For an alternate viewpoint, see “Counterpoint: This Is Not the Time for NATO Expansion. 

A genuinely realistic assessment of the NATO expansion process of the previous decades was that it did not go far enough, was not militarily serious enough, and that, while offering Moscow the opportunity and aid in becoming a pillar of the liberal West, the alliance was prepared to return to the containment policies of the Cold War. Russia, not NATO, was on trial, and, as Ronald Reagan might have said: the alliance was prepared to “trust but verify.”

Vladimir Putin is now exacting a particularly Russian kind of price for the West’s failure to bring in Ukraine and Georgia into NATO. And while additional forces have begun to flow toward the new “Eastern Front,” these are late to arrive, too few in number, widely dispersed, lack sufficient combat power or logistics infrastructure, and consume an unsustainable proportion of shrunken American and allied militaries. Perhaps even more important, with the rise of a revisionist China and the trauma of lost wars in the greater Middle East, the United States has developed a kind of strategic tunnel vision, increasingly unable to see its global role.

In addition, the mechanisms of the Atlantic alliance have become dangerously rusty and perhaps corrupted. In his powerful pitch to the Congress, Ukraine president Volodymyr Zelensky bruited the idea of a sort of “League of the Geopolitical West,” for the defense of at-risk, front-line states like Ukraine or Taiwan. Zelensky rightly noted that Japan, for example, is liberal and Western in ways that some current NATO members may not be. Russian subversion and Chinese “Belt-and-Road” debt-trap diplomacy may have crippled NATO as an instrument of containment.

While current sympathy for Ukraine’s plight is in the news, a geopolitical Realism and the impulse to blame the West first have become too deeply rooted in current political discourse to expect the Ukraine shame to change such minds for long. There has been quiet conversations about how to halt this conflict by creating an “off-ramp” for Putin that would allow him to be able to declare mission accomplished and end the worst of the slaughter. Even if the first principle of any such deal is likely to force Kyiv to give up its desire to join the institutional West and the Atlantic alliance.

Still, the brutality of the Russian campaign in Ukraine has, at least for the moment, muffled the claims of “national conservatives,” political science “Realists” and populist demagogues of the Tucker Carlson variety that Putin’s invasion was a response to NATO enlargement, an attempt to re-establish a legitimate “sphere of influence” or “strategic depth.” Even Donald Trump has dialed down his bromance with the “genius” of Moscow.

John Mearsheimer of the University of Chicago offers perhaps the clearest demonstration of why the argument against NATO expansion is flawed. Writing in Foreign Affairs in the immediate aftermath of the Russian invasion of Crimea in 2014, his rendering of the “liberal illusions that provoked Putin” to annex the peninsula, seize Georgia’s districts that border Russia in 2008, and support separatist proxies in the Donbas and the Moldovan region of Transnistria, are explained as Putin simply defending Russia against the sort of aggression from the West that Moscow had suffered before from “Napoleonic France, imperial Germany and Nazi Germany.” Recently, Mearsheimer doubled down on his 2014 analysis, arguing that Western politicians are now “inventing this story that … Putin is interested in creating a greater Russia.”

Not even Putin’s own declarations that Ukraine was an “inalienable part” of Russia’s “spiritual space” can counter the Realist conviction that the attack is just the working of a simple bloodless national interest. Neither does the constant striving of Ukrainians, against great odds, to fight the Russians and their proxies. The Ukrainians who are the central actors in this drama, cannot realistically be regarded as puppets of the West.

Regardless of political beliefs and NATO’s flaws, the Ukraine war makes plain that Putin is building a new Iron Curtain across Eastern Europe. It is critical for the United States, for the peace of Europe and the durability of geopolitical liberalism that this curtain stands as far east as possible, and that the West initiate a strategy to undermine its foundations and eventually to tear it down. This is an epoch-defining challenge to the NATO alliance, a second bite of the post-Cold-War apple. It is likewise a moment that will define the United States as a genuinely global power.