If I had told you two years ago that in 2022 the president of the United States would be heard babbling inanely about the risk of “Armageddon” during an international crisis, you would have said, “So Trump won the election, huh?”

He didn’t. It was the other non compos mentis septuagenarian on the ballot who won. You know, the old pro who’s been in Washington since the Nixon era and who would, we were assured, be too savvy to blather his way into needless provocations toward belligerents.

The advisability of Joe Biden’s chitchat with Democratic donors aside, he’s not crazy to believe that a single small “tactical” nuclear detonation by Russia in Ukraine might lead the war to spiral quickly under the logic of deterrence. If Russia went nuclear, Ukraine’s allies would need to respond lest other rogue powers conclude there’s no price to pay for using weapons of mass destruction. Once those allies responded, the Kremlin might feel obliged to escalate further to prove to its own allies and to Putin’s domestic subjects that Russia won’t be cowed by Western military might. That escalation might mean further nuclear use, which would then require an expanded Western response. The only limit on where the cycle of retaliation goes from there is the darkness of one’s own imagination.

A strange game. The only winning move is not to play. But what if Putin insists on playing?