that today, in the still advancing nuclear age, atomic superiority is potentially per se insignificant and could sometime lead the seemingly stronger nuclear adversary toward variously lethal expressions of diplomatic overconfidence.

In essence, in certain circumstances, even an enemy with a smaller “nuclear button” could inflict grave harms upon the “stronger” United States and its close allies in Japan, South Korea, or elsewhere.

To wit, North Korea’s 2017 nuclear test had a yield sixteen times larger than the Hiroshima bomb. And that fifteen-kiloton WWII bomb produced tens of thousands of immediate fatalities.

Such vital understanding about available nuclear yield must obtain as long as Kim Jung Un’s “inferior” nuclear arms are judged invulnerable to any American preemptions and seemingly capable of penetrating ballistic missile defenses (whether deployed in the United States, Japan, or South Korea). Because of the extraordinary harms that could be generated by even low-yield nuclear weapons, a small percentage or tiny fraction of Kim’s “inferior” nuclear arsenal could and should appear unacceptably destructive in Washington, Tokyo, or Seoul. Worth noting, too, is that in all of these critical dimensions of strategic judgment, the only reality that would figure in any ongoing adversarial calculations would be perceived reality.

The bottom line of all such informed assessments concerning a still-possible US-North Korea nuclear war is that underlying issues of contention and calculation are enormously complicated. Faced with such daunting measures of complexity—both operational and legal—each side must proceed warily, in a fashion that is both purposeful and risk-averse. Although such prudent counsel may seem to run counter to assorted interlinking obligations of escalation dominance, any upcoming negotiations would involve very deep and uncharted waters.

Looking ahead, any aggressive over-confidence by President Trump or Kim Jong Un will have to be consciously avoided. Although everything at a still-upcoming summit could at first appear simple and calculable, history supports Prussian strategist Carl von Clausewitz’s apt classical observations about “friction,” which, as he reminds us, distinguishes war on paper from war as it actually is. In certain realistic cases, this difference could amount to a total war.

Recalling also the Swiss playwright Friedrich Durrenmatt’s complementary recognition: “The worst does sometime happen.”


Louis René Beres holds a PhD from Princeton University and is Emeritus Professor of International Law at Purdue University. His twelfth and most recent book is Surviving Amid Chaos: Israel’s Nuclear Strategy (Princeton, 2016; 2nd ed. 2018). Some of his principal strategic writings have appeared in Harvard National Security Journal; International Security; Yale Global Online; Oxford University Press; Oxford Yearbook of International Law; Parameters; Special Warfare; The War Room; World Politics; Israel Defense; BESA Perspectives; International Journal of Intelligence and Counterintelligence; the Atlantic; the New York Times; and the Bulletin of the Atomic Scientists. Like the referenced playwright, Friedrich Durrenmatt, Professor Louis René Beres hails originally from Switzerland.

The views expressed are those of the author and do not reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense.