I am grateful for these responses. Given space limitations, I can only respond schematically.

First, on the causes of the war. Some respondents attribute Russia’s invasion solely to Ukraine’s prospective membership in NATO; others retort that NATO was irrelevant—that the attack owed to Putin’s imperial mentality, inability to accept an independent Ukraine, and dread of its democracy, however imperfect. As I have said explicitly many times, my view has always lain between these extremes, but Kathryn Stoner sees no difference between my account and the NATO-alone-is-to blame stance. She joins those who insist that Russia had no reason whatever to fear NATO expansion, never mind the overwhelming evidence—dating back to the Yeltsin years—that it did. This view reflects our foreign policy establishment’s proclivity, which Andrew Bacevich highlights, to dismiss the possibility that other countries could justifiably see anything the United States does as threatening. Stoner and Taras Bilous are right that East Central Europe countries were eager to join the alliance, but had the idea of expanding it not taken wing in Washington, their aspirations wouldn’t have mattered. Besides, for Russian leaders, the relevant point was that NATO expanded—not why it did.

Second, regarding how the war might be ended, or end, Charles Kupchan and Jack Snyder—neither of whom justify Putin’s attack—rightly note that Ukraine, despite its best efforts and continuing Western military assistance, may fail to evict Russia from all the territories it has annexed since 2014, or even 2022. They are not alone: some in the Biden administration reportedly share this doubt. Moreover, the classified documents leaked recently by Airman Jack Teixeira reveal that Biden’s national security team is pessimistic about Ukraine’s spring counteroffensive and also expects the war in Donbas to remain stalemated through 2023. I think Kupchan and Snyder would agree that Ukraine’s desire to regain all its territories is justified—I certainly do—but they urge us to contemplate the possibility that it may not succeed. If the war drags on with no end in sight, open-ended Western military and economic support may prove unsustainable—the more so if Russia regains the momentum it lost last fall and Ukraine starts losing additional territory.

If the war drags on with no end in sight, open-ended Western military and economic support may prove unsustainable.

None of this means that Western support for Ukraine will end abruptly or even, as Snyder suggests, be pared down to prevent nuclear escalation. Still, though Kupchan argues—and he is not alone—that the United States must not be “self-deterred” by that risk, I suspect that he would agree that the possibility of escalation will influence Washington’s decisions about how and to what extent it will back Ukraine’s behalf. Secretary of State Antony Blinken’s observation that Crimea may be Russia’s “red line” is telling in this respect. Though he was not calling on Ukraine to concede Crimea, it’s evident that he envisions that Russia might resort to escalation to retain the peninsula.

Stoner regards the very thought of compromise with an aggressor as repugnant. Bilous adds, correctly, that a diplomatic settlement that concedes any Ukrainian territory to Russia would face fierce opposition on the home front—a point I make in my essay—and might also empower Ukraine’s far-right political forces. I share their aversion to cutting deals with aggressors. But the war could end on terms that fall short of Ukraine’s conception of victory on account of military circumstances (the Russian army’s resurgence) and political and economic changes in the West. One can decry this denouement and call for steps to avert it, but it cannot be ruled out simply by asserting that justice must prevail and that the West is duty-bound to back Ukraine until that happens. Oxana Shevel believes that a forced settlement (which I do not favor) would legitimize Russia’s annexations. But an armistice, which she deems preferable, could leave large amounts of Ukrainian land in Russia’s hands—and indefinitely. That’s precisely why, as Bilous notes, Ukrainians are irritated by Westerners who call for a ceasefire in the name of peace.

Ukraine might well end up retaking all the land it has lost—but, as Kupchan and Snyder note, it might not. Shevel believes that Putin’s plan to “de-Nazify” Ukraine and conquer all of Donbas will fail. But Russia could still end up holding large swathes of Ukrainian territory. In the latter case, Kyiv (above all) and its Western supporters will face difficult, unpalatable choices. That is why I have suggested ways that Ukraine might attain a substantial but less than perfect victory—something that I regard as possible. There are certainly other ways to imagine the war’s end, and of course Ukraine must decide what sacrifices, if any, it is prepared to make. Washington’s public position remains that it will support Kyiv until a complete victory is achieved, but the hard reality, which Liana Fix seems not to consider, is that it will not allow Kyiv to call all the shots because Ukraine’s decisions could have significant economic and military consequences for the United States. Fix is right that Putin shows no sign of giving up and that Ukraine and the West have little if any leverage. But that could change were Ukraine’s army to retake left-bank Kherson, the occupied parts of Zaporizhzhia, and the portion of Donetsk through which Russia’s land corridor to Crimea runs before traversing the southern parts of Zaporizhzhia and Kherson. I do not see such an outcome, or something like it, as impossible—and it may be more realistic than awaiting a post-Putin Russia.

Last, regarding a postwar Ukraine. Snyder doubts that a Ukrainian buffer state would be feasible. He recommends that the West grant Ukraine the training and weapons it needs for long-term self-defense along with economic assistance to help ready it to enter the European Union. Yet the military part of his proposal seems very similar to the buffer state concept, particularly because he opposes admitting Ukraine to NATO (on the grounds that it would provoke Russia). 

If the United States, perhaps joined by a few other allies, proves unwilling to provide Kyiv a security guarantee as a substitute, Ukraine may end up with what Snyder calls “a self-reinforcing equilibrium of power.” But the critical reinforcement part of that arrangement won’t work automatically; it depends on Russia’s future conduct toward Ukraine. Ukrainians, for obvious reasons, will be unwilling to trust Moscow to play its part in producing a lasting equilibrium. Neta Crawford is certainly right that Western assessments of Russia’s military power were overblown and that Putin’s confidence was misplaced. But her conclusion that the lesson to be learned is that “less expensive equipment of a defensive nature combined with civilian resistance tactics and civil society resilience” can foil attackers is overstated. Those weren’t the means Ukraine used to retake right-bank Kherson or Kharkiv province last fall, nor are they visible in its current fight to defend Bakhmut, Vuhledar, Avdiivka, Marinka, and other towns in Donbas. In my visits to wartime Ukraine, I have never met anyone with military experience who believes that it can defend itself against a future combined-arms assault by Russia using the strategy Crawford describes.

Though I accept the assessment of Bilous and Shevel that it won’t be possible to engage Russia so long as Putin rules, my observations pertained to the West’s long-term policy, and Shevel and I appear to agree that Russia cannot be isolated indefinitely. I reject her dismissal of engagement as an enduring, though meritless, “mantra.” The 2002 Strategic Offensive Reduction Treaty, the 2010 New START that superseded it, and Russia’s role in enabling the 2015 Joint Comprehensive Plan of Action—which averted a nuclear-armed Iran but has become defunct because President Trump withdrew from it and Biden didn’t reverse that decision—all demonstrate that engagement was fruitful even under Putin.

Michael Brenes stresses that Ukraine’s reconstruction should be supported in ways that also foster a more equitable world and tackle serious global problems, such as climate change. But I am perplexed by his claim that rather than supporting a diplomatic solution “at all costs,” progressives favor “an alternative global order”—as if the latter goal is less ambitious. Miriam Pemberton warns that Putin’s invasion may be used to justify pumped-up U.S. defense spending—a point Crawford also makes—and launching a new Cold War with China, and that festering social and economic problems at home will be denied sufficient funding as a result. Both authors identify massive, complex challenges, which of course would exist even had Putin not attacked Ukraine. They deserve serious attention, but a proper discussion of how best to address them would necessarily range far beyond the Ukraine war.