More than forty years ago, I wrote a book titled Negotiating Peace that analyzed the diplomatic and military dynamics of bringing a war to an end. It drew material from the endings of wars through nearly two centuries, as well as a closer examination of a few major cases that had extended periods of simultaneous combat and negotiations. It also drew on theoretical work, chiefly by economists, about bargaining. Parts of the book got rather technical—it included differential equations—but it also had a more digestible prescriptive side. An appendix titled “Lessons for the Statesman at War” included forty-four pieces of advice for how best to employ diplomatic and military instruments to achieve a peace that will maximize the interests of one’s own nation.

Much of this advice is at least potentially applicable to the current war in Ukraine—from the standpoint not only of decisionmakers in Kyiv and Moscow but also of policymakers in Washington, in terms of what they should expect or hope to promote. The actual applicability of some of my apothegms will depend on events yet to unfold, but the following outlines a few of the major lessons.

The ending of the war in Ukraine will almost certainly entail some form of bargaining between Ukraine and Russia, and will leave a situation that represents a compromise between the interests of the two nations. It is rare in interstate conflicts for one belligerent to eradicate the other so that it has no need for any bargaining or compromise. It is not so rare in intrastate warfare, in which an insurgency might eliminate and replace an incumbent regime or the regime might crush the insurgency solely through military means (such as Sri Lanka’s final eradication of the Tamil Tiger insurgency in 2009).

But the eradication of a nation-state is a different matter and a less feasible outcome. Iraqi ruler Saddam Hussein managed to do that temporarily when he used armed force to swallow Kuwait in 1990, but a U.S.-led intervention reversed that outcome the following year. The objective of Russian president Vladimir Putin in launching the current war in February 2022 may have been to eliminate Ukraine as an independent country, either through formal incorporation into Russia or by installing a puppet regime in Kyiv. It now is clear that Russian military force is insufficient to achieve any such outcome. And obviously, Ukraine cannot eliminate the Russian state.

Even a war that is said to end in a surrender does not involve totally imposing the will of one side on the other and involves a negotiated compromise. No surrender is unconditional if the side surrendering still has some ability to fight. The surrender of Japan in 1945 was a deal in which Japan agreed to stop fighting and thus spared the Allies what would have been an extremely costly military conquest of the main islands of Japan. 

Another possible ending of an interstate war is for one or both belligerents simply to withdraw from the battle (as occurred with the border war between China and India in 1962), leaving a frozen conflict with or without occupation of the disputed territory. Such an outcome is possible in Ukraine, but an explicit war-ending agreement has multiple advantages for all concerned. It provides a framework that facilitates prisoner exchanges, peacekeeping protocols, and other useful measures. It provides a degree of certainty that reduces the risk of misinterpretations of the other side’s actions leading to renewed warfare. 

In any event, bargaining, possibly tacit, is still taking place even without a formal written agreement. The withdrawal from battle leaves a state of affairs that affects the interests of each belligerent in both positive and negative ways, and which each side must compare with the “no agreement” situation of continued warfare to decide whether to accept the bargain that this state of affairs represents.

An implication of the foregoing is that to speak of the termination of the war in Ukraine in terms of “winning” or “losing” the war is not helpful in understanding likely scenarios for termination and in preparing for those scenarios.

The end of the war is likely to be preceded by a period of bargaining—perhaps in formal negotiations—accompanied by continued combat, rather than a military outcome being fully established before work begins on constructing a political outcome. Traditionally there tended to be a temporal separation between military operations and peace diplomacy—such as with the end of World War I, when the guns were silenced by an armistice at Compiègne in November 1918 and a peace treaty was negotiated at Versailles the following year. But that sequence was mainly a legacy of the limitations of pre-modern communications, when day-to-day coordination of military operations and diplomacy was difficult (except for someone like Napoleon Bonaparte, who combined military field command and ultimate political authority in his own person). That difficulty no longer exists, and belligerents have an incentive to continue using their military instrument in ways that they hope will add heft to their diplomacy.

Regardless, silencing the guns—and ending the suffering of Ukrainians from a continued war, and with it the threat of escalation into a wider war—ought to be considered the most important component of terminating this war. Moreover, even an agreement that is labeled as merely an armistice and not a full resolution of political issues may be the only peace agreement that a conflict ever gets. That has been true, for seventy years and counting, of the armistice agreement that ended the Korean War. This is one of the reasons that the Korean War—which was one of the major cases I studied in researching the book—has been mentioned by some other observers as a model for terminating the war in Ukraine.

Belligerents will become willing to negotiate a peace agreement when they both have demonstrated, to themselves and to the enemy, the limits of what they are able and willing to do militarily, and there is little or no prospect for either side to change the situation on the battlefield appreciably with one more offensive effort. Another analyst, I. William Zartman, has called such a situation a “hurting stalemate.”

A war that has not reached a stalemate and is going either too badly or too well for a belligerent is likely to lead that belligerent to resist peace negotiations for the time being, for different reasons. Too badly, and the impulse is to keep fighting to shore up the situation on the battlefield, in the hope of looking and being stronger in whatever negotiations eventually take place. Too well, and the tendency is to expand one’s war objectives and to hope to accomplish them without the need for negotiation and compromise. The first year of the Korean War illustrated each of these tendencies, as the front line moved up and down the peninsula with the initial North Korean invasion, the U.S.-led intervention under the United Nations flag, the later Chinese intervention, and another UN push that finally brought the line to what became a stalemate near the 38th parallel.

An implication of this pattern for the war in Ukraine is that it is a mistake to talk about hoped-for breakthroughs by the Ukrainian counteroffensive, with Russian forces thrown backward, as being a precursor, and maybe even a necessary precursor, for peace negotiations. Given Putin’s stake in the conflict, his reaction might be just like the U.S. reaction to the two major communist offensives that threw friendly forces backward in Korea: to see this as making it all the more necessary to assume increased military costs and risks to improve the battlefield map before sitting down to talk peace.

One other lesson, regarding the substance of any possible peace agreement, is already worth mentioning. Notwithstanding the value of a written peace agreement in lending precision and certainty to the postwar situation, sometimes some uncertainty can have value in helping the parties come to any agreement at all. This was true regarding the uncertain future of the South Vietnamese government in the years following the peace agreement between the United States and North Vietnam in 1973. Although the concept of a “decent interval” involved a domestic political motive for President Richard Nixon, leaving the fate of the Saigon regime somewhat to chance was a way to reconcile the United States’ refusal to explicitly abandon that regime with Hanoi’s objective to rule all of Vietnam.

In Ukraine, the bargaining gap that must be bridged is between Ukraine’s disinclination to formally cede any of its territory and Putin’s need to show some gain from his costly military misadventure. Some political issues probably will have to be in effect punted, with their eventual outcome uncertain, if any peace agreement is to be reached, despite the future risk of misunderstandings and festering grievances. Mechanisms such as referenda that leave some future outcomes to chance may be part of a formula for ending this war.  

Paul Pillar retired in 2005 from a twenty-eight-year career in the U.S. intelligence community, in which his last position was as a National Intelligence Officer for the Near East and South Asia. Earlier he served in a variety of analytical and managerial positions, including as chief of analytic units at the CIA covering portions of the Near East, the Persian Gulf, and South Asia. Professor Pillar also served in the National Intelligence Council as one of the original members of its Analytic Group. He is also a contributing editor for this publication.