For centuries before Vladimir Putin arrived on the scene, Russian foreign policy has been shaped by the country’s need for warm-water ports. To be a great power in Europe and the Near East, Russia must have access to the Mediterranean. Commercial as well as military considerations dictate this.

In the eighteenth century Russia conquered the khanate of Crimea and acquired a splendid location for a new Black Sea port — what is now the city of Sevastopol. The Crimean peninsula had been a gateway from Asia to the Mediterranean since the days of the ancient Greeks,...

For centuries before Vladimir Putin arrived on the scene, Russian foreign policy has been shaped by the country’s need for warm-water ports. To be a great power in Europe and the Near East, Russia must have access to the Mediterranean. Commercial as well as military considerations dictate this.

In the eighteenth century Russia conquered the khanate of Crimea and acquired a splendid location for a new Black Sea port — what is now the city of Sevastopol. The Crimean peninsula had been a gateway from Asia to the Mediterranean since the days of the ancient Greeks, who built some of their northernmost colonies there. Russia made Sevastopol the permanent home of its Black Sea Fleet.

When Nikita Khrushchev transferred control of Crimea from Russia to Ukraine in 1954, he merely reshuffled the internal administration of the Soviet Union. After the collapse of the USSR in 1991, the newly independent Ukraine did not move to evict the Russian fleet from its base — at the time it would have been suicidal.

For over twenty years, Ukrainian Crimea continued to host Russia’s most important naval base. But in 2014, after the fall of pro-Russian president Viktor Yanukovych, greater Ukrainian integration into the West seemed in prospect, perhaps even leading to NATO membership. How would that affect Russia’s position in Crimea?

Rather than waiting to find out, Putin annexed the peninsula. But in doing so, he created more problems for Russia than he solved. Crimea was one of the most pro-Russian regions of Ukraine; subtracting its population from the nation’s electorate could only tilt the political balance away from Moscow. Russia’s dismemberment of Ukraine also, of course, further polarized Ukrainian opinion against Russia.

Taking Crimea meant losing Ukraine. So Putin took steps to cripple Ukraine by sponsoring secessionists in the Donbas. Once again, however, Putin created a new problem: the civil war he promoted gave Kyiv the occasion to seek military support from the West. With that support, the Ukrainians could win their war with Russia’s proxies in Donetsk and Luhansk.

Putin had a choice. He could allow his proxies to be defeated, with the attendant blow to Russia’s credibility and the prospect of a strengthened Ukraine eventually turning its attention to Crimea, or he could involve Russia directly in the struggle. If Crimea is vital to Russia’s national interest — which Russian leaders from Catherine the Great onward have believed — then Putin’s decision could only go one way.

He made his fatal mistake in 2014. Rather than relying upon Russia’s economic and political influence in Ukraine to safeguard Russian interests he chose limited war, which is now turning into unlimited war. Russia’s own forces have fared as badly against Ukrainians armed with Western weapons as Russia’s Donbas proxies did earlier. Forced to choose between defeat and escalation, Putin has escalated again, this time with a partial mobilization of Russia’s reserves and threatening words about nuclear weapons.

If the conflict continues to go as badly for Putin as it has until now, we should expect him to escalate further. The one weapon Putin possesses that outclasses anything the West is prepared to give Ukraine is his nuclear arsenal. Some Western analysts believe Putin might employ tactical nuclear weapons, but the use of such devices on the battlefield will not alter the trajectory of the war. If Putin were to use strategic nuclear weapons against western Ukrainian cities, however, the logic of the conflict would instantly change.

We Americans have long told ourselves that our use of nuclear weapons against the civilian populations of Hiroshima and Nagasaki was justified to speedily end a war that otherwise could have dragged on for months, with untold losses of Japanese lives as well as American. If Putin decides to annihilate a city rather than lose the war, he will throw that reasoning in our faces. The West will not accept his excuse, but that will not matter either to the dead or the living. What will matter is what the West and Ukraine do next.

The West will not engage in an all-out superpower nuclear exchange with Russia over the destruction of a city in a state that is not officially a NATO member. But the West might well intensify its support for Ukraine, and if the Ukrainians were willing to continue the fight, Putin would once more have to escalate or risk defeat.

Allies are simultaneously hostages. There is no other state that NATO could strike to force Russia to back down. But Russia can apply pressure to democratic NATO states through nuclear terror. If Russia nuked, say, Tallinn, would Italians or Germans be willing to risk Milan or Frankfurt to have NATO avenge Estonia? And if the Russians made good on the threat to a Western European non-nuclear NATO member, would the nuclear members of NATO then contemplate a superpower nuclear war, or would even the US-UK alliance crack under that strain? At what point does NATO prefer Ukrainian defeat to Armageddon?

The West cannot leave the most consequential decisions for humanity to be made by Moscow. Crimea is hardly the only driver of this conflict, but Russia must be saved from Putin’s mistake, so that Ukraine and the world can be spared an escalatory spiral that has a logic and momentum all its own.

This article was originally published in The Spectator’s November 2022 World edition.