President Trump leaves the Group of Seven summit in Canada on Saturday with White House Chief of Staff John F. Kelly, left, and national security adviser John Bolton. (Sean Kilpatrick/Canadian Press/AP)
David V. Gioe is history fellow at the Army Cyber Institute and assistant professor of history at West Point. He is a U.S. Navy veteran and former Central Intelligence Agency operations officer. His opinion does not reflect any endorsement by the U.S. Department of Defense or Government.

In the wake of President Trump’s summit with North Korean leader Kim Jong Un, the threat of war still hovers in the background, albeit to a far lesser extent than it did a mere few weeks ago. Trump described the meeting as having gone “better than anybody could’ve expected,” but as recently as a few weeks ago he was reminding Kim that the U.S. military is “ready if necessary.” Nor is Korea the only site of conflict. After the United States withdrew from the Iran deal last month, national security adviser John Bolton — a new presence in the administration’s burgeoning “war cabinet” — warned that “Iran is bringing us closer to war with its belligerent activity in Iraq and Syria.”

Now, it seems, would be a good time to revisit the purpose and utility of war. If the Pentagon’s expanding budget is any indication, U.S. policymakers clearly think diplomatic problems can be solved through application of military force. Unfortunately, these perceptions of war’s utility have become unmoored from the historical record, which tells a story of chaos, devastation, unintended consequences and moral compromise. The United States would be wise to keep this in mind as it considers its next steps in a turbulent international arena. Once unleashed, the dogs of war frequently bite their masters.

At its most elemental, war is the attempt by one actor to impose its political will on another through violence. States choose war for many reasons: to secure resources or territorial possessions, to save face, restore reputation, protect allies or maintain the balance of power. Others find themselves fighting as a result of miscalculation, misinterpreted signals or when bellicose rhetoric or policy positions back leaders into a corner and war seems to be the only way out.

During the August Madness of 1914, Russian and German emperors went too far in mobilizing their armies and became prisoners of their own war plans, which eventually led to both emperors’ being toppled in the final settlement. Such inertia often presents false choices as the field of strategic vision narrows. Before World War II, Imperial Japanese militarists argued, in the words of historian Dennis Showalter, that “Japan had only one choice: between being hammer or anvil, windshield or bug.” That binary thinking pushed the country inexorably toward war.

Military leaders throughout history have professed their ability to dictate martial events. In reality, however, war events rarely unfold as the strategists intend. Just ask Napoleon on his way to Moscow in 1812, the Imperial German Army on its way to Paris via Belgium in 1914, the Japanese after Pearl Harbor, or the U.S. military after the overthrow of the Taliban in 2001 or the fall of Baghdad in 2003. States join this long list for myriad reasons: They misalign their means and their desired ends, they lose popular support, they confuse having desired goals with having a viable strategy to achieve them or they simply forget the old saw, “the enemy gets a vote.”

Indeed, countries that resort to war, particularly wars of aggression, are often sorry that they did so. After all the treasure spent and blood spilled, the result is usually worse than the status quo ante. Consider the Arabs who invaded Israel during the Six Day War of 1967 and lost ample territory, or Iraqi leader Saddam Hussein, who invaded Iran in 1980 and Kuwait in 1990, badly weakening his country both times. Why? As usual, the aggressor miscalculated the capability, resolve or alliances of its enemy.

Closer to home, although the United States outlasted (and outspent) the Soviet Union during the Cold War, it was not immune to unpopular quagmires. Vietnam looms largest, but there were other embarrassing exits — Lebanon in the early 1980s and Somalia a decade later. These events factored into Osama bin Laden’s strategic assessment of the United States as a paper tiger that would cut and run once its nose was bloodied, thus directly contributing to America’s ensuing fiascos in the Middle East and Afghanistan.

Victory in these wars has been as hard to define as to achieve, taking on different definitions in political and military contexts, a reality best embodied in George W. Bush’s premature “Mission Accomplished” declaration. Like the evolving rationales for going to war in Iraq in 2003 — Hussein supporting terrorists, gassing the Kurds, developing weapons of mass destruction and so on — notions of victory appear more modest the longer wars drag on. Meanwhile unintended consequences multiply, including shifting the balance of power from Sunni to Shiite in Iraqi politics and giving Iran additional regional influence.

To be sure, there are historical examples of war as an effective instrument for achieving a goal, such as revolutions in the United States, Algeria and Vietnam. These wars of national liberation burnish war’s allure, but they also come with the often neglected caveat that they are not wars of conquest and are fought on the winning side’s home turf. The Viet Cong and the Taliban both taught America costly lessons about home field advantage — just as the American colonists taught the British.

On occasion, wars of conquest do pan out. For instance, the United States expanded dramatically after the victory over Mexico in 1848 by successfully pioneering new tactics such as combined operations and amphibious landings. In Europe, Otto von Bismarck adroitly used three regional wars to unify Germany in 1871, but even in these successful cases of aggressive wars, the outcome was not foreordained. As Prussian General Carl von Clausewitz observed, chance and uncertainty are abiding aspects of war’s nature, irreducible beyond a certain point.

Yet even when wars are highly effective, they can also be deeply immoral. For instance, the U.S. Army was tactically and strategically effective against the American Indians during the second half of the 19th century — pursing America’s manifest destiny by expanding frontiers, securing resources, developing transportation infrastructure for white settlement and paving the way for the United States to become a key actor in the Pacific. These actions, though, were fraught with ethical compromises that remain unresolved.

Sometimes war is necessary and just. There is malevolence in the world, and at times hard steel is the only remedy. (Defeating Nazi Germany and the Confederacy come to mind.) No matter the righteousness of the cause, though, the conduct of war is a catastrophe for those touched by it, for noncombatants and soldiers alike. Winning World War II involved massive death and destruction, not least the dropping of two atomic bombs over Japan and devastating bombing in Europe.

War’s dubious utility can seldom justify this tragic human toll. After a lifetime of study, preeminent military historian John Keegan observed that war “may well be ceasing to commend itself to human beings as a desirable, or productive, let alone rational, means of reconciling their discontents.”

Given America’s massive military expenditures and technological prowess, it is understandable that Americans are hasty to apply military power. Madeleine Albright once famously asked Colin Powell what good his military was if we couldn’t use it for humanitarian intervention. Powell, as a combat veteran of a lost war, recalled that he almost “had an aneurysm” — even after the resounding success of the Persian Gulf War, Powell, a Vietnam War veteran, had a healthy respect for the gamble of resorting to armed conflict.

Would America be so bellicose as a nation if, like Powell, it had a better appreciation of war’s mixed track record? Regrettably for a country that primarily seeks international engagement through a military lens, the history of war does not reveal strategies to guarantee victory but offers sober warnings illuminated at a lamentable cost to soldiers and their societies.

Yet in all likelihood, America will remain bellicose. Like a casino, the house of war pays out just often enough to entice strategic gamblers to put their chips down, thinking this time fortune may favor them. In the increasing absence of history’s long view, one hopes that American policymakers realize the true odds of their gamble before they place their chips down on another bloody lesson for future students of military history.