NATO was meant to be a harbor for the weak and imperiled. It should be again. June’s NATO summit in Madrid was by every account a historic event. In response to Russia’s invasion of Ukraine andbroader belligerence against Europe, NATO unveiled a muscular new strategic concept and invited Finland and Swedento join the alliance—an epochal moment for the two traditionally neutral countries and a major statement for thealliance’s “open door” policy. Yet looming over all of this are the uncertain fates of the two countries most suffering from Russian aggression: Ukraine and Georgia. Both nations were promised membership in the alliance during the 2008 NATO summit in Bucharest, Romania, yet bothremain outside of it. Now, the enormous human and material toll of Russia’s genocidal, neo-imperial war in Ukraine hasput NATO’s extended and unfulfi lled promises into sharp, indelible relief. Obscured by ambiguous technicalities, the alliance’s failure to provide Ukraine and Georgia with a concrete pathway to membership was clearly an unintentional but predictable invitation to Russian aggression. As Ukrainians desperately defend their homeland and count civilians and their children among those killed, the moraland strategic poverty of Ukraine’s deferred accession is laid bare. NATO and its members must now reckon with thewages of a passive approach and rethink the alliance’s founding purpose. The bloc was never meant as an exclusive country club of the rich and strong but rather a harbor for the weak and imperiled. It should be again. In April, while observing the Hungarian parliamentary elections, I saw for myself the heartrending humanitarian crisis on Ukraine’s borders with Hungary and Slovakia. I saw children who had traveled great distances with their families, clutching the meager mementos of home; I met Ukrainians who traveled back and forth across the borders, bringing supplies from the European Union into western Ukrainian cities; and I saw the humanity of volunteers giving some measure of comfort and welcome to weary refugees who had, at long last, reached the promise of safety at the European Union’s frontiers. But what I didn’t see were any great barriers or edifices of geography to suggest the line where, on one side, NATO would risk nuclear war in the people’s defense and on the other side—in Ukraine—it would not. In the United States and Europe, discussions about the borders between NATO and the rest of Europe are treated like immutable features of geography or acts of god, as though certain states and people are afforded divine predestination into the Euro-Atlantic’s rarefied elect. Decisions in the run-up to the war to withhold crucial assistance or provide security guarantees were often justified based on Ukraine’s non-membership in NATO, even though concrete pathways into the alliance have never been offered despite the 2008 declaration. The idea that Ukraine and Georgia were somehow unready or unable to meet NATO’s technical criteria has always been a problematic argument. At no point has NATO established hard, technical benchmarks for membership—clear, achievable standards for entry—and doing so might have risked Ukraine and Georgia passing muster, potentially embarrassing the countries that were categorically opposed to their accession. Realistically, NATO enlargement has always been a political decision. More recent fixations on technical “readiness” and process were introduced after the Cold War to amplify NATO’s turn from a Cold War bulwark to a carrier of Euro-Atlantic values and to manage booming Eastern European demand for membership. But today, Moscow’s threat to Europe’s peace is all too apparent again—and devastatingly so in Ukraine as well as in Georgia. In response, NATO should change with the strategic landscape—not with “retrenchment,” in which it builds its walls higher while Ukraine and other threatened partners burn, but with aggressive enlargement. NATO is generally considered something of a walled garden—a protected redoubt of relative peace, prosperity, and predictability. However, this reputation elides the seismic strategic revolution that founding and early expansion represented. Firmly in the nuclear age and facing Soviet expansionism after two horrific continental wars in the first half of the 20th century, the United States sought to create structures to arrest Europe’s ruinous cycles of great-power war. Against thevery real risk of Soviet imperialism and a potential third World War, NATO created a protected sanctuary around Europe’s most threatened, impoverished, and war-torn countries. “I am sure,” then-U.S. President Harry Truman said just a year before NATO’s founding, “that the determination of the free countries of Europe to protect themselves will be matched by an equal determination on our part to help them.” To create the rules-based paradise of modern Europe, the United States and its closest allies drew a line in the face of Soviet expansionism and said: No further. Despite war weariness and the steep task of reconstruction, the North Atlantic founders pooled their military power and political determination as well as risked a third World War in Europe’s defense. The countries that joined were hardly all first-rate military powers, economic dynamos, or stable democracies—manywere politically unstable, militarily sapped, and economically broken. Several, such as Portugal and Spain, were military dictatorships. The principal continental combatants in World War II—Germany, France, and Italy—were quite literally ruined by the war and took decades to recover. Yet the United States and the other original NATO members didn’t quibble interminably over the vagaries of a threatened partner’s democratic credentials or its uptake of various technical or military reforms, and they generally accepted European states that sought Washington’s protection and a Western orientation. This wasn’t because of Western indifference to democracy but rather a recognition that democratization under the shadow of an imminent Soviet threat was essentially impossible and that a country swallowed by Moscow’s imperial agenda had no chance of true self-determination—much less democracy. Speaking of NATO’s purpose, then-U.S. Secretary of State Dean Acheson described it as “designed to contribute to thestability and well-being of the member nations by removing the haunting sense of insecurity” posed by Soviet expansionism. It took time, but the strategy paid off. Under NATO and the United States’ nuclear umbrella, great-power war was avoided, Europe democratized and prospered, and the Soviet Union and its brand of colonialism was dismantled, freeing tens of millions of people. With Russia again in the throes of despotism and expansionist militarism, the conditions that accompanied NATO’s founding are all too familiar. Russian aggression in the heart of Europe is an incontrovertible reality—as Ukraine’s blood-soaked lands so clearly attest—and there is no reason to believe or expect Moscow to stop until and unless it is stopped. NATO must meet the moment. Dithering over peacetime technicalities defi es NATO’s original purpose to secure Europefrom the specter of Moscow’s violently imperial agenda. This is not a return to the Cold War, but it is no less a civilizational struggle against a military dictatorship in Moscow. This threat is particularly plain and present for the millions of Ukrainians and Georgians who have had no choice but to suffer on the wrong side of the geopolitical train tracks. NATO should return to its roots and fling open its doors to all those in Europe at risk of Russia’s predations. How can this be done? NATO decisions, including membership, require consensus. Transitioning to a wartime open door policy will require a major shift in thinking. For one, the United States, as the ultimate underwriter of NATO’s military might, should take steps to provide robust security assistance and assurances to threatened partners—such as those promises it has given Finland and Sweden until their accession is complete—and encourage other like-minded allies to do the same. Similarly, NATO handwringing over outstanding territorial disputes—almost always created or supported by Moscow—should officially become a nonissue. Russia should not be rewarded for cultivating and backing violent separatist movements that inoculate the parent countries from NATO accession. If anything, Russian meddling and aggression evinces the necessity of NATO’s protection. This is simple in principle but admittedly difficult in policy amid hot war. How can Ukraine join NATO without triggering a global conflict? First, the United States and its allies can all do more to ensure that Ukraine has military dominance overits own territory and win its war of independence. Mystifying gaps that undermine Western sanctions policies demand attention—such as continued European dependence on Russian energy, U.S. imports of Russian steel, and the growing role of China and other countries in the Middle East, Eurasia, and Asia (including friends and partners) to bypass or ease the impact of international trade sanctions. Likewise, U.S. hesitance over delivering heavy arms and munitions to Ukraine must end. The delivery of U.S. artillery and M142 High Mobility Artillery Rocket System (HIMARS) platforms have completely changed the momentum of the conflict in recent weeks; more longer-range munitions and Western fast-jet capabilities could help Ukraine expand the initiative against Russia’s high-mass but low-morale attacking force. Second, the United States could consider extending its nuclear umbrella over Ukraine to erase Russia’s nuclear advantage and any temptation it may have to use nuclear weapons as Russian conventional losses mount. Doing so would only be a stronger and clearer statement of current U.S. policy that Russia’s use of weapons of mass destruction against Ukraine would be “completely unacceptable” and “entail severe consequences,” as U.S. President Joe Biden has already said. Against such a horrifying possibility, the West could stand to be much clearer on the evident downsides of such a strategy, which would itself violate Russian nuclear doctrine. And third, the United States can and should have discussions about certain security guarantees for free areas of Ukraine, such as via the provision of the most advanced Western arms or direct Western air defense coverage. For Georgia, and even for a country like Moldova should it so choose, it is even clearer: Provide support and security guarantees over non-occupied regions. Finally, democratic principles should remain a core requirement for NATO. Although the exigencies of the moment maynot allow the luxury of waiting for perfect democratization to develop before entry, NATO can and should create more robust and independent internal mechanisms to monitor and highlight vulnerabilities, advise and assist all members with undertaking difficult reforms, and hold members accountable for sustained and significant democratic backsliding. As Ukraine’s brave people fight for survival and every inch of their homeland against Russia’s overwhelming and genocidal war, it is impossible not to wonder what might have been had NATO understood in 2008 in Bucharest or in 2014 in Wales what horrors could have been prevented if Ukraine had been spirited into the alliance, along with Georgia. Ukraine will win this war, and Russia will lose—but in many ways, it is already too late for Ukraine and Georgia, having been so thoroughly and persistently victimized by Russian aggression. Yet each moment they are left to fend for themselves only compounds the error—and the shame.