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Why Wars Are Easy to Start and Hard to End

Misperception, sunk costs, escalation, and internationalization all make conflicts last longer than planned.

Walt-Steve-foreign-policy-columnist20
Walt-Steve-foreign-policy-columnist20
Stephen M. Walt
By , a columnist at Foreign Policy and the Robert and Renée Belfer professor of international relations at Harvard University.
Ukrainian fighters and weapons in Donetsk
Ukrainian fighters and weapons in Donetsk
Ukrainian gunners prepare to fire with a self-propelled rocket launcher near a front line in the Donetsk region, Ukraine, on Aug. 27. ANATOLII STEPANOV/AFP via Getty Images

I’ve written several columns on important foreign-policy ideas that national leaders forget at their peril, such as the balance of power, nationalism, and the security dilemma. This week, I’m offering up another one, a simple observation that every world leader or foreign-policy advisor ought to have prominently displayed on their desk, on their office wall, or maybe just tattooed on the inside of their eyelids so they don’t ever, ever forget it: “It’s much easier to start a war than to end it.”

Illustrations of this phenomenon are ubiquitous. As Geoffrey Blainey described in his classic book The Causes of War, many past conflicts were fueled by “dreams and delusions of a coming war,” and especially the belief that it would be quick, it would be cheap, and it would yield a decisive victory. In 1792, for example, the armies of Austria-Hungary, Prussia, and France all rushed to the battlefield believing the war would be resolved after a battle or two. The French radicals thought their recent revolution would quickly spread to others, and the opposing monarchies believed the revolutionary armies were an incompetent rabble that their professional soldiers would easily sweep aside. What they got instead was nearly a quarter-century of recurring warfare that dragged in all the major powers and spread around the globe.

Similarly, in August 1914, the nations of Europe marched off to war saying the soldiers would be home by Christmas, blissfully unaware that the anticipated Christmas homecoming wouldn’t take place until 1918. Iraqi leader Saddam Hussein succumbed to much the same illusion in 1980, believing that the 1979 revolution had left Iran vulnerable to an Iraqi attack. The resulting war lasted eight years, and the two states suffered hundreds of thousands of deaths and vast economic damage before calling it quits.

I’ve written several columns on important foreign-policy ideas that national leaders forget at their peril, such as the balance of power, nationalism, and the security dilemma. This week, I’m offering up another one, a simple observation that every world leader or foreign-policy advisor ought to have prominently displayed on their desk, on their office wall, or maybe just tattooed on the inside of their eyelids so they don’t ever, ever forget it: “It’s much easier to start a war than to end it.”

Illustrations of this phenomenon are ubiquitous. As Geoffrey Blainey described in his classic book The Causes of War, many past conflicts were fueled by “dreams and delusions of a coming war,” and especially the belief that it would be quick, it would be cheap, and it would yield a decisive victory. In 1792, for example, the armies of Austria-Hungary, Prussia, and France all rushed to the battlefield believing the war would be resolved after a battle or two. The French radicals thought their recent revolution would quickly spread to others, and the opposing monarchies believed the revolutionary armies were an incompetent rabble that their professional soldiers would easily sweep aside. What they got instead was nearly a quarter-century of recurring warfare that dragged in all the major powers and spread around the globe.

Similarly, in August 1914, the nations of Europe marched off to war saying the soldiers would be home by Christmas, blissfully unaware that the anticipated Christmas homecoming wouldn’t take place until 1918. Iraqi leader Saddam Hussein succumbed to much the same illusion in 1980, believing that the 1979 revolution had left Iran vulnerable to an Iraqi attack. The resulting war lasted eight years, and the two states suffered hundreds of thousands of deaths and vast economic damage before calling it quits.

Even highly successful military campaigns often lead not to quick victories but to interminable quagmires. The 1967 Six-Day War lasted less than a week, but it resolved none of the underlying political issues between Israel and its neighbors and merely set the stage for the more costly War of Attrition (1969-1970) and the October War in 1973. Israel’s invasion of Lebanon in 1982 was a near-total success militarily, but the resulting occupation of southern Lebanon lasted 18 years, cost hundreds of lives, led to the creation of Hezbollah, and laid the groundwork for several even more costly clashes. One would be hard-pressed to find a more successful military operation than Operation Desert Storm in 1991, but Saddam managed to cling to power after his army was ousted from Kuwait, and the United States ended up patrolling no-fly zones over Iraq and conducting occasional aerial attacks for another decade.

The United States’ initial successes in Afghanistan in 2001 and Iraq in 2003 proved to be wholly illusory. Instead of “Mission Accomplished,” as then-U.S. President George W. Bush infamously proclaimed prematurely aboard an aircraft carrier less than two months after invading Iraq, in both cases what lay ahead was a costly and ultimately unsuccessful war against surprisingly resilient and effective insurgencies. Saudi Arabia’s Mohammed bin Salman should have pondered that experience before launching his own ill-advised war against the Houthis in Yemen.

Vladimir Putin of Russia is the latest world leader who started a war believing victory would come quickly and easily. Whatever one believes about the ultimate origins and responsibility for the war in Ukraine, there is no question that Russia started the fighting. Putin seems to have believed that his initial war aims would not take long to achieve or cost that much, either because he exaggerated Russia’s strengths, underestimated Ukrainian resolve, miscalculated how third parties would react, or some combination of all three. He is now learning the same painful lesson that so many other world leaders have discovered: It is far easier to start a war than to end one.

But why do we see so few short, decisive wars that live up to their initiator’s expectations and turn out to be easy to bring to a halt? It is not enough to recognize that war is always uncertain, that prewar estimates are frequently flawed, or that fighting often produces unintended consequences that render prewar calculations irrelevant. What leaders contemplating war need to appreciate are the powerful tendencies that make wars get bigger, cost more, and last longer than they expect.


First, it is impossible to know in advance how fiercely an opponent will resist, and leaders contemplating an attack are likely to underestimate it. Failure to appreciate the power of nationalism is one reason for this tendency, and the related tendency to see one’s own nation as innately superior to all potential foes encourages aggressors to discount an opponent’s ability to resist. Nobody starts a war if they recognize their opponent is stronger, is more united, and cares more about the outcome; the remarkable part is how often a state starting a war gets this wrong.

Second, once a war is underway, the familiar problem of sunk costs invariably kicks in. Once the adversaries suffer losses, their leaders will want to achieve sufficient gains to justify the sacrifices that have already been made. Families who have lost loved ones will not want to be told that those sacrifices were in vain. Military commanders may have warned about the risks of war or opposed the initial decision beforehand, but they will not want to shoulder the blame for a defeat and will press for every chance to deliver victory. Letting sunk costs determine current policy may be irrational, but that doesn’t mean it doesn’t happen. The desire to recoup sunk costs also encourages each side’s war aims to expand, as they try to obtain benefits commensurate with the mounting losses.

Third, wars continue because the act of fighting itself hardens each side’s image of the other. No matter how suspicious or hostile the warring parties were at the onset, those feelings of hatred and suspicion will only increase as each inflicts more death, destruction, and suffering on the other. A desire for vengeance is only natural under these circumstances, which in turn fuels the desire for decisive victory over an increasingly despised and hated enemy.

Fourth, as the image of the enemy hardens, the ability to negotiate declines. Diplomatic ties may be severed, making direct communication more difficult, and anyone who dares raise the possibility of compromise is likely to be denounced as a traitor (or worse). Even if negotiations do begin, neither side will trust the other enough to cut a deal. Peace settlements typically face serious commitment problems (i.e., “How can I be sure my opponent won’t rearm, break the peace treaty, and come after me again?”), and that obstacle will be more and more pronounced as each side’s image of the other worsens.

In the case of Ukraine, for example, the Volodymyr Zelensky government has every reason not to trust Putin or his associates, and at this point Putin and his advisors don’t trust anyone either. Unfortunately, Russia’s ambassador to the United Nations in Geneva, Gennady Gatilov, was probably correct when he said last week that “the more the conflict goes on, the more difficult it will be to have a diplomatic solution.”

Fifth, wars also have a powerful tendency to escalate and widen. If one side is losing, it may consider using more force, striking at new and more dangerous targets, or raising the stakes in other ways. The recent explosions in Crimea, the dangerous situation at the Zaporizhzhia nuclear power plant, and the car bombing in Moscow of a pro-Putin commentator show exactly how this process can work, no matter who is ultimately responsible for these actions.

Wars also expand because outside parties jump in to prop up one side, as NATO has done for Ukraine since the beginning of the war, or to make gains for themselves while others are distracted. The Syrian civil war is a perfect example: What began as a domestic uprising inside Syria eventually triggered direct or indirect military interventions by Russia, Turkey, Iran, Saudi Arabia, the United States, Israel, and several others. Unfortunately, the more other countries get involved and have a stake in the outcome of a conflict, the harder it is to get all of them to agree to end it.

A sixth problem that prolongs wars is the deteriorating quality of information. As the saying sometimes attributed to former U.S. Sen. Hiram Johnson goes, “The first casualty when war comes is truth.” Although countries at war should think and act as coolly and clearly as possible, wartime conditions make this harder to do.

Governments have powerful incentives to sustain public morale by trumpeting good news, concealing setbacks, and constantly reminding the population of the enemy’s evil nature. They impose censorship and suppress or marginalize dissenters, making it hard even for those on the inside to get an accurate picture of what is really happening on the battlefield. Dictatorships have many ways to control what the public knows, but this problem is hardly unknown in democracies, where media organizations often succumb to patriotic fervor or deliberate government manipulation.

If both elites and publics in all the warring parties believe the war is going well for their side, there won’t be much pressure to bring it to a close. They can’t all be right, of course, but it may take a long time before the real situation is widely understood. As British Prime Minister David Lloyd George remarked in 1917, “If people really knew [about conditions at the front], the war would be stopped tomorrow. But of course they don’t know and can’t know.”

There’s one final problem: The people who started a war have little incentive to end it before achieving something they can portray as a victory, because settling for less is an admission that they screwed up big time. In his fascinating book Every War Must End, the late Fred C. Iklé (who was no dove), pointed out that bringing a war to a close often requires bringing in new leaders, because the people who chose to go to war are often unwilling or unable to admit they were wrong. This is disheartening news, because removing those responsible is always difficult, is sometimes impossible, and may not occur before many more lives are lost.

All wars do come to an end eventually, of course, but that is cold comfort when the costs far outweigh the benefits. The lesson is clear enough: Although wars may sometimes be necessary, they should be entered into with the greatest reluctance and only under direst necessity. Those charged with making such decisions must never forget that going to war unleashes powerful political and social forces that are hard to anticipate or control. Once you unleash the dogs of war, there’s no telling who will end up getting bit. It is a safe bet, however, that it will take a lot longer and cost a lot more than you think.

Stephen M. Walt is a columnist at Foreign Policy and the Robert and Renée Belfer professor of international relations at Harvard University.

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