Conventional wisdom dictates that Vladimir Putin has ‘miscalculated’ in his invasion of Ukraine. His blitzkrieg has been poorly executed. He has reinvigorated the Nato alliance and the EU and triggered heavy sanctions. And he has lost the ‘information war’ to Volodymyr Zelensky, the TV comedian turned global hero.

But what if the West has ‘miscalculated’ in reading Putin’s intentions? What if the West’s sanctions, along with intensified military aid to Ukraine and a courageous local resistance, encourage Putin to double down? What if he decides to use a weapon of last resort, a nuclear, chemical or biological weapon, even at...