Would Russia use nuclear weapons in Ukraine? A number of people have approached this question boldly in recent days and have boldly asserted that we don’t know. I join in that conclusion, but it’s always interesting to work through the argument.

Over the past year, I’ve been reading Fred Kaplan’s The Wizards of Armageddon closely. It’s a history of the development of nuclear strategy. A great many of the recent articles have reproduced that development in short form. That’s because, I would argue, there’s not much to nuclear strategy. Clausewitz tells us that it’s easy for war to run out of control. When the weapons of war are potentially world-ending, it is essential that war not run out of control. That limits actions and responses.

The deterrence properties of those weapons have been working in Russia’s war against Ukraine. Part of the reason NATO has not joined the war directly is that its entry would move everything too much closer to a nuclear exchange. Similarly, Russia has not attacked NATO members. Nuclear deterrence limits the geographic scope of the war.

Russia’s stated threshold for nuclear weapons use is “an existential threat to the country.” Given Putin’s rhetoric about the reasons for making war on Ukraine, it is hard to know what he considers an existential threat to Russia. Although he has claimed that Ukraine’s sovereignty poses an existential threat to Russia, he allowed his military to back off from a general conquest of Ukraine when it looked like that would not work. There is evidently some flexibility in Putin’s understanding of that phrase.

What happens if the war starts going very badly for Putin? If it looks, say, like Russian ammunition is running out and Ukrainian troops are pushing Russian troops toward the border? Might Putin consider using a nuclear weapon to change the course of the war?

This article gives a bit of the historical background on nuclear strategy and lays out the options clearly, although leaning toward the military ones. Let’s say Russia drops a small nuclear weapon on, say, the Zaporizhzhye nuclear plant. What are NATO’s response options? I say NATO because they’re the ones with nuclear weapons, not Ukraine.

• Do not strike back, but proclaim Russian inhumanity in using nuclear weapons
• Nuclear attack on an equivalent target within Russia
• Escalate a nuclear attack to a higher-value target
• Strike with a conventional force

The downsides, respectively, are

• Russia may take this as having a free hand to attack its neighbors.
• Could go into a slow-motion tit for tat situation or escalate to more nuclear use.
• Very likely to escalate.
• Nuclear escalation possible, but less likely.

The last seems to be the most likely NATO response, although much depends on specifics.

These options add up to everything that is possible in a nuclear war that starts on the battlefield, rather than a transcontinental attack. Even there, the options are similar.

Nuclear strategists have been struggling with the simplicity of this pattern since the first bombs were dropped in 1945. They have not come up with new answers. The edgier among them like to try to game out scenarios involving a few small hits, which involve enormous assumptions as to the fear or good will of the other side. Usually they will lament the American lack of tactical nuclear weapons in contrast to Russia’s two thousand or so. But those “small” weapons might be the size of the Hiroshima and Nagasaki weapons. Too small, and there’s not much difference in destruction from conventional weapons. Larger, and at some point someone is likely to target beyond the battlefield.

The two atom bombs dropped by the US on Japan were the only ones in existence at that time. Nobody could retaliate. But that’s no longer the case. And, just as in any war scenario, much depends on the specifics of the situation and the people involved, perhaps even more so with nuclear weapons. Right now, it looks like we’re a long way from nuclear weapon use.

Cross-posted to Lawyers, Guns & Money