Q. For how long have chemical weapons been considered an especially egregious type of warfare, and in what form have we seen these objections raised?
A. The taboo against chemical weapons in battle is very old, and can really be traced back to ancient history, when the use of poisons was considered a treacherous and dishonorable form of warfare. The international community first attempted to pass a systematic ban in the 1899 Hague Declaration Concerning Asphyxiating Gases. But that was evaded or violated during World War I — first by the Germans at Ypres in April 1915, and then by all the major powers.
After 1918, poison gas became the key symbol of the war’s brutality and devastation. And so there were efforts to restrict the development or use of chemical weapons, a movement that included not only diplomats but nongovernmental organizations, church groups, journalists and ordinary citizens.
What we have seen in the last 30 years is a push for the restriction on battlefield use to be widened, with the recognition that civilian populations are particularly vulnerable to chemical attacks. Currently, the international community is governed by the Chemical Weapons Convention, which went into force in 1997 — although Syria is not a signatory to the convention.
Q. In military history, to what extent have countries tended to adhere to bans on chemical weapons?
A. Over the course of the 20th century, countries have often chosen not to use chemical weapons, for three main reasons. First, they were afraid that the weapons would be used against their soldiers in retaliation. Second, they calculated that chemical weapons wouldn’t yield a tactical advantage on the battlefield: You might gas your own soldiers, or make a terrain uninhabitable, or if your enemies have gas masks or other defensive capabilities, that would minimize the weapons’ impact.
But the third main reason why countries have chosen not to use chemical weapons is, for me, the most important one: that they fear condemnation and sanction from their enemies or even their own populations. Leaders have typically ordered their use only in desperation — or in situations when they think the world isn’t watching. War is a battle for hearts and minds as much as a conflict of arms, and the use of chemical weapons means ceding a great deal of moral territory for modest gains on the battlefield. That’s a point that could apply to nonstate actors and terrorist organizations as well as to governments.
So have chemical-weapons bans worked? No and yes. The conventional wisdom holds that “treaties don’t work, but chemical weapons don’t work either.” But I think that overlooks the importance of public opinion and activism around shared values. True, treaties and protocols have been unsigned, unratified or violated by some countries. But they have succeeded in expressing a clear international norm against forms of warfare that have devastating effects on soldiers, civilians and natural environments. And if people had not spoken up to insist that chemical weapons were wrong, then these global norms would not exist.
Q. What does history tell us about the kinds of responses countries make to violations of chemical weapons bans? Do these responses tend to be military in nature, diplomatic, economic — or some combination of these things?
A. When President Obama talks of Syrian chemical-weapons development as a “red line,” and Secretary of State John Kerry refers to a line “which has been in place since the horrors of World War I,” they are making historical claims. They are correct to say that international norms view the use of chemical weapons — whether against soldiers or civilians — as unacceptable, and that some kind of response is necessary. But while the world must respond in some fashion to recent events in Syria, history does not show that the use of chemical weapons has always — or even often — generated a military response. Diplomatic initiatives and economic sanctions remain on the table.