Russian authorities recently threatened to aim nuclear missiles at Danish warships if Denmark joins NATO's missile-defense system. This was obviously an outrageous threat against a country that has no intention of attacking Russia. But it also reflects a more fundamental factor in the Kremlin's foreign policy: desperation to maintain Russia's strategic influence at a time of unprecedented challenges to its authority.

Of course, Russia's leaders know very well that NATO's missile defense is not directed at their country. When I served as NATO secretary general from 2009 to 2014, we repeatedly emphasized that the purpose was to defend alliance members from threats originating outside the Euro-Atlantic area. Anyone with even a rudimentary knowledge of physics and engineering — two subjects at which Russians excel — can see that the system is designed to do precisely that.

Russia's nuclear threats, against Denmark and others, are the hallmark of a weak country in economic, demographic and political decline. NATO has not aggressively victimized Russia, as Kremlin propaganda claims. The current conflict between Russia and the West — centered on the crisis in Ukraine — is, at its core, a clash of values.