Is the Treaty Banning Nuclear Weapons Immoral?


War is an ugly thing, but not the ugliest of things: the decayed and degraded state of moral and patriotic feeling which thinks that nothing is worth a war, is much worse…. A man who has nothing which he is willing to fight for, nothing which he cares more about than he does about his personal safety, is a miserable creature who has no chance of being free, unless made and kept so by the exertions of better men than himself.

-J.S. Mill, 1881 Principles of Political Economy

If there was a lawful way to inflict terrible harm on a ruthless enemy bent on the enslavement or even the extermination of your citizenry, would you use it even if there was great risk involved? Do you agree with legendary Mexican revolutionary Emiliano Zapata, who famously said, “It is better to die on your feet than to live on your knees”? I suspect many War on the Rocks readers do, but around the globe there are significant numbers who seem to disagree. There are, apparently, 122 nations who would submit to a merciless enemy before allowing a legitimate weapon to save them.

That’s the number of countries that agreed to the text of the newly-drafted Treaty on the Prohibition of Nuclear Weapons (which opens for formal ratification in September). Among other things, it says that each party “undertakes never under any circumstances to…[u]se or threaten to use nuclear weapons or other nuclear explosive devices.” (Emphasis added.)

As someone who served in three commands focused on nuclear operations, I have no illusions about the horrific destructiveness of these weapons. Unquestionably, any use of them would be a terrible event and raise deep moral questions. Yet I would never agree that a treaty is “moral” if it forbids, even as a last resort in the most extreme situation, a defensive measure that both law and ethics permit.

Can you support a treaty that seeks to close off any usage of nuclear weapons, even to stop, for example, a genocidal maniac bent on the destruction of humankind?

That is what this treaty could do by outlawing weapons international law has never prohibited. In 1996, the International Court of Justice concluded in an advisory opinion on the legality of nuclear weapons that there is in “neither customary nor conventional international law any comprehensive and universal prohibition of the threat or use of nuclear weapons as such.” Further, the court could not say “whether the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defence, in which the very survival of a State would be at stake.”

Of course, the moral issue matters. While absolute pacifists may think otherwise, most of the world looks to Just War theory for the moral underpinnings of the use of force. There are various formulations of Just War theory, but all include some expression of this concept found in Catholic Just War theory:

The use of arms must not produce evils and disorders graver than the evil to be eliminated. The power of modem means of destruction weighs very heavily in evaluating this condition.

The moral arguments of the treaty advocates seem to center around this part of Just War theory. For example, the International Campaign to Abolish Nuclear Weapons (ICAN) argues:

Any use of nuclear weapons would have catastrophic consequences. No effective humanitarian response would be possible, and the effects of radiation on human beings would cause suffering and death many years after the initial explosion. Prohibiting and completely eliminating nuclear weapons is the only guarantee against their use.

Along similar lines, ICAN also claims that “any use of weapons would violate international humanitarian law because they would indiscriminately kill civilians and cause long-term environmental harm.”

But it is simply not true that “any” use of nuclear weapons would inevitably violate international humanitarian law. As former National Security Council staffer Paul Miller points out, “nuclear bombs come in a wide range of sizes” and certain uses may result in little or no civilian harm. He says:

Although any nuclear weapon would have a high likelihood of causing some civilian casualties unless used in open desert or the ocean, the degree of civilian harm might be relatively small if the nuclear warhead is small enough and the location relatively remote (i.e., not a city). If the target is a major enemy asset, such as a tank division, an aircraft carrier, a headquarters bunker, or a nuclear weapons arsenal, the military value might outweigh the potential harm to civilians.

In such a scenario, nuclear weapons could meet the Just War theory criterion that the weapon not cause more destruction than the harm it is addressing.

And there is more to Just War theory. It also mandates efforts to defend the helpless. In their 2016 book, Necessity in International Law, Jens Ohlin and Larry May point out that “[t]raditional Just War theory argues that some wars can be justified, even required, out of respect for the protection of innocent life.” (Emphasis added.) This comports with Catholic Just War Doctrine, which says:

Legitimate defense can be not only a right but a grave duty for one who is responsible for the lives of others. The defense of the common good requires that an unjust aggressor be rendered unable to cause harm. For this reason, those who legitimately hold authority also have the right to use arms to repel aggressors against the civil community entrusted to their responsibility. (Emphasis added.)

Some ethicists like Michael Walzer argue that ‘[n]uclear war is and remains unacceptable” because the weapons create a “new kind of war.” However, philosopher Alexander Moseley counters with a stronger analysis:

Against Walzer, it can be reasonably argued that although such weapons change the nature of warfare (for example, the timing, range, and potential devastation) they do not dissolve the need to consider their use within a moral framework: a nuclear warhead remains a weapon and weapons can be morally or immorally employed.

Furthermore, the employment of nuclear weapons may actually support another key tenet of Just War theory: To be moral, the use of force must have a reasonable chance of success. Could there be situations in which the use of nuclear weapons is the most feasible way to produce a reasonable chance of military success? Could there be legitimate military targets that actually require nuclear weapons for their destruction? In fact, yes.

Imagine that the only way to halt the genocidal depredations of an enemy leader is to neutralize him in his command post tunneled deep into a mountain. In its 2005 study, Effects of Nuclear Earth-Penetrator and Other Weapons, the National Research Council of the National Academies concluded:

Many of the more important strategic hard and deeply buried targets (HDBTs) are beyond the reach of conventional explosive penetrating weapons and can be held at risk of destruction only with nuclear weapons.

Nuclear weapons may also be the only practical means of achieving the high temperatures needed to assure the timely destruction of a virulent and lethal pathogen that an enemy might develop. Additionally, some believe that nuclear weapons could be the “best answer” to destroy or divert a cataclysmic meteor or asteroid hurtling towards earth.

To be sure, the legal and moral use of a nuclear weapon must comply with the targeting principles of international humanitarian law, such as the requirement of distinction (which means that except in the case of belligerent reprisal, you must target combatants and not noncombatants or their property). The law – like Just War theory – also requires strict observance of the principle of proportionality, that is, any civilian losses must not be excessive in relation to the anticipated military advantage sought from the attack. The Department of Defense Law of War Manual is in accord, insisting that the “law of war governs the use of nuclear weapons, just as it governs the use of conventional weapons.”

Obviously, non-legal but essential real-world considerations such as escalation control have to be taken into account in any contemplated use of nuclear weapons. But the point is that it is wrong to categorically preclude use of the weapons in all cases, even when doing so would be strategically, politically, and ethically prudent, and fully consonant with the law.

Moreover, from a moral perspective, ban advocates have to confront this inconvenient fact: As military historian Martin Van Creveld pointed out in 1996, as “the power of nuclear weapons grew—from 20,000 kilotons in 1945 to 58 megatons in 1961—and their numbers increased, wherever they made their appearance large-scale interstate war came to a halt.” The United States, Britain, and France reiterated that point in their recent statement, saying “the ban treaty is incompatible with the policy of nuclear deterrence, which has been essential to keeping the peace in Europe and North Asia for over 70 years.” Isn’t a just peace the ultimate aim of Just War theory?

Beyond the conceptual moral issues, there are practical and political problems with the treaty as well. According to reports, “some states have expressed hope that [the treaty as a] normative statement might contribute to the development of parallel customary international law.” Customary international law ordinarily operates to bind all nations, even those who are not parties to a given treaty.

Customary international law already governs much of the United States’ military conduct. Although not a party to Protocol I of the Geneva Conventions, (which includes various rules about targeting), the United States nevertheless considers itself bound by a significant part of it. However, the United States, France, and Britain have already taken steps to prevent the ban treaty from evolving into customary international law. Their statement established themselves as “persistent objectors” to the treaty (which means they would not be bound if a customary norm emerged.) The three nations said:

We do not intend to sign, ratify or ever become party to it…we would not accept any claim that this treaty reflects or in any way contributes to the development of customary international law.

The statement also recognizes the proverbial “elephant in the room” by pointing out that the treaty offers “no solution to the grave threat posed by North Korea’s nuclear program.” It argues that instead of enhancing peace and security, the treaty creates “even more divisions at a time when the world needs to remain united in the face of growing threats” like those posed by Kim Jong Un.

This is not to suggest that the United States or its allies consider these weapons in anything but the gravest terms. For example, in the Nuclear Posture Review, the Department of Defense said the United States “would only consider the use of nuclear weapons in extreme circumstances to defend the vital interests of the United States or its allies and partners.” Yet under the treaty, parties would be unable to seek the protection of the U.S. nuclear umbrella with its implicit threat to use the weapons if necessary.

Why? Under the pact each country also agrees “never under any circumstances to…[a]ssist, encourage or induce, in any way, anyone to engage in any activity prohibited to a State Party under this Treaty.” The United States, according to the Washington Post, has “some form of defense pact” with 69 countries whose populations comprise about a quarter of humanity.

In a very fundamental way, the premise of the treaty – that nothing, even freedom, presumably, is worth using nuclear weapons to defend – is at odds with what many Americans believe. In a 2016 poll, only 17% of Americans agreed with language very much like that of the treaty: that the “U.S. should never use nuclear weapons under any circumstances.” And let’s not forget that there are some seventy nations – including, interestingly, Japan – who are not signing the treaty.

Americans are not naïve about the risks nuclear weapons pose, but they have long valued freedom over safety. Nuclear weapons can defend not just lives, per se, but a way of life. But it seems treaty advocates prefer to avoid the risks that nuclear weapons might pose, even at the possible cost of freedom. Even accounting for the very real perils nuclear weapons entail, is there really nothing worth defending with them? No circumstance worthy of their use? Philosopher John Stuart Mill’s observation that leads this essay remains apropos today.

The millions of people in those 122 nations should hope there are others willing to make the exertions to rescue them should the “any circumstances” referred to in the treaty become a cruel reality in which their freedom, or their very existence, is imperiled by the worst kind of malevolence.


Charles Dunlap is currently a Professor of the Practice and Executive Director of the Center on Law, Ethics and National Security at Duke Law School. He retired from the Air Force in 2010 as a major general, and over his 34-year career he served as a military judge, prosecutor, and defense counsel, as well as the Chief of the Military Justice Division at the Air Force Judge Advocate General School.

Image: U.S. Air Force