In June, Ukraine’s most powerful backers met at the G7 summit before attending Ukraine’s peace conference in Switzerland, which hosted representatives from nearly eighty countries. For one week, they met to discuss Volodymyr Zelensky’s ten-point peace plan, announced a plan to fund Ukraine using frozen Russian assets, and introduced a U.S.-Ukraine bilateral security agreement. As the United States and its allies are working to put Ukraine in the best position possible for eventual ceasefire negotiations, what should their top priority be? 

Ukrainian officials claim the war will end either with Russia’s total defeat or the inevitable destruction of their homeland. Western commentators frequently echo this claim, creating a false dichotomy between Ukraine routing Russia or accepting conquest and vassaldom. 

Framed this way, the only endings are either unrealistic or unacceptable. The destruction of Ukraine would not only be a tragedy but also a severe blow to the international norms against territorial conquest, NATO’s cohesion, and U.S. credibility. Ukraine, meanwhile, is unlikely to eject Russia entirely; the country is stretched thin just defending the territory it currently holds. 

Our team of researchers at the Harvard Kennedy School’s Belfer Center examined eight major conflicts from World War II to the present for insights into the outcomes of interstate wars that share key attributes with the Russia-Ukraine War. In most cases, a war ends with both combatant governments intact—neither complete victory nor total defeat for either party. A unifying feature of any exception to this rule is the direct intervention of the United States. However, President Joe Biden has made clear that the United States is unwilling to “fight World War III in Ukraine.” 

Ukraine’s most vital interest is the preservation of its sovereignty: an independent government chosen by the people of Ukraine. Any peace agreement that does not preserve a sovereign Ukraine in the long term is a failure. However, sovereignty is not binary, and a deal to protect this vital interest is about understanding relative risk. In assessing possible endgames for Ukraine, policymakers should ask a simple question: does this help or hurt Ukraine’s chances of preserving its sovereignty in the long term?  

History shows that what won’t protect Ukraine’s sovereignty is a bare-bones ceasefire that only achieves what Secretary of State Blinken described as a “Potemkin Peace.” The First Nagorno-Karabakh War ended with an inconclusive ceasefire that allowed Azerbaijan to rebuild and retool for an offensive to take the contested region almost thirty years later. Similarly, the Minsk Agreements froze the war in eastern Ukraine for a few years. Still, the parties had weak incentives to uphold the deal, allowing Russia to invade again in 2022. 

The lesson to draw from these case studies is simple. Agreements that established material conditions that were difficult for military force to change and rendered both parties invested in the settlement terms were more likely to establish a sustainable peace. 

The top priority for Ukraine and its allies should be achieving terms that minimize risks to Ukraine’s sovereignty by creating a durable, sustainable peace: long-term military aid and multilateral security guarantees, Ukrainian military neutrality, and a rebuilding effort alongside economic integration with the West.

First, long-term military aid offers the best protection for Ukrainian sovereignty. Western aid and training after the 2014 invasion were enough to prepare Ukraine to deliver a shocking failure to Russia in its 2022 assault on Kyiv. After the Korean War, the United States assisted the South in building a world-class military and created a military balance that has kept the peace for seventy-five years. While the United States won’t station 30,000 troops in Ukraine as it has in South Korea, the Korean War’s aftermath shows that military strength can dissuade even a dedicated opponent.

The United States and its European allies should enshrine consistent aid to Ukraine in domestic legislation. The bilateral security deals Ukraine has negotiated with at least thirteen countries, including the recent one with the United States and the European Union’s (EU) multi-year Ukraine aid fund, are steps in the right direction. The United States should also fund Ukraine through annual appropriations, such as Foreign Military Financing and longer-term funds like the EU’s. More regularized funding at a lower “peacetime level” will also reduce domestic political disputes. Finally, the West should offer Ukraine security guarantees that are stronger than the “assurances” offered in the Budapest Memorandum. As part of that, the United States could commit to surge aid in the event of renewed Russian aggression. The United States’s existing agreement is a framework that can be built upon for a more robust set of protections.

Second, Ukraine should reinstate its former neutrality. For their part, Western leaders should publicly recognize Ukraine’s neutral stance. Slow progress toward NATO membership, described as Putin’s “brightest of all red lines” by CIA Director Bill Burns, likely has more risk than benefit for Ukrainian sovereignty. In the Cambodia-Vietnam conflict, an essential element of the settlement was Cambodian neutrality, assuaging Chinese and Vietnamese fears of an alignment against them. However, like Finland during the Cold War, military neutrality should be an armed, alert, and self-sufficient status.  

Third, Ukraine must be rebuilt. Economic prosperity will harden Ukraine against further incursions and, therefore, protect Ukrainian sovereignty post-war. Consider Finland, which maintained its sovereignty at the end of the Continuation War against the Soviet Union, although at the cost of 11 percent of its territory. Today, Finland is prosperous and democratic. Ukraine currently controls most of its major metropolitan areas and maintains access to the Black Sea, where it has resumed agricultural shipping at near pre-war levels. The fundamental ingredients to rebuilding a thriving, prosperous society are still present. A robust economy will not only enable Ukraine to build a domestic defense industry and fund a strong military but also ensure that peace is sustainable for the Ukrainian people. This will be a major reconstruction effort, potentially financed in part through investment proceeds generated from frozen Russian assets. Ukraine should also begin integrating with Western Europe, leading to eventual EU membership. While the Allies’ unconditional World War II victory is an implausible model for Ukraine, more applicable is the Allies’ creation of a new security architecture and the U.S. Marshall Plan. These ensured that, unlike after the “Carthaginian” settlement of Versailles in 1919, peace would last.  

While Ukraine need not relinquish its claims to territory that is rightfully theirs, insisting that all territory be returned before any negotiations, as Zelensky has, will likely detract from opportunities to cement its sovereignty. Given the choice to prioritize territorial concessions or multilateral security guarantees in peace negotiations, Ukraine would be best served by making itself as strong and steady as possible. 

As Ukraine and its Western allies formulate a strategy to end the war, leaders should remember what matters most in Ukraine: sovereignty. The key will be designing a peace that is not only resilient against future Russian aggression but also sustainable for the Ukrainian people. We hope that leaders in both the United States and Ukraine, armed with the knowledge of how past wars ended, can succeed in ensuring Ukraine remains sovereign and prosperous for decades to come.

 Kate Davidson, Raphael J. Piliero, and Peter Gaber are researchers with the Applied History Project at the Harvard Kennedy School’s Belfer Center for Science and International Affairs. They are also the authors of a recently released research paper on the history of conflict resolution and its implications for the Russia-Ukraine War.

Follow Kate Davidson on LinkedIn.

Follow Raphael J. Piliero on LinkedIn and X @RaphaelPiliero.

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