In 1988, the military historian James Stokesbury observed that democracies are best at fighting either little wars, which are reserved for “professionals” and don’t involve ordinary citizens, or really big wars that mobilize all of society. Those democracies, he continued, have “very real problems trying to fight a middle-sized war, where some go and some stay home.”

Middle-sized wars are big enough to cause immense destruction and bloodshed but small enough that they do not engage the full home front. They should not be confused with what the military theorist Carl von Clausewitz called a limited war, in which the goal may be only to hurt the enemy, not to destroy it. A limited war is by design, whereas a middle-sized war grows out of what was intended to be strictly a small war. Generals and political leaders know what they are doing in a limited war. U.S. leaders in today’s middle-sized wars do not.

It may be uncomfortable to consider the so-called forever wars in the Middle East—which have killed or wounded tens of thousands of U.S. soldiers and left countless dead on all sides—as merely middle-sized. But Stokesbury’s point is one of comparison. The wars in Afghanistan and Iraq, as well as those in Korea and Vietnam, as gruesome as they were, cannot be equated to the two big world wars of the twentieth century. Nor can they be grouped with little wars, such as the invasion of Grenada in 1983 and of Panama in 1989, which made headlines for a few days but were essentially imperial policing actions. U.S. military interventions in Bosnia in 1995 and Kosovo in 1999 also had exceedingly few American casualties and were mainly air operations conducted within strict limits.

For the United States, middle-sized wars present a unique problem. They ruin presidential administrations along with the American public’s regard for the U.S. government’s ability to conduct foreign policy. It would seem that the American people are finished with middle-sized wars and never want to repeat them. In fact, after each of the United States’ recent middle-sized wars, the public and politicians alike declared an end to them. This was especially true after the wars in Vietnam and Iraq, which destroyed the reputations of top policymakers. Yet the United States may be on the brink of another. The Trump administration’s war in Iran has the potential to evolve into a middle-sized war if the clerical regime does not surrender, as U.S. President Donald Trump demands, and continued U.S. and Israeli bombing leads to anarchy in Iran and destabilizes the Persian Gulf. The gap between toppling an existing order and erecting a new, more pliable one can be vast.

The United States exists in the world as a de facto empire, and misbegotten wars are embedded in the history of imperialism itself. The point of imperialism is to involve the empire in places that are potentially beneficial but not necessarily vital to its national interest. Repeated involvement in periodic middle-sized wars, even as public officials and civilians alike declare they will never happen again, reflects the modern imperial condition of the United States. If leaders are not careful, these middle-sized wars will weaken the United States and contribute to its ultimate demise.

DANGEROUS MISCALCULATIONS

In a crisis-prone world, a great power such as the United States cannot simply hide, keep a low profile, or always expect others to take action. After the invasion of Iraq, some analysts made a distinction between wars of choice and wars of necessity. But such a distinction goes only so far. Although the dichotomy certainly helps, it is not a cure-all. A war can appear to be one of necessity until it fails; then, it is looked back on as a war of choice. As Clausewitz wrote, “War is the province of uncertainty; three-fourths of the things on which action in war is based lie hidden in the fog of a greater or less[er] uncertainty.” A president often lacks complete information about the ground-level reality half a world away, but he still has to make a binary choice of whether to go to war—a choice for which he will be judged later by people with the advantage of historical hindsight.

Making decisions under these circumstances risks fundamental miscalculation. It may be widely agreed that radical actors and theocrats with nuclear weapons are dangerous, but choosing when to take military action against them is less straightforward. The Iraq war proved the folly of acting too precipitously. Although the Iranian regime is much closer to achieving nuclear capabilities in 2026 than Iraqi leader Saddam Hussein was in 2003, it’s not clear whether that progress necessitated the risk of a middle-sized war, as the Trump administration has made a possibility.

Tensions with China and Taiwan illustrate the challenge of decision-making in scenarios in which miscalculation is both likely and dangerous. The western Pacific is of greater consequence to U.S. interests than are Ukraine and the Middle East. The forever wars in the Middle East, by and large, have had only a limited effect on financial markets, and those markets have priced in the region’s geopolitical turmoil over recent decades. It would be a much different story if there were ever outright warfare in the western Pacific, home to the world’s most vital shipping lanes, supply chains, and economies. To the average American, a Pacific war, if not calibrated perfectly, could dwarf the scale of miscalculation and tragedy in the wars in Afghanistan, Iraq, and Vietnam, primarily because of the economic impact but also because of the destruction of vital materials, such as semiconductors. Yet the planning for such a conflict goes on in both Beijing and Washington, increasing the likelihood that it might one day happen. Getting into a war over Taiwan and the South China Sea, perhaps even a middle-sized war, is easy. Ending such a war is harder. How that end comes, and what it might look like, ranges from anarchy and the end of communist rule in China to a military truce born of exhaustion following the collapse of world stock markets. Despite all the neat war games about a short, sharp conflict over Taiwan, real wars have a way of turning into all-encompassing realities of their own.

Conflict with North Korea, too, could one day evolve into a middle-sized war. The country has no dependable social organizations because no elements of civil society exist there, so any conflict that threatens to bring down the regime also threatens to unleash domestic chaos. This chaos would likely be succeeded by calls for an international intervention (specifically, by the United States), perhaps even democracy building, and the surviving remnants of North Korean leader Kim Jung Un’s security forces could wind up battling each other in a civil war in which other global powers might have no good options when it comes to choosing sides.

Trump promised to end forever wars. But through loose rhetoric, poor planning, a lack of policy discipline, and the normal collection of mistakes and miscalculations that any individual leader makes in a volatile world, he has found himself blundering into new ones. His administration has not included significant numbers of ground troops in its vast air and sea armada deployed against Iran. But the slippery slope of incrementalism poses a problem. If a civil war, or something akin to it, breaks out in Iran, the administration may feel compelled to send special forces and advisers to aid one side. And the risks of escalation spiral from there. The war in Vietnam took years to evolve into a middle-sized war, spanning the entire Kennedy administration and the beginning of the Johnson administration. The situation in Iran might follow a similar trajectory.

Iran is not the only conflict that could spiral out of control on Trump’s watch. The administration also risks a war with the drug cartels in Mexico, which Trump has officially designated as terrorist organizations. A military conflict with the cartels would have all the makings of an irregular, grinding, middle-sized war in which locating enemies would be difficult, and permanently defeating them would be nearly impossible. The Trump administration’s military action to remove President Nicolás Maduro in Venezuela and its missile strikes in Nigeria, too, are further examples of conflicts with domestic considerations that are as ambiguous and unpredictable as Iraq’s were in 2003. A post-Maduro Venezuela could eventually transform itself into a well-functioning democracy, but it also might descend into anarchy. In Nigeria, the Trump administration seems not to realize that internal attacks on Christians are part of a slow, complex unraveling of the Nigerian state itself, especially in the hinterlands, which has the potential to escalate into broader warfare.

A danger sign that a small war or military action might expand into a middle-sized war is when there is too much talk about geopolitics and not enough about local cultural and political conditions. The historian Barbara Tuchman has argued that the United States would have done much better in Vietnam if it had thought less geopolitically and more locally. The biggest U.S. foreign policy fiascos happened because policymakers were obsessed with regional and global consequences they often could not properly manage, and thus ignored critical conditions on the ground. In Vietnam, U.S. leaders overlooked the history and nature of Vietnamese nationalism; in Iraq, it was sectarianism. Tuchman has encouraged leaders to trust area specialists more than grand strategists or democracy promoters. Sophisticated and specific cultural knowledge, she has observed, is much more useful than metrics and shadowy schemes.

Middle-sized wars often stem from misunderstandings about the place intervention is meant to help. The key, then, is for the intervening country to know what it is getting itself into. This may seem easy, but it can be the hardest part of policymaking. Bringing up cultural matters and differences is tricky because it can easily be misconstrued as prejudice, which pushes people to avoid critical conversations about realities on the ground. But it is such discussions that can keep a superpower out of trouble. The U.S. State Department’s China hands warned about a communist takeover on the Chinese mainland years before it happened, in 1949. The failure to accept that reality and deal early on with the communist regime, as cruel as it was, played a role in later U.S. efforts to contain communism in both Korea and Vietnam. And Middle East experts in the State Department familiar with local culture and conditions warned against U.S. military involvement in Iraq in 2003.

Lurking always in these cases is the danger of false honor—the impulse to react violently to injured pride—which powers great and small have been prone to do since the dawn of history. The Greek historian Thucydides famously identified honor as a cause for conflict between states. In a world as violent and tumultuous as today’s, states’ honor will sometimes be offended—by hostage-taking, for instance, or the siege of an embassy in a war-torn country. In these situations, leaders are often tempted to intervene with force. Trump has a dangerous tendency to react to personal insults, which could lead to military overreaction.

Escalatory, emotional rhetoric can propel small wars into becoming middle-sized ones. In March 2004, for example, four U.S. private contractors were killed, burned, and hung from a bridge in Fallujah in western Iraq. Fallujah had developed a reputation for being especially hostile to the U.S. military occupation, and Marine officers recommended that the town be cordoned off because there was no tactical need to capture or administer it. But senior officials in the U.S. Army and the George W. Bush administration believed that Fallujah had to be taught a lesson because American honor had been slighted. The subsequent conquest of the town resulted in dozens of Marine casualties and led to many more in a second battle the following November. The unfolding of events in Fallujah proves that the greater the power, the more it has to discipline itself. Avoiding small and even middle-sized wars starts with this kind of restraint.

Land engagements are especially dangerous because they can quickly become quagmires. In all his military actions thus far—Nigeria, Venezuela, Iran—Trump has used air and naval assets almost exclusively. That is a good thing. The United States should be especially wary of land engagements in the Eastern Hemisphere, where all of its middle-sized wars have been fought since World War II. This isn’t only because of the challenges posed by the great distances involved; it is also because the quality of U.S. intelligence has generally been weaker there than in the United States’ own backyard (although even there, the United States might get into unnecessary trouble). Former U.S. Secretary of Defense Donald Rumsfeld envisioned Iraq as another Panama—in and out in a matter of weeks or months, and using only a limited number of troops. But U.S. intelligence on Panama was infinitely greater than that on Iraq, and Iraq is a much bigger country. Rumsfeld and the George W. Bush administration failed to heed Tuchman’s advice and trust the area experts who warned against involvement. They also lacked an adequate and realistic plan for Iraq after an invasion. What resulted was a costly middle-sized war. Every U.S. military action, no matter how small, should be accompanied by a fully fledged day-after plan that is constantly updated, which will further integrate area expertise from the professional bureaucracy into foreign policy decision-making.

During his time as chairman of the Joint Chiefs of Staff in the early post–Cold War era, Colin Powell, who later served as U.S. Secretary of State, argued that the United States should not commit to a war unless it has overwhelming force, an exit strategy, a vital national interest, a clear objective, and broad support. This idea, which became known as the Powell Doctrine, has been sidelined in recent years. Yet it remains relevant. Perhaps the ultimate objective of the Powell Doctrine was not to avoid defeat, per se, but to avoid middle-sized wars. And for great powers such as the United States, avoiding middle-sized wars means being very careful about the small wars it gets involved in.

The empires and great powers that have survived longest are those that have avoided middle-sized wars. The Byzantine Empire, for instance, lasted over a thousand years by doing everything possible to avoid open warfare. As the United States celebrates its 250th year, it also faces a series of escalating conflicts. If it cannot avoid the middle-sized wars that have plagued it in the past, there may be a fatal split between the public and its governing elite. The effects are unlikely to be immediate, but such divisions are how republics slowly die.

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