Vladimir Putin launched his war against Ukraine with expansive aims that, if achieved, would have essentially ended that country’s existence as a sovereign state. Faced with costly military setbacks, the Russian president has since defined success down, refocusing the Russian military operation on consolidating its hold in Ukraine’s east and south.

Curiously, Western aims in Ukraine have been far less clear. Almost all the debate over what to do has focused on means: on the quantity and quality of military aid to provide the country, on the wisdom of establishing a no-fly zone over Ukrainian airspace, on the extent of economic sanctions on Russia. Little has been said about what either side would have to concede in order to end the war. Also left unsaid is whether an end to the conflict would need to be formalized in a treaty signed by Russia and Ukraine or simply accepted as a reality.

Answering the question of how this war should end is vital as the struggle with Russia enters a critical moment, with a large battle looming. Wars can end when a major gap emerges between the belligerents so that one side can impose terms on the other, or when both sides realize that outright victory is not in the cards and decide it is better to settle for less than bear the costs of carrying on. In either situation, the end of the war can be codified in legal documents that address questions of territory and political and economic arrangements, or the conflict can simply wind down, coming to a de facto end without a formal peace. World War II was an example of the former; the Korean and Gulf Wars, the latter.

In principle, success from the West’s perspective can be defined as ending the war sooner rather than later, and on terms that Ukraine’s democratic government is prepared to accept. But just what are those terms? Will Ukraine seek to recover all the territory it has lost in the past two months? Will it require that Russian forces withdraw completely from the Donbas and Crimea? Will it demand the right to join the EU and NATO? Will it insist that all this be set forth in a formal document signed by Russia?

The United States, the EU, and NATO need to discuss such questions with one another and with Ukraine now. Western goals will inevitably be influenced by what happens on the ground, but what happens on the ground should not determine those goals; instead, policy aims should influence what is sought on the ground. To be sure, the Ukrainians have every right to define their war aims. But so do the United States and Europe. Although Western interests overlap with Ukraine’s, they are broader, including nuclear stability with Russia and the ability to influence the trajectory of the Iranian and North Korean nuclear programs.

It is also essential to take into account that Russia gets a vote. Although Putin initiated this war of choice, it will take more than just him to end it. He and Ukrainian President Volodymyr Zelensky will both have to consider what they require in the way of territory and terms to halt hostilities. They will also have to decide if they are prepared not only to order an end to the fighting but also to enter into and honor a peace agreement. Another complexity is that some aspects of any peace, such as the lifting of sanctions against Russia, would not be determined by Ukraine alone but would require the consent of others.

Meaningful consultations are essential if policy is not to be made carelessly and on the fly. And they are essential to preventing major fault lines from opening up between Ukraine and the United States and Europe, and even within NATO.

THREE FUTURES

It is impossible to know if the Russian military will be able to realize its ambitions of asserting greater control in the Donbas region and establishing a land bridge to Crimea—and, if it is able to, whether Putin will again revise his war aims, in this case upward. What is almost certain is that no legitimate Ukrainian government would formally accept an outcome so favorable to Russia. The atrocities that Russian forces have committed during the fight have made it far harder for Kyiv to let Moscow leave the negotiating table with anything that would seem like a reward for its brutality. Zelensky may also believe (for good reason) that allowing Russia to maintain a hold on Ukraine’s territory would make it difficult, if not impossible, for Ukraine to remain sovereign in any meaningful sense. On this score, the West should continue to provide support to Ukraine, to prevent Putin’s aggression from succeeding in Ukraine and from setting a dangerous precedent that would constitute a challenge to order everywhere. So even if Putin were prepared to cease major military operations in exchange for keeping a large swath of Ukraine, the war would probably continue at some level, much as it has in the so-called frozen conflict in the Donbas since 2014.

One alternative to a scenario favoring Russia would be a stalemate. Things would stand more or less where they did before the invasion, with Russia occupying Crimea and exercising de facto control through its proxies over parts of the Donbas. Such a future would come about if Ukraine clawed back some of what Russia has gained over the past two months but if neither Ukraine nor Russia were able to achieve decisive military progress. This outcome could be acceptable to Ukraine, which has a powerful incentive to end a war that has caused so much death and destruction. It would be peace at a price, but potentially a price worth paying. And in principle, Putin, too, might support such an outcome, judging that there was little to gain from continuing the fight. If, as part of this scenario, Ukraine agreed not to join NATO, he might also calculate he could persuade many Russians that the country had won the war, even if it didn’t acquire much territory. If such a consensus emerged, it would be one worth supporting.

But it seems overly optimistic to imagine that a military stalemate would pave the way for a diplomatic settlement. Putin would be hard-pressed to make a plausible case that such a muddied result justified the military, diplomatic, and economic costs of his war. Moreover, given his past rhetoric, he seems unlikely to sign away all claims to Ukraine, accepting its permanent separation from Russia and letting it choose a liberal, Western-oriented path for itself, including membership in the EU. The near certainty that such an outcome would not result in major sanctions relief, an end to war crimes investigations, or calls for reparations also argues against Putin accepting this scenario. A stalemate would almost certainly become an open-ended conflict. And again, many in Ukraine would reject any arrangement that left Russia in control of any Ukrainian territory.

A third future would be defined by Ukrainian military success. Russia would be forced to accept not merely the pre-2022 status quo but the pre-2014 status quo. In theory, this would be an ideal outcome for Ukraine, which would regain all the sovereignty it has lost in the past eight years, and for international order, as it would reinforce the norm that territory must not be acquired by force. In practice, however, things would be more complicated. Even if Ukraine succeeded in ousting Russian troops, the country would still be vulnerable to missile and artillery attacks emanating from Russia, to say nothing of cyberattacks and political interference. Even more important, it is near impossible to imagine Putin accepting such an outcome, since it would surely threaten his political survival, and possibly even his physical survival. In desperation, he might try to widen the war through cyberattacks or attacks on one or more NATO countries. He might even resort to chemical or nuclear weapons. It is far from certain that Russia has the mechanisms in place to prevent Putin from ordering such escalation if he decided he had nothing to lose.

The potential for Russian escalation raises the question of whether at this point it would be wise for Ukraine to attempt to take back all of the Donbas and Crimea. Arguably, these aims are better left for a postconflict, or even a post-Putin, period in which the West could condition sanctions relief on Russia’s signing of a formal peace agreement. Such a pact might allow Ukraine to enjoy formal ties to the EU and security guarantees, even as it remained officially neutral and outside NATO. Russia, for its part, might agree to withdraw its forces from the entirety of the Donbas in exchange for international protections for the ethnic Russians living there. Crimea might gain some special status, with Moscow and Kyiv agreeing that its final status would be determined down the road.

HISTORY’S ADVICE

As the United States contemplates its strategy for Ukraine, it is useful to keep in mind two lessons of the Cold War. The first was to avoid direct armed conflict with the Soviet Union unless vital U.S. interests were threatened. The second was to accept less than optimal outcomes so as to avoid threatening vital Soviet interests, something that could all too easily lead to war. This recognition that there were limits to the United States’ goals meant deciding not to roll back Soviet advances in Eastern Europe after Moscow crushed the 1956 revolution in Hungary and the 1968 revolution in Czechoslovakia. It meant stopping Israeli forces from decimating the Egyptian Third Army after they surrounded it near Cairo during the 1973 war between the Soviet-allied Arab states and the U.S.-allied Israel. And it meant accepting communist rule in the Soviet Union itself. Such restraint was articulated in the doctrine of containment as developed by the diplomat George Kennan. But over time, as Kennan suggested, the successful application of containment could add to pressures that would undermine communism—as it eventually did, after four decades.

The first lesson of the Cold War is reflected in existing Western policy toward Ukraine. From the outset of the crisis, the United States made it clear that it would not place boots on the ground or establish a no-fly zone, since doing so could bring U.S. and Russian forces into direct contact and raise the risk of escalation. Instead, Washington and its NATO partners opted for an indirect strategy of providing arms, intelligence, and training to Ukraine while pressuring Russia with economic sanctions and diplomatic isolation.

As for the second lesson, the United States’ and NATO’s decision to pursue their aims through limited means has worked to a considerable extent. That choice has not prevented Russia from destroying Ukraine’s civilian centers, but the battle between the armed forces of the two countries has favored Ukraine. The question now is whether the West should embrace limited ends, eschewing military efforts to oust Russia from all of Ukraine or demanding regime change in Moscow as a condition of stopping the war.

Whatever goals the West ultimately settles on, requiring that the war end with a formal peace agreement should not be one of them. The problem is not that it is impossible to come up with a plausible formula for mutual compromise that leaves each side better off; it is that depending on the formula, one or both sides might judge that they are better off continuing a war that holds out the possibility of a better outcome than they would be signing a pact that rules it out. With both countries still eyeing the possibility of military gains and wanting to avoid appearing weak, a formal pact appears out of reach for the foreseeable future.

All this points to a long war. It will likely be fought mostly in Ukraine’s east and south, although Russia would retain the ability to attack other targets. The elements of a strategy for a long-term, open-ended war are well known: provide Ukraine with the weapons, ammunition, training, and intelligence it needs to defend itself against Russia; make sure that NATO remains strong enough to discourage Russia from escalating the conflict or preventing supplies from reaching Ukraine; reduce energy imports from Russia as much as possible and as soon as possible.

The conclusion is clear: the United States and its NATO partners should consult with one another and with Ukraine over the aims of the war. The United States and NATO also need to refine their plans for deterring and responding to any Russian attacks on other countries or any Russian use of weapons of mass destruction. In the near term, Western success will be highly unlikely to involve a peace treaty, a true end to the conflict, or regime change in Russia. Instead, success for now could consist of a winding down of hostilities, with Russia possessing no more territory than it held before the recent invasion and continuing to refrain from using weapons of mass destruction. Over time, the West could employ a mix of sanctions and diplomacy in an effort to achieve a full Russian military withdrawal from Ukraine. Such success would be far from perfect, just preferable to the alternatives.