Among the many disturbing legacies of Russia’s invasion of Ukraine, one of the most alarming is its seeming confirmation of the utility of nuclear weapons.

The war has given policymakers and publics reason to believe that a nuclear arsenal contributes to national security. If those conclusions go unchallenged, nuclear proliferation is likely to follow. Nothing could be more dangerous.

The nuclear shadow has clouded the Ukraine conflict. Weeks before the invasion, Russia conducted maneuvers with its nuclear forces which, when combined with the marshaling of its military on the Ukraine border, signaled Moscow’s readiness to fight with all its capabilities. Shortly after the invasion began, Russian President Vladimir Putin said that he was putting his country’s “deterrent forces” — its nuclear weapons — on “a special regime of alert” and warned that intervention by the West would lead to “consequences you have never seen.”