A detailed blog of potential interest to effective altruists, arguing that chemical (and biological) weapons are rejected by modern militiaries not because of any moral scruples but simply because they are not cost effective. If true, it has depressing implications for our ability to control future dangerous technologies.

Some quotes, but I recommend the whole thing:

Quite frankly, we don’t use chemical weapons for the same reason we don’t use war-zeppelin-bombers: they don’t work, at least within our modern tactical systems.

[T]he modern system relies on cover-and-concealment for survivability and maneuver in the offense

The modern system assumes that any real opponent can develop enough firepower to both obliterate any fixed defense (like a line of trenches) or to make direct approaches futile. So armies have to focus on concealment and cover to avoid overwhelming firepower (you can’t hit what you can’t see!); since concealment only works until you do something detectable (like firing), you need to be able move to new concealed positions rapidly.

Put bluntly: the modern system has few, if any, uses for chemical weapons. Chemical weapons still work against a static-system, but the modern system is already more effective against a static-system in ways that, as we’ll discuss in a moment, chemical weapons cannot enhance.

[I]t is far easier to protect against chemical munitions than against an equivalent amount of high explosives

In order to produce mass casualties in battlefield conditions, a chemical attacker has to deploy tons – and I mean that word literally – of this stuff. Chemical weapons barrages in the first World War involved thousands and tens of thousands of shells – and still didn’t produce a high fatality rate (though the deaths that did occur were terrible). But once you are talking about producing tens of thousands of tons of this stuff and distributing it to front-line combat units in the event of a war, you have introduces all sorts of other problems. One of the biggest is shelf-life: most nerve gasses (which tend to have very high lethality) are not only very expensive to produce in quantity, they have very short shelf-lives. The other option is mustard gas – cheaper, with a long shelf-life, but required in vast quantities (during WWII, when just about every power stockpiled the stuff, the stockpiles were typically in the many tens of thousands of tons range, to give a sense of how much it was thought would be required – and then think about delivering those munitions).

If you want to protect something against high explosives, your only option is armor and lots of it. Heavy, expensive armor. But if you want to protect a soldier against gas? Well, an state-of-the-art M50 gas mask costs about $270 with a set of filters. A complete NBC (Nuclear-Biological-Chemical) suit – for contact-chemicals that the mask doesn’t full protect against – costs a bit less than that (I’ve seen around $200 – and something tells me that researching this has put me on every watchlist). The soldier’s rifle probably costs around $700, for comparison. And remember: these modern system armies have all sorts of hideously expensive hardware. A unit price of c. $500-600 per soldier is cheap. And it makes your entire, very expensive multi-thousand ton arsenal of chemical munitions almost useless at a stroke.

Rich nations can even afford – if they expect chemical attack – to equip their entire civilian populace with these devices.

A modern system army, even if it is on the defensive operationally, is going to want to make a lot of tactical offensives (counterattacks, spoiling attacks). Turning the battle into a slow-moving mush of long-lasting chemical munitions (like mustard gas!) is counterproductive.

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.

[A]s 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.