Fifteen months of fighting has made clear that neither side has the capacity—even with external help—to achieve a decisive military victory over the other. Regardless of how much territory Ukrainian forces can liberate, Russia will maintain the capability to pose a permanent threat to Ukraine. The Ukrainian military will also have the capacity to hold at risk any areas of the country occupied by Russian forces—and to impose costs on military and civilian targets within Russia itself. These factors could lead to a devastating, years-long conflict that does not produce a definitive outcome.
By Samuel Charap FOR FOREIGN AFFAIRS
Russia’s invasion of Ukraine in February 2022 was a moment of clarity for the United States and its allies. An urgent mission was before them: to assist Ukraine as it countered Russian aggression and to punish Moscow for its transgressions. While the Western response was clear from the start, the objective—the endgame of this war—has been nebulous.
This ambiguity has been more a feature than a bug of U.S. policy. As National Security Adviser Jake Sullivan put it in June 2022, “We have in fact refrained from laying out what we see as an endgame. . . . We have been focused on what we can do today, tomorrow, next week to strengthen the Ukrainians’ hand to the maximum extent possible, first on the battlefield and then ultimately at the negotiating table.” This approach made sense in the initial months of the conflict. The trajectory of the war was far from clear at that point. Ukrainian President Volodymyr Zelensky was still talking about his readiness to meet his Russian counterpart, Vladimir Putin, and the West had yet to supply Kyiv with sophisticated ground-based rocket systems, let alone tanks and long-range missiles as it does today. Plus, it will always be difficult for the United States to speak about its view on the objective of a war that its forces are not fighting. The Ukrainians are the ones dying for their country, so they ultimately get to decide when to stop—regardless of what Washington might want.
But it is now time that the United States develop a vision for how the war ends. Fifteen months of fighting has made clear that neither side has the capacity—even with external help—to achieve a decisive military victory over the other. Regardless of how much territory Ukrainian forces can liberate, Russia will maintain the capability to pose a permanent threat to Ukraine. The Ukrainian military will also have the capacity to hold at risk any areas of the country occupied by Russian forces—and to impose costs on military and civilian targets within Russia itself.
These factors could lead to a devastating, years-long conflict that does not produce a definitive outcome. The United States and its allies thus face a choice about their future strategy. They could begin to try to steer the war toward a negotiated end in the coming months. Or they could do so years from now. If they decide to wait, the fundamentals of the conflict will likely be the same, but the costs of the war—human, financial, and otherwise—will have multiplied. An effective strategy for what has become the most consequential international crisis in at least a generation therefore requires the United States and its allies to shift their focus and start facilitating an endgame.
WHAT WINNING DOESN’T LOOK LIKE
As of the end of May, the Ukrainian military was on the verge of conducting a significant counteroffensive. After Kyiv’s successes in two earlier operations in the fall of 2022, and given the generally unpredictable nature of this conflict, it is certainly possible that the counteroffensive will produce meaningful gains.
Western policymakers’ attention is primarily devoted to delivering the military hardware, intelligence, and training necessary to make that happen. With so much seemingly in flux on the battlefield, some might argue that now is not the time for the West to start discussions on the endgame. After all, the task of giving the Ukrainians a chance at a successful offensive campaign is already straining the resources of Western governments. But even if it goes well, a counteroffensive will not produce a militarily decisive outcome. Indeed, even major movement of the frontline will not necessarily end the conflict.
More broadly, interstate wars generally do not end when one side’s forces are pushed beyond a certain point on the map. In other words, territorial conquest—or reconquest—is not in itself a form of war termination. The same will likely be true in Ukraine: even if Kyiv were successful beyond all expectations and forced Russian troops to retreat across the international border, Moscow would not necessarily stop fighting. But few in the West expect that outcome at any point, let alone in the near term. Instead, the optimistic expectation for the coming months is that the Ukrainians will make some gains in the south, perhaps retaking parts of the Zaporizhzhia and Kherson regions, or push back the Russian assault in the east.
Those potential gains would be important, and they are certainly desirable. Fewer Ukrainians would be subjected to the unspeakable horrors of Russian occupation. Kyiv might retake control of major economic assets, such as the Zaporizhzhia Nuclear Power Plant, the largest in Europe. And Russia would have suffered another blow to its military capabilities and global prestige, further raising the costs of what has been a strategic catastrophe for Moscow.
The hope in Western capitals is that Kyiv’s gains on the battlefield will then force Putin to the negotiating table. And it is possible that another tactical setback would diminish Moscow’s optimism about continued fighting. But just as losing territorial control does not equate to losing a war, neither does it necessarily induce political concessions. Putin could announce another round of mobilization, intensify his bombing campaign on Ukraine’s cities, or merely hold the line, convinced that time will work for him and against Ukraine. He might well continue fighting even if he thinks he will lose. Other states have chosen to keep fighting despite recognizing the inevitability of defeat: think, for example, of Germany in World War I. In short, gains on the battlefield will not in themselves necessarily bring about an end to the war.
After over a year of fighting, the likely direction of this war is coming into focus. The location of the frontline is an important piece of that puzzle, but it is far from the most important one. Instead, the key aspects of this conflict are twofold: the persistent threat that both sides will pose to each other, and the unsettled dispute over the areas of Ukraine that Russia has claimed to annex. These are likely to remain fixed for many years to come.
Ukraine has built an impressive fighting force with tens of billions of dollars’ worth of aid, extensive training, and intelligence support from the West. The Ukrainian armed forces will be able to hold at risk any areas under Russian occupation. Further, Kyiv will maintain the capability to strike Russia itself, as it has demonstrated consistently over the past year.
Of course, the Russian military will also have the capacity to threaten Ukrainian security. Although its armed forces have suffered significant casualties and equipment losses that will take years to recover from, they are still formidable. And as they demonstrate daily, even in their current sorry state, they can cause significant death and destruction for Ukrainian military forces and civilians alike. The campaign to destroy Ukraine’s power grid might have fizzled, but Moscow will maintain the ability to hit Ukraine’s cities at any time using airpower, land-based assets, and sea-launched weapons.
In other words, no matter where the frontline is, Russia and Ukraine will have the capabilities to pose a permanent threat to each other. But the evidence of the past year suggests that neither has or will have the capacity to achieve a decisive victory—assuming, of course, that Russia does not resort to weapons of mass destruction (and even that might not secure victory). In early 2022, when its forces were in far better shape, Russia could not take control of Kyiv or oust the democratically elected Ukrainian government. At this stage, the Russian military even appears unable to take all the areas of Ukraine that Moscow claims as its own. Last November, the Ukrainians forced the Russians to retreat to the east bank of the Dnieper River in the Kherson region. Today, the Russian military is in no state to push back across the river to seize the rest of the Kherson and Zaporizhzhia regions. Its attempt in January to push north on the plains of the Donetsk region near Vuhledar—a far less taxing offensive than a river crossing—ended in a bloodbath for the Russians.
The Ukrainian military, meanwhile, has defied expectations and may well continue to do so. But there are significant impediments to achieving further progress on the ground. Russian forces are heavily dug in on the most likely axis of advance in the south. Open-source satellite images show they have created multilayered physical defenses—new trenches, antivehicle barriers, obstacles and revetments for equipment and materiel—across the frontline that will prove challenging to breach. The mobilization Putin announced last fall has ameliorated the manpower problems that had earlier allowed Ukraine to advance in the Kharkiv region, where Russia’s thinly defended lines were vulnerable to a surprise attack. And the Ukrainian military is largely untested in offensive campaigns that require integrating various capabilities. It has also suffered significant losses during the war, most recently in the battle for Bakhmut, a small city in the Donetsk region. Kyiv is also facing shortages of critical munitions, including for artillery and air defenses, and the hodgepodge of Western equipment it received has strained maintenance and training resources.
These limitations on both sides strongly suggest that neither one will achieve its stated territorial objectives by military means in the coming months or even years. For Ukraine, the objective is extremely clear: Kyiv wants control over all its internationally recognized territory, which includes Crimea and the parts of the Donbas that Russia has occupied since 2014. Russia’s position is not quite as categorical since Moscow has maintained ambiguity about the location of the borders of two of the five Ukrainian regions it claims to have annexed: Zaporizhzhia and Kherson. Regardless of this ambiguity, the bottom line is that neither Ukraine nor Russia will likely establish control over what they consider their own territory. (This is not to suggest that both parties’ claims should be accorded equal legitimacy. But the manifest illegitimacy of the Russian position does not appear to deter Moscow from holding it.) Put differently, the war will end without a resolution to the territorial dispute. Either Russia or Ukraine, or, more likely, both, will have to settle for a de facto line of control that neither recognizes as an international border.
A FOREVER WAR BEGINS
These largely immutable factors could well produce a drawn-out hot war between Russia and Ukraine. Indeed, history suggests that is the most likely outcome. A study from the Center for Strategic and International Studies, using data from 1946 to 2021 compiled by Uppsala University, found that 26 percent of interstate wars end in less than a month and another 25 percent within a year. But the study also found that “when interstate wars last longer than a year, they extend to over a decade on average.” Even those that last fewer than ten years can be exceptionally destructive. The Iran-Iraq war, for example, lasted for nearly eight years, from 1980 to 1988, and resulted in almost half a million combat fatalities and roughly as many wounded. After all its sacrifices, Ukraine deserves to avoid such a fate.
A long war between Russia and Ukraine will also be highly problematic for the United States and its allies, as a recent RAND study I co-authored with the political scientist Miranda Priebe shows. A protracted conflict would keep the risk of possible escalation—either to Russian nuclear use or to a Russian-NATO war—at its current elevated level. Ukraine would be on near-total economic and military life support from the West, which will eventually cause budgetary challenges for Western countries and readiness problems for their militaries. The global economic fallout of the war, including the volatility in grain and energy prices, would persist. The United States would be unable to focus its resources on other priorities, and Russian dependence on China would deepen. Although a long war would also further weaken Russia, that benefit does not outweigh these costs.
While Western governments should continue to do all they can to help Ukraine prepare for the counteroffensive, they also need to adopt a strategy for war termination—a vision for an endgame that is plausible under these far-from-ideal circumstances. Because a decisive military victory is highly unlikely, certain endgames are no longer plausible. Given the persistence of fundamental differences between Moscow and Kyiv on core issues such as borders, as well as intense grievances after so many casualties and civilian deaths, a peace treaty or comprehensive political settlement that normalizes relations between Russia and Ukraine seems impossible, too. The two countries will be enemies long after the hot war ends.
For Western governments and Kyiv, ending the war without any negotiations might seem preferable to talking to the representatives of a government that committed an unprovoked act of aggression and horrific war crimes. But interstate wars that have reached this level of intensity do not tend to simply peter out without negotiations. If the war persists, it will also be extremely difficult to transform it back into a low-intensity localized conflict like the one that took place in the Donbas from 2014 to 2022. During that period, the war had a relatively minimal impact on life outside the conflict zone in Ukraine. The sheer length of the current frontline (over 600 miles), the strikes on cities and other targets far beyond the line, and the mobilization underway in both countries (partial in Russia, total in Ukraine) will have systemic—perhaps even near-existential—effects on the two belligerents. For example, it is difficult to imagine how the Ukrainian economy can recover if its airspace remains closed, its ports remain largely blockaded, its cities under fire, its men of working age fighting at the front, and millions of refugees unwilling to return to the country. We are past the point when the impact of this war can be confined to a particular geography.
Since talks will be needed but a settlement is out of the question, the most plausible ending is an armistice agreement. An armistice—essentially a durable cease-fire agreement that does not bridge political divides—would end the hot war between Russia and Ukraine but not their broader conflict. The archetypal case is the 1953 Korean armistice, which dealt exclusively with the mechanics of maintaining a cease-fire and left all political issues off the table. Although North and South Korea are still technically at war, and both claim the entirety of the peninsula as their sovereign territory, the armistice has largely held. Such an unsatisfactory outcome is the most likely way this war will end.
In contrast with the Korean case, the United States and its allies are not doing the fighting in Ukraine. Decisions in Kyiv and Moscow will ultimately be far more determinative than those made in Berlin, Brussels, or Washington. Even if they wanted to do so, Western governments could not dictate terms to Ukraine—or to Russia. Yet even while acknowledging that Kyiv will ultimately make its own decisions, the United States and its allies, in close consultation with Ukraine, can begin to discuss and put forward their vision for the endgame. To some extent, they have already been doing so for months: U.S. President Joe Biden’s May 2022 op-ed in The New York Times made clear that his administration sees this war ending at the negotiating table. His senior officials have regularly repeated this view ever since, although the language of helping Ukraine for “as long as it takes” often garners more attention. But Washington has steadfastly avoided providing any further details. Moreover, there do not appear to be any ongoing efforts either within the U.S. government or among Washington, its allies, and Kyiv to think through the practicalities and substance of eventual negotiations. Compared with the efforts to provide resources for the counteroffensive, practically nothing is being done to shape what comes next. The Biden administration should begin to fill that gap.
THE COSTS OF WAITING
Taking steps to get diplomacy off the ground need not affect efforts to assist Ukraine militarily or to impose costs on Russia. Historically, fighting and talking at the same time has been a common practice in wars. During the Korean War, some of the most intense fighting took place during the two years of armistice talks, when 45 percent of U.S. casualties were incurred. Beginning to plan for the inevitable diplomacy can and should occur in parallel with the other existing elements of U.S. policy—as well as with the ongoing war.
In the short term, that means both continuing to help Kyiv with the counteroffensive and beginning parallel discussions with allies and Ukraine about the endgame. In principle, opening a negotiation track with Russia should complement, not contradict, the push on the battlefield. If Ukraine’s gains make the Kremlin more willing to compromise, the only way to know that would be through a functioning diplomatic channel. Setting up such a channel should not cause either Ukraine or its Western partners to let up the pressure on Russia. An effective strategy will require both coercion and diplomacy. One cannot come at the expense of the other.
And waiting to set the stage for negotiations has its costs. The longer the allies and Ukraine go without developing a diplomatic strategy, the harder it will be to do so. As the months go by, the political price of taking the first step will go up. Already, any move that the United States and its allies make to open the diplomatic track—even with Ukraine’s support—would have to be delicately managed lest it be portrayed as a policy reversal or an abandonment of Western support for Kyiv.
Fighting and talking at the same time has been a common practice in wars.
Starting preparations now makes sense also because conflict diplomacy will not yield results overnight. Indeed, it will take weeks or perhaps months to get the allies and Ukraine on the same page about a negotiating strategy—and even longer to come to an agreement with Russia when the talks begin. In the case of the Korean armistice, 575 meetings were required over two years to finalize the nearly 40 pages of the agreement. In other words, even if a negotiation platform were set up tomorrow, months would elapse before the guns fell silent (if the talks were to succeed, which is far from a given).
Devising measures to make the cease-fire stick will be a thorny but critical task, and Washington should ensure that it is ready to assist Kyiv in that effort. Serious work should begin now on how to avoid what Ukrainian officials, including Zelensky, describe derisively as “Minsk 3,” a reference to the two failed cease-fire deals that were brokered with Russia in the Belarusian capital in 2014 and 2015, after its earlier invasions. These agreements failed to durably end the violence and included no effective mechanisms for ensuring the parties’ compliance.
Using data from conflicts between 1946 and 1997, the political scientist Virginia Page Fortna has shown that strong agreements that arrange for demilitarized zones, third-party guarantees, peacekeeping, or joint commissions for dispute resolution and contain specific (versus vague) language produced more lasting cease-fires. These mechanisms reinforce the principles of reciprocity and deterrence that allow sworn enemies to achieve peace without resolving their fundamental differences. Because these mechanisms will be challenging to adapt to the Ukraine war, governments need to work on developing them now.
Although an armistice to end this war would be a bilateral agreement, the United States and its allies can and should assist Ukraine in its negotiating strategy. In addition, they should consider what measures they can take in parallel to provide incentives for the parties to get to the table and minimize the chances that any cease-fire collapses. As Fortna’s research suggests, security commitments to Ukraine—some assurance that Kyiv will not face Russia alone if Moscow attacks again—should be part of this equation. Too often, the discussion of security commitments is reduced to the question of NATO membership for Ukraine. As a member, Ukraine would benefit from Article 5 of NATO’s founding treaty, which requires members to consider an armed attack against one of them as an attack against them all. But NATO membership is more than just Article 5. From Moscow’s perspective, membership in the alliance would transform Ukraine into a staging ground for the United States to deploy its own forces and capabilities. So even if there were consensus among allies to offer Kyiv membership (and there is not), granting Ukraine a security guarantee through NATO membership might well make peace so unattractive to Russia that Putin would decide to keep fighting.
Squaring this circle will be challenging and politically fraught. One potential model is the U.S.-Israel 1975 memorandum of understanding, which was one of the key preconditions for Israel to agree to peace with Egypt. The document states that in light of the “long-standing U.S. commitment to the survival and security of Israel, the United States Government will view with particular gravity threats to Israel’s security or sovereignty by a world power.” It goes on to say that in the event of such a threat, the U.S. government will consult with Israel “with respect to what support, diplomatic or otherwise, or assistance it can lend to Israel in accordance with its constitutional practices.” The document also explicitly promises “remedial action by the United States” if Egypt violates the cease-fire. This is not an explicit commitment to treat an attack on Israel as an attack on the United States, but it comes close.
A similar assurance to Ukraine would give Kyiv an enhanced sense of security, encourage private-sector investment in Ukraine’s economy, and enhance deterrence of future Russian aggression. Whereas today Moscow knows for sure that the United States will not intervene militarily if it attacks Ukraine, this kind of statement would make the Kremlin think more than twice—but it would not raise the prospect of new U.S. bases on Russia’s borders. Of course, Washington would need confidence in the durability of the cease-fire so that the probability of the commitment being tested would remain low. Avoiding war with Russia should remain a priority.
When the time comes, Ukraine will need other incentives such as reconstruction aid, measures of accountability for Russia, and sustained military assistance in peacetime to help Kyiv create a credible deterrent. In addition, the United States and its allies should supplement the coercive pressure being applied to Russia with efforts to make peace a more attractive option, such as conditional sanctions relief—with snapback clauses for noncompliance—that could prompt compromise. The West should also be open to a dialogue on broader European security issues so as to minimize the chance of a similar crisis with Russia breaking out in the future.
The first step toward making this vision a reality over the coming months is to stand up an effort in the U.S. government to develop the diplomatic track. An entire new U.S. military command element, the Security Assistance Group–Ukraine, has been devoted to the aid and training mission, which is led by a three-star general with a staff of 300. Yet there is not a single official in the U.S. government whose full-time job is conflict diplomacy. Biden should appoint one, perhaps a special presidential envoy who can engage beyond ministries of foreign affairs, which have been sidelined in this crisis in nearly all relevant capitals. Next, the United States should begin informal discussions with Ukraine and among allies in the G-7 and NATO about the endgame.
In parallel, the United States should consider establishing a regular channel of communication regarding the war that includes Ukraine, U.S. allies, and Russia. This channel would not initially be aimed at achieving a cease-fire. Instead, it would allow participants to interact continually, instead of in one-off encounters, akin to the contact group model used during the Balkan wars, when an informal grouping of representatives from key states and international institutions met regularly. Such discussions should begin out of the public eye, as did initial U.S. contacts with Iran on the nuclear deal, signed in 2015.
These efforts might well fail to lead to an agreement. The odds of success are slim—and even if negotiations did produce a deal, no one would leave fully satisfied. The Korean armistice was certainly not seen as a triumph of U.S. foreign policy at the time it was signed: after all, the American public had grown accustomed to absolute victories, not bloody wars without clear resolution. But in the nearly 70 years since, there has not been another outbreak of war on the peninsula. Meanwhile, South Korea emerged from the devastation of the 1950s to become an economic powerhouse and eventually a thriving democracy. A postwar Ukraine that is similarly prosperous and democratic with a strong Western commitment to its security would represent a genuine strategic victory.
An endgame premised on an armistice would leave Ukraine—at least temporarily—without all its territory. But the country would have the opportunity to recover economically, and the death and destruction would end. It would remain locked in a conflict with Russia over the areas occupied by Moscow, but that conflict would play out in the political, cultural, and economic domains, where, with Western support, Ukraine would have advantages. The successful reunification of Germany, in 1990, another country divided by terms of peace, demonstrates that focusing on nonmilitary elements of the contestation can produce results. Meanwhile, a Russian-Ukrainian armistice would also not end the West’s confrontation with Russia, but the risks of a direct military clash would decrease dramatically, and the global consequences of the war would be mitigated.
Many commentators will continue to insist that this war must be decided only on the battlefield. But that view discounts how the war’s structural realities are unlikely to change even if the frontline shifts, an outcome that itself is far from guaranteed. The United States and its allies should be capable of helping Ukraine simultaneously on the battlefield and at the negotiating table. Now is the time to start.