The answer is straightforward: For Ukraine to be truly free and independent, it will have to be a member of the European Union and NATO. Although Moscow will no doubt object, Putin’s brutal aggression makes clear that only European countries that are members of NATO can be truly secure. And NATO should welcome Ukraine into the fold.

Ironically, Moscow’s unprovoked aggression is proof that its long-standing complaint about NATO moving too close to its borders was little more than a convenient excuse for its revisionist aims. The alliance posed no threat to Russia, and prior to the war, President Joe Biden and other NATO leaders made clear that they would not come to Ukraine’s defense. Had Ukraine been a member, however—alongside the Baltic states and all non-Soviet members of the Warsaw Pact—Russia would have been unlikely to invade for fear of a wider military confrontation that it would surely have lost. Far from NATO being the proximate cause of war, NATO’s absence enabled Putin to act.

Since February 24, when Putin invaded, many European nations have undergone a wholesale reevaluation of their security needs. Germany now understands that dialogue and trade are no substitute for deterrence and defense when it comes to dealing with an autocratic country like Russia. Finland and Sweden are on the verge of joining NATO, something few experts had thought possible before the invasion, given their centuries of neutrality and independence. Others are increasing defense spending, dispatching weapons to Ukraine, and bolstering the forward military presence in NATO’s eastern flank.