During WWII, everyone seems to have expected the use of chemical weapons, but never actually found a situation where doing so was advantageous. This is often phrased in terms of fears of escalation (this usually comes packaged with the idea of MAD (Mutually Assured Destruction), but that’s an anachronism – while Bernard Brodie is sniffing around the ideas of what would become MAD as early as ’46, MAD itself only emerges after ’62). Retaliation was certainly a concern, but I think it is hard to argue that the combatants in WWII hadn’t already been pushed to the limits of their escalation capability, in a war where the first terror bombing happened on the first day. German death-squads were in the initial invasion-waves in both Poland, as were Soviet death squads in their invasion of Poland in concert with the Germans and also later in the war. WWII was an existential war, all of the states involved knew it by 1941 (if not earlier), and they all escalated to the peak of their ability from the start; I find it hard to believe that, had they thought it was really a war winner, any of the powers in the war would have refrained from using chemical weapons. The British feared escalation to a degree (but also thought that chemical weapons use would squander valuable support in occupied France), but I struggle to imagine that, with the Nazis at the very gates of Moscow, Stalin was moved either by escalation concerns or the moral compass he so clearly lacked at every other moment of his life.

Both Cold War superpowers stockpiled chemical weapons, but seem to have retained considerable ambivalence about their use. In the United States, chemical weapons seem to have been primarily viewed not as part of tactical doctrine, but as a smaller step on a nuclear deterrence ladder (the idea being that the ability to retaliate in smaller but still dramatic steps to deter more dramatic escalations; the idea of an “escalation ladder” belongs to Herman Kahn); chemical weapons weren’t a tactical option but baby-steps on the road to tactical and then strategic nuclear devices (as an aside, I find the idea that “tactical” WMDs – nuclear or chemical – could somehow be used without triggering escalation to strategic use deeply misguided). At the same time, there was quite a bit of active research for a weapon-system that had an uncertain place in the doctrine – an effort to find a use for a weapon-system the United States already had, which never quite seems to have succeeded. The ambivalence seems to have been resolved decisively in 1969 when Nixon simply took chemical weapons off of the table with an open “no first use” policy.

Looking at Soviet doctrine is harder (both because I don’t read Russian and also, quite frankly because the current epidemic makes it hard for me to get German and English language resources on the topic) The USSR was more strongly interested in chemical weapons throughout the Cold War than the United States (note that while the linked article presents US intelligence on Soviet doctrine as uncomplicated, the actual intelligence was ambivalent – with the CIA and Army intelligence generally downgrading expectations of chemical use by the USSR, especially by the 1980s). The USSR does seem to have doctrine imagine their use at the tactical and operational level (specifically as stop-gap measures for when tactical nuclear weapons weren’t available – you’d use chemical weapons on targets when you ran out of tactical nuclear weapons), but then, that had been true in WWII but when push came to shove, the chemical munitions weren’t used. The Soviets appear to have used chemical weapons as a terror weapon in Afghanistan, but that was hardly a use against a peer modern system force. But it seems that, as the Cold War wound down, planners in the USSR came around to the same basic idea as American thinkers, with the role of chemical weapons – even as more and more effective chemicals were developed – being progressively downgraded before the program was abandoned altogether.

This certainly wasn’t because the USSR of the 1980s thought that a confrontation with NATO was less likely – the Able Archer exercise in 1983 could be argued to represent the absolute peak of Cold War tensions, rivaled only by the Cuban Missile Crisis. So this steady move away from chemical warfare wasn’t out of pacifism or utopianism; it stands to reason that it was instead motivated by a calculation as to the (limited) effectiveness of such weapons.

And I think it is worth noting that this sort of cycle – an effort to find a use for an existing weapon – is fairly common in modern military development. You can see similar efforts in the development of tactical nuclear weapons: developmental dead-ends like Davy Crockett or nuclear artillery. But the conclusion that was reached was not “chemical weapons are morally terrible” but rather “chemical weapons offer no real advantage”. In essence, the two big powers of the Cold War (and, as a side note, also the lesser components of the Warsaw Pact and NATO) spent the whole Cold War looking for an effective way to use chemical weapons against each other, and seem to have – by the end – concluded on the balance that there wasn’t one. Either conventional weapons get the job done, or you escalate to nuclear systems.

(Israel, as an aside, seems to have gone through this process in microcosm. Threatened by neighbors with active chemical weapons programs, the Israelis seem to have developed their own, but have never found a battlefield use for them, despite having been in no less than three conventional, existential wars (meaning the very existence of the state was threatened – the sort of war where moral qualms mean relatively little) since 1948.)

And I want to stress this point: it isn’t that chemical munitions do nothing, but rather they are less effective than an equivalent amount of conventional, high explosive munitions (or, at levels of extreme escalation, tactical and strategic nuclear weapons). This isn’t a value question, but a value-against-replacement question – why maintain, issue, store, and shoot expensive chemical munitions if cheap, easier to store, easier to manufacture high explosive munitions are both more obtainable and also better? When you add the geopolitical and morale impact on top of that – you sacrifice diplomatic capital using such weapons and potentially demoralize your own soldiers, who don’t want to see themselves as delivering inhumane weapons – it’s pretty clear why they wouldn’t bother. Nevertheless, the moral calculus isn’t the dominant factor: battlefield efficacy – or the relative lack thereof – is.

Bret Devereaux, “Collections: Why Don’t We Use Chemical Weapons Anymore?”, A Collection of Unmitigated Pedantry, 2020-03-20.