Since the end of World War II, the American military has been described so often by defense analysts, military historians, and U.S. presidents as the most lethal armed force in history that it’s become a cliché. During the Cold War, Moscow claimed with some validity to have military capabilities on a par with the United States. But since the demise of the Soviet Union and America’s crushing victory over Saddam Hussein in the Gulf War of 1990-1991, no serious student of military affairs of whom I’m aware disputes the reality of American military supremacy.

The most capable military in history is also by far and away the most expensive. The United States will spend at least $650 billion on defense this fiscal year, which is more than the next seven nations’ spending combined.

All of this begs an awkward but important question: Why can’t the most lethal military establishment in history win its wars?

The military’s scorecard since the world-changing victory in 1945 has been, in a word, underwhelming. In Korea, an ill-prepared American army was almost driven off the peninsula in its first few months of combat in 1950. Ultimately, the American-led U.N. army did oust communist forces from South Korea, but it was driven to the brink of defeat (again!) before it did so. In November 1950, the Chinese People’s Army entered the fray and drove the U.N. army out of North Korea, frustrating its goal of unifying the two Koreas under a pro-Western government.

After assuming the burden of the fighting from the South Vietnamese in 1965, the U.S. military found itself bogged down in a long, bloody, and indecisive war against the North Vietnamese regular army and Vietcong guerrillas. After eight years of inconclusive fighting, the United States had dropped more bombs on Vietnam than it did on Germany and Japan in World War II. The Communists, however, wouldn’t give up. The Americans withdrew, leaving the South Vietnamese to certain defeat at the hands of their communist adversaries.

In the Lebanese civil war of the early ’80s, American forces were withdrawn soon after a Jihadist terrorist set off a truck bomb, blowing up a Marine barracks and killing 241 U.S. Marines.

The lightning-fast victory in the Gulf War of 1990-1991 resurrected the U.S. military’s prestige from the ashes of Vietnam and ushered in an entirely new way of war. As the strategist Andrew Marshall put it soon after victory, “the information dimension has become central to the outcome [of modern conflicts]… Long-range precision strike weapons coupled with systems of sensors and a command and control system will come to dominate much of warfare.”

“ Early and dramatic success in the wars in Afghanistan and Iraq was soon followed by year after year of frustrating, inconclusive operations and political setbacks. ”

Yet many historians today view the Gulf War not as the great victory it appeared to be in 1991 but rather as the first campaign in a long, ultimately unwinnable civil war in Iraq that has never truly ended.

In the wake of the Gulf War, a new foreign policy consensus emerged. America, said Madeleine Albright, Bill Clinton’s secretary of state, was the “world’s indispensable nation,” with both a right and an obligation to enforce the rules-based international order and take out bad guys. Between 1990 and 1997, the military was deployed on more than 30 operations of bewildering variety—peacekeeping, peace enforcement, humanitarian relief, and traditional combat missions. Most of these deployments came up short of their objectives.

The most infamous was the effort to stabilize the failing state of Somalia. That led to an undeclared war between Somali warlord Mohamed Aidid and U.S. forces, culminating in the Battle of Mogadishu. Eighteen American soldiers were killed in furious combat; American corpses were dragged through the angry streets. Soon after the battle, President Clinton withdrew all American forces from Somalia.

Then came 9/11 and the global War on Terror.

Early and dramatic success in the wars in Afghanistan and Iraq was soon followed by year after year of frustrating, inconclusive operations and political setbacks. The Taliban today is stronger than it was when American forces first deployed to Afghanistan in 2001. When Obama withdrew American forces from Iraq in December 2011, the country was awash in sectarian violence, and any hope of establishing a pro-Western, democratic regime there had vanished. Iraq was a war, writes journalist George Packer, “conceived in deceit and born in hubris, a historic folly that took the American eye off Al Qaeda and the Taliban, while shattering Iraq into a million bloody pieces.”

What explains this unenviable record of achievement?

Some analysts locate the problem within the military’s culture. Most of America’s opponents in operations since World War II, and particularly since the end of the Cold War, have been non-state actors and insurgents highly skilled and resourceful in taking on conventional military forces in “asymmetrical warfare.” American forces have been trained, organized and indoctrinated in conventional operations using high-tech weaponry, so they have been fighting with a considerable handicap.

Certainly, this issue was in play during Vietnam, and in the Iraq War, when the Army found itself out of its depth in confronting a complex insurgency after seizing Baghdad with relative ease. The United States military hasn’t done well with counterinsurgency, which always involves political as well as military conflict, and it would do well to stay clear of them in the future. Firepower, mass, maneuver, and advanced technologies—the sine qua non of the American way of war—are not effective weapons against lightly armed insurgents.

Other students of recent American wars see hubris as a major factor in explaining military failure. Policymakers and generals alike have consistently underestimated their enemies, particularly their staying power. As the political scientist Dominic Tierney quipped, “We have the power. They have the willpower.”

Yet, according to an increasingly influential chorus of foreign relations scholars and historians such as Andrew J. Bacevich, Barry Posen, and Stephen Walt, the fundamental problem lies not in the military itself, but in the realm of American politics and grand strategy. One administration after another has engaged in imperial overreach, trying to reshape societies and entire regions of the world about which, despite the vast intelligence assets they command, they remain fundamentally ignorant.

After the catastrophe in Vietnam, the military and the foreign policy establishment were determined to stay clear of foreign entanglements where America’s vital interests were not clearly at stake. According to the Weinberger Doctrine—named for Ronald Reagan’s secretary of state, Caspar Weinberger—the U.S. military should only be deployed when policymakers could define clear and attainable objectives, and only as a last resort.

As these scholars see it, the Weinberger doctrine went into sharp decline after the Gulf War and vanished into thin air with the arrival of the global War on Terror. Since the early ’90s, one president after another, Republican and Democrat, has pursued an overly militarized foreign policy agenda, deploying forces instead of seeking solutions through the country’s other instruments of influence: diplomacy, soft power, and economic incentives.

This new creed of military interventionism began in the aftermath of the “stunning” victory in the Gulf War. It was hubristic and idealistic at the same time, and drew on a tradition of American exceptionalism as old as Puritan John Winthrop’s “City upon a Hill” sermon of 1630. Americans were a unique people, with a special role to play in world affairs.

A cadre of prominent neoconservatives, spearheaded by Robert Kagan, Charles Krauthammer, and William Kristol, spread the gospel of U.S. military intervention as a kind of panacea for all sorts of international problems and crises. “Military strength alone will not avail," counseled Kagan, “if we do not use it actively to maintain a world which both supports and rests on American hegemony.”

“ The Trump administration is carrying out more military operations than its predecessor, against a wider array of adversaries, with looser rules of engagement. ”

Just after victory in the Persian Gulf in March 1991, a very wise MIT foreign relations expert named Barry Posen had cautioned foreign policy decision-makers, “Don’t get the idea it will always be this easy. The terrain was favorable to our high-tech weapons, and we were up against a second-rate gangster. We must not confuse what we did here with using military power to redirect the domestic politics of a society.”

Posen’s warning fell on deaf ears in Washington.

Even presidents who’ve promised to act with restraint in foreign affairs have fallen prey too often to the allure of wielding the Big Stick. “The Obama approach to national security preserved far more than it changed,” writes Bacevich, “and much of what it was preserving was deeply problematic.” Shortly after taking office, Obama committed an additional 17,000 troops to Afghanistan, expanded the war on terror to new theaters, and increased the use of drone strikes in the Middle East and Africa.

Donald Trump vowed to get America out of the nation-building business during the presidential campaign, but in practice, according to policy experts Robert Malley and John Finer (among others), the Trump administration is carrying out more military operations than its predecessor, against a wider array of adversaries, with looser rules of engagement.

“ American presidents since George H. W. Bush have routinely neglected the wisdom of former secretary of defense William Perry, who once said 'We field an army, not a Salvation Army.' ”

“Washington has become addicted to quick military fixes,” write Malley and Finer in a recent essay in Foreign Affairs. “Sometimes what’s needed is a far broader approach that would entail, where possible, engaging [adversaries] in dialogue and addressing factors such as a lack of education or employment opportunities, ethnic or religious discrimination, the absence of state services, and local government repression. These problems are hard to assess and require political, as opposed to military, solutions—diplomacy rather than warfare.”

In short, American presidents since George H. W. Bush have routinely neglected the wisdom of former secretary of defense William Perry, who once said “We field an army, not a Salvation Army.”

Andrew Bacevich joins noted journalist James Fallows in believing the yawning gap between the American military and the general public—only 1 percent of whom have served in the military—has given interventionists in Washington essentially free reign to commit the military to one misconceived operation after another. A few years ago, Fallows published a long, influential article in The Atlantic, “The Tragedy of the American Military,” in which he argued that while Americans have a deep and abiding respect for the military as an institution, they have become utterly indifferent to what it does in their name all around the world. Americans, he writes, are “reverent but disengaged.”

It’s hard to dispute his point. How many Americans closely follow what their military is up to out there in the wider world? Very few, surely. Professor Bacevich, I’m sure, would agree. As he writes in The New American Militarism, “a people untouched by war are far less likely to care about it. Persuaded that they have no skin in the game, [the American people] will permit the state to do whatever it wishes to.”

Bacevich believes the professional military no longer belongs to the American people, but to a national security establishment that deploys it too often, in the wrong places, at the wrong times. The American people, he says, need to reclaim ownership of their military if they want to get out of the permanent war rut.

To do so, they must revive the citizen-soldier tradition. If more Americans were tied to the military through their own experiences or those of close family members, Washington would doubtless be forced to defend its inclination to deploy armed force much more cogently than it has done over the past few decades.

Many veterans agree. Seth Moulton, the Massachusetts congressman, democratic candidate for president, and Marine veteran of Iraq, has said that if more people in Congress had close connections to the military in 2003, the Iraq War probably never would have happened.

Admiral Mike Mullen, former head of the Joint Chiefs of Staff in the Obama administration, thinks the size of the full-time military should be significantly reduced, so that in a national crisis, the reserves would have to be called up. “That would bring America in. America hasn’t been involved in these previous wars [i.e., Afghanistan and Iraq]. And we are paying dearly for that.”