This is what makes the crisis over Ukraine such a pivot in history. It marks the definitive end of the post-Cold War era, the short period in which the West could, with steadily diminishing conviction over a generation, reasonably claim to have achieved the triumph of its values.

Any vestige of belief in the idea that the age of ideological conflict is over seems to be gone. We lost the post-Cold War.

I’ll willingly concede that this may prove too bleak an assessment. We don’t yet know the outcome of Mr. Putin’s gambit in Eastern Europe. It’s possible he’s miscalculated. Russia’s economic challenges—blighted demographics, an overdependence on energy, endemic kleptocratic corruption—are masked by the nation’s renewed sense of strategic self-worth. Just as the Soviet Union turned out to be, in the words of a British observer, Ivory Coast with nuclear weapons, so Mr. Putin’s Russia might ultimately prove a Potemkin superpower. Perhaps a Ukrainian campaign will be Mr. Putin’s Afghanistan…

The larger problem is that we in the West, in the U.S. especially, have been losing the war from within. Victory in the Cold War bred complacency, a loss of a defining sense of purpose. We failed to meet the most basic needs of many citizens for economic security, opportunity and belonging and in the process stoked resentment and political backlash. We failed to remember, respect and preserve the civilizational virtues that had driven our victory in the first place. We failed repeatedly in expeditions overseas.