To hear Vladimir Putin say it, Russia is not at war with Ukraine. “I think that this apocalyptic scenario is highly unlikely, and I hope it never comes to that,” Putin said when asked on Russia’s Defender of the Fatherland Day whether his fellow citizens may “wake up one day to learn we are at war” with Ukraine. It can be inferred that the commander-in-chief of the Russian armed force believes (or wants us to believe) that there will be no war between Russia and Ukraine for as long as Moscow refuses to admit to its involvement in the conflict. But is there such a thing as a declared war any more? And how should other European nations respond if they become the target of an undeclared war? What can be done to prevent repetition of the Ukraine scenario elsewhere in Europe?