9/11 was a test. The books of the last two decades show how America failed.

Deep within the catalogue of regrets that is the 9/11 Commission report — long after readers learn of the origins and objectives of al-Qaeda, past the warnings ignored by consecutive administrations, through the litany of institutional failures that allowed terrorists to hijack four commercial airliners — the authors pause to make a rousing case for the power of the nation’s character.

“The U.S. government must define what the message is, what it stands for,” the report asserts. “We should offer an example of moral leadership in the world, committed to treat people humanely, abide by the rule of law, and be generous and caring to our neighbors. . . . We need to defend our ideals abroad vigorously. America does stand up for its values.”

This affirmation of American idealism is one of the document’s more opinionated moments. Looking back, it’s also among the most ignored.

Rather than exemplify the nation’s highest values, the official response to 9/11 unleashed some of its worst qualities: deception, brutality, arrogance, ignorance, delusion, overreach and carelessness. This conclusion is laid bare in the sprawling literature to emerge from 9/11 over the past two decades — the works of investigation, memoir and narrative by journalists and former officials that have charted the path to that day, revealed the heroism and confusion of the early response, chronicled the battles in and about Afghanistan and Iraq, and uncovered the excesses of the war on terror. Reading or rereading a collection of such books today is like watching an old movie that feels more anguishing and frustrating than you remember. The anguish comes from knowing how the tale will unfold; the frustration from realizing that this was hardly the only possible outcome.

Whatever individual stories the 9/11 books tell, too many describe the repudiation of U.S. values, not by extremist outsiders but by our own hand. The betrayal of America’s professed principles was the friendly fire of the war on terror. In these works, indifference to the growing terrorist threat gives way to bloodlust and vengeance after the attacks. Official dissembling justifies wars, then prolongs them. In the name of counterterrorism, security is politicized, savagery legalized and patriotism weaponized.

It was an emergency, yes, that’s understood. But that state of exception became our new American exceptionalism.

It happened fast. By 2004, when the 9/11 Commission urged America to “engage the struggle of ideas,” it was already too late; the Justice Department’s initial torture memos were already signed, the Abu Ghraib images had already eviscerated U.S. claims to moral authority. And it has lasted long. The latest works on the legacy of 9/11 show how war-on-terror tactics were turned on religious groups, immigrants and protesters in the United States. The war on terror came home, and it walked in like it owned the place.

“It is for now far easier for a researcher to explain how and why September 11 happened than it is to explain the aftermath,” Steve Coll writes in “Ghost Wars,” his 2004 account of the CIA’s pre-9/11 involvement in Afghanistan. Throughout that aftermath, Washington fantasized about remaking the world in its image, only to reveal an ugly image of itself to the world.

The literature of 9/11 also considers Osama bin Laden’s varied aspirations for the attacks and his shifting visions of that aftermath. He originally imagined America as weak and easily panicked, retreating from the world — in particular from the Middle East — as soon as its troops began dying. But bin Laden also came to grasp, perhaps self-servingly, the benefits of luring Washington into imperial overreach, of “bleeding America to the point of bankruptcy,” as he put it in 2004, through endless military expansionism, thus beating back its global sway and undermining its internal unity. “We anticipate a black future for America,” bin Laden told ABC News more than three years before the 9/11 attacks. “Instead of remaining United States, it shall end up separated states and shall have to carry the bodies of its sons back to America.”

Bin Laden did not win the war of ideas. But neither did we. To an unnerving degree, the United States moved toward the enemy’s fantasies of what it might become — a nation divided in its sense of itself, exposed in its moral and political compromises, conflicted over wars it did not want but would not end. When President George W. Bush addressed the nation from the Oval Office on the evening of Sept. 11, 2001, he asserted that America was attacked because it is “the brightest beacon for freedom and opportunity in the world, and no one will keep that light from shining.” Bush was correct; al-Qaeda could not dim the promise of America. Only we could do that to ourselves.

“The most frightening aspect of this new threat . . . was the fact that almost no one took it seriously. It was too bizarre, too primitive and exotic.” That is how Lawrence Wright depicts the early impressions of bin Laden and his terrorist network among U.S. officials in “The Looming Tower: Al-Qaeda and the Road to 9/11.” For a country still basking in its post-Cold War glow, it all seemed so far away, even as al-Qaeda’s strikes — on the World Trade Center in 1993, on U.S. Embassies in 1998, on the USS Cole in 2000 — grew bolder. This was American complacency, mixed with denial.

The books traveling that road to 9/11 have an inexorable, almost suffocating feel to them, as though every turn invariably leads to the first crush of steel and glass. Their starting points vary. Wright dwells on the influence of Egyptian thinker Sayyid Qutb, whose mid-20th-century sojourn in the United States animated his vision of a clash between Islam and modernity, and whose work would inspire future jihadists. In “Ghost Wars,” Coll laments America’s abandonment of Afghanistan once it ceased serving as a proxy battlefield against Moscow. In “The Rise and Fall of Osama bin Laden,” Peter Bergen stresses the moment bin Laden arrived in Afghanistan from Sudan in 1996, when Khalid Sheikh Mohammed first pitched him on the planes plot. And the 9/11 Commission lingers on bin Laden’s declarations of war against the United States, particularly his 1998 fatwa calling it “the individual duty for every Muslim” to murder Americans “in any country in which it is possible.”

Yet these early works also make clear that the road to 9/11 featured plenty of billboards warning of the likely destination. A Presidential Daily Brief item on Aug. 6, 2001, titled “Bin Ladin Determined to Strike in US” became infamous in 9/11 lore, yet the commission report notes that it was the 36th PDB relating to bin Laden or al-Qaeda that year alone. (“All right. You’ve covered your ass now,” Bush reportedly sneered at the briefer.) Both the FBI and the CIA produced classified warnings on terrorist threats in the mid-1990s, Coll writes, including a particularly precise National Intelligence Estimate. “Several targets are especially at risk: national symbols such as the White House and the Capitol, and symbols of U.S. capitalism such as Wall Street,” it stated. “We assess that civil aviation will figure prominently among possible terrorist targets in the United States.” Some of the admonitions scattered throughout the 9/11 literature are too over-the-top even for a movie script: There’s the exasperated State Department official complaining about Defense Department inaction (“Does al Qaeda have to attack the Pentagon to get their attention?”), and the earnest FBI supervisor in Minneapolis warning a skeptical agent in Washington about suspected terrorism activity, insisting that he was “trying to keep someone from taking a plane and crashing it into the World Trade Center.”

In these books, everyone is warning everyone else. Bergen emphasizes that a young intelligence analyst in the State Department, Gina Bennett, wrote the first classified memo warning about bin Laden in 1993. Pockets within the FBI and the CIA obsess over bin Laden while regarding one another as rivals. On his way out, President Bill Clinton warns Bush. Outgoing national security adviser Sandy Berger warns his successor, Condoleezza Rice. And White House counterterrorism coordinator Richard Clarke, as he reminds incessantly in his 2004 memoir, “Against All Enemies,” warns anyone who will listen and many who will not.

With the system “blinking red,” as CIA Director George Tenet later told the 9/11 Commission, why were all these warnings not enough? Wright lingers on bureaucratic failings, emphasizing that intelligence collection on al-Qaeda was hampered by the “institutional warfare” between the CIA and the FBI, two agencies that by all accounts were not on speaking terms. Coll writes that Clinton regarded bin Laden as “an isolated fanatic, flailing dangerously but quixotically against the forces of global progress,” whereas the Bush team was fixated on great-power politics, missile defense and China.

Clarke’s conclusion is simple, and it highlights America’s we-know-better swagger, a national trait that often masquerades as courage or wisdom. “America, alas, seems only to respond well to disasters, to be undistracted by warnings,” he writes. “Our country seems unable to do all that must be done until there has been some awful calamity.”

The problem with responding only to calamity is that underestimation is usually replaced by overreaction. And we tell ourselves it is the right thing, maybe the only thing, to do.

A last-minute flight change. A new job at the Pentagon. A retirement from the fire station. The final tilt of a plane’s wings before impact. If the books about the lead-up to 9/11 are packed with unbearable inevitability, the volumes on the day itself highlight how randomness separated survival from death. “The ferocity of the attacks meant that innocent people lived or died because they stepped back from a doorway, or hopped onto a closing elevator, or simply shifted their weight from one foot to another,” Jim Dwyer and Kevin Flynn write in “102 Minutes,” their narrative of events inside the World Trade Center from the moment the first plane hit through the collapse of both towers. Their detailed reporting on the human saga — such as a police officer asking a fire chaplain to hear his confession as they both flee a collapsing building — is excruciating and riveting at once.

Yet, as much as the people inside, the structures and history of the World Trade Center are key actors, too. They are not just symbols and targets but fully formed and deeply flawed characters in the day’s drama.

Had the World Trade Center, built in the late 1960s and early 1970s, been erected according to the city building code in effect since 1938, Dwyer and Flynn explain, “it is likely that a very different world trade center would have been built.” Instead, it was constructed according to a new code that the real estate industry had avidly promoted, a code that made it cheaper and more lucrative to build and own skyscrapers. “It increased the floor space available for rent . . . by cutting back on the areas that had been devoted, under the earlier law, to evacuation and exit,” the authors write. The result: Getting everybody out on 9/11 was virtually impossible.

Under the new rules, the Port Authority of New York and New Jersey was able to rent three-quarters of each floor of the World Trade Center, Dwyer and Flynn report, a 21 percent increase over the yield of older skyscrapers. The cost was dear. Some 1,000 people inside the North Tower who initially survived the impact of American Airlines Flight 11 could not reach an open staircase. “Their fate was sealed nearly four decades earlier, when the stairways were clustered in the core of the building, and fire stairs were eliminated as a wasteful use of valuable space.” (The authors write that “building code reform hardly makes for gripping drama,” an aside as modest as it is inaccurate.) The towers embodied the power of American capitalism, but their design embodied the folly of American greed. On that day, both conditions proved fatal.

The assault on the Pentagon, long treated as an undercard to New York’s main event, could have yielded even greater devastation, and again the details of the building played a role. In his oral history of 9/11, “The Only Plane in the Sky,” Garrett Graff quotes Defense Department officials marveling at how American Airlines Flight 77 struck a part of the Pentagon that, because of new anti-terrorism standards, had recently been reinforced and renovated. This meant it was not only stronger but, on that morning, also relatively unoccupied. “It was truly a miracle,” Army branch chief Philip Smith said. “In any other wedge of the Pentagon, there would have been 5,000 people, and the plane would have flown right through the middle of the building.” Instead, fewer than 200 people were killed in the attack on the Pentagon, including the passengers on the hijacked jet. Chance and preparedness came together.

The bravery of police and firefighters is the subject of countless 9/11 retrospectives, but these books also emphasize the selflessness of civilians who morphed into first responders. Port Authority workers Frank De Martini, Pablo Ortiz, Carlos da Costa and Peter Negron, for instance, saved at least 70 people in the World Trade Center’s North Tower by pulling apart elevator doors, busting walls and shining flashlights to find survivors, only to not make it out themselves. “With crowbar, flashlight, hardhat and big mouths, De Martini and Ortiz and their colleagues had pushed back the boundary line between life and death,” Dwyer and Flynn write. The authors also note how the double lines of people descending a World Trade Center staircase would automatically blend into single file when word came down that an injured person was behind them. And Graff cites a local assistant fire chief who recalls the “truly heroic” work of civilians and uniformed personnel at the Pentagon that day. “They were the ones who really got their comrades, got their workmates out,” he says.

The civilians aboard United Airlines Flight 93, whose resistance forced the plane to crash into a Pennsylvania field rather than the U.S. Capitol, were later lionized as emblems of swashbuckling Americana. But one offhand detail in the 9/11 Commission report underscores just how American their defiance was. The passengers had made phone calls when the hijacking began and had learned the fate of other aircraft that day. “According to one call, they voted on whether to rush the terrorists in an attempt to retake the plane,” the commission report states. “They decided, and acted.”

They voted on it. They voted. Even in that moment of unfathomable fear and distress, the passengers took a moment to engage in the great American tradition of popular consultation before deciding to become this new war’s earliest soldiers. Was there ever any doubt as to the outcome of that ballot?

Such episodes, led by ordinary civilians, embodied values that the 9/11 Commission called on the nation to display. Except those values would soon be dismantled, in the name of security, by those entrusted to uphold them.

Lawyering to death.

The phrase appears in multiple 9/11 volumes, usually uttered by top officials adamant that they were going to get things done, laws and rules be damned. Anti-terrorism efforts were always “lawyered to death” during the Clinton administration, Tenet complains in “Bush at War,” Bob Woodward’s 2002 book on the debates among the president and his national security team. In an interview with Woodward, Bush drops the phrase amid the machospeak — “dead or alive,” “bring ’em on” and the like — that became typical of his anti-terrorism rhetoric. “I had to show the American people the resolve of a commander in chief that was going to do whatever it took to win,” Bush explains. “No yielding. No equivocation. No, you know, lawyering this thing to death.” In “Against All Enemies,” Clarke recalls the evening of Sept. 11, 2001, when Bush snapped at an official who suggested that international law looked askance at military force as a tool of revenge. “I don’t care what the international lawyers say, we are going to kick some ass,” the president retorted.

The message was unmistakable: The law is an obstacle to effective counterterrorism. Worrying about procedural niceties is passe in a 9/11 world, an annoying impediment to the essential work of ass-kicking.

Except, they did lawyer this thing to death. Instead of disregarding the law, the Bush administration enlisted it. “Beginning almost immediately after September 11, 2001, [Vice President Dick] Cheney saw to it that some of the sharpest and best-trained lawyers in the country, working in secret in the White House and the United States Department of Justice, came up with legal justifications for a vast expansion of the government’s power in waging war on terror,” Jane Mayer writes in “The Dark Side,” her relentless 2008 compilation of the arguments and machinations of government lawyers after the attacks. Through public declarations and secret memos, the administration sought to remove limits on the president’s conduct of warfare and to deny terrorism suspects the protections of the Geneva Conventions by redefining them as unlawful enemy combatants. Nothing, Mayer argues of the latter effort, “more directly cleared the way for torture than this.”

To comprehend what our government can justify in the name of national security, consider the torture memos themselves, authored by the Justice Department’s Office of Legal Counsel between 2002 and 2005 to green-light CIA interrogation methods for terrorism suspects. Tactics such as cramped confinement, sleep deprivation and waterboarding were rebranded as “enhanced interrogation techniques,” legally and linguistically contorted to avoid the label of torture. Though the techniques could be cruel and inhuman, the OLC acknowledged in an August 2002 memo, they would constitute torture only if they produced pain equivalent to organ failure or death, and if the individual inflicting such pain really really meant to do so: “Even if the defendant knows that severe pain will result from his actions, if causing such harm is not his objective, he lacks the requisite specific intent.” It’s quite the sleight of hand, with torture moving from the body of the interrogated to the mind of the interrogator.

After devoting dozens of pages to the metaphysics of specific intent, the true meaning of “prolonged” mental harm or “imminent” death, and the elasticity of the Convention Against Torture, the memo concludes that none of it actually matters. Even if a particular interrogation method would cross some legal line, the relevant statute would be considered unconstitutional because it “impermissibly encroached” on the commander in chief’s authority to conduct warfare. Almost nowhere in these memos does the Justice Department curtail the power of the CIA to do as it pleases.

In fact, the OLC lawyers rely on assurances from the CIA itself to endorse such powers. In a second memo from August 2002, the lawyers ruminate on the use of cramped confinement boxes. “We have no information from the medical experts you have consulted that the limited duration for which the individual is kept in the boxes causes any substantial physical pain,” the memo states. Waterboarding likewise gets a pass. “You have informed us that this procedure does not inflict actual physical harm,” the memo states. “Based on your research . . . you do not anticipate that any prolonged mental harm would result from the use of the waterboard.”

You have informed us. Experts you have consulted. Based on your research. You do not anticipate. Such hand-washing words appear throughout the memos. The Justice Department relies on information provided by the CIA to reach its conclusions; the CIA then has the cover of the Justice Department to proceed with its interrogations. It’s a perfect circle of trust.

Yet the logic is itself tortured. In a May 2005 memo, the lawyers conclude that because no single technique inflicts “severe” pain amounting to torture, their combined use “would not be expected” to reach that level, either. As though embarrassed at such illogic, the memo attaches a triple-negative footnote: “We are not suggesting that combinations or repetitions of acts that do not individually cause severe physical pain could not result in severe physical pain.” Well, then, what exactly are you suggesting?

In these documents, lawyers enable lawlessness. Another May 2005 memo concludes that, because the Convention Against Torture applies only to actions occurring under U.S. jurisdiction, the CIA’s creation of detention sites in other countries renders the convention “inapplicable.” Similarly, because the Eighth Amendment’s prohibition on cruel and unusual punishment is meant to protect people convicted of crimes, it should not apply to terrorism detainees — because they have not been officially convicted of anything. The lack of due process conveniently eliminates constitutional protections. In his introduction to “The Torture Memos: Rationalizing the Unthinkable,” David Cole describes the documents as “bad-faith lawyering,” which might be generous. It is another kind of lawyering to death, one in which the rule of law that the 9/11 Commission urged us to abide by becomes the victim.

Years later, the Senate Intelligence Committee would investigate the CIA’s post-9/11 interrogation program. Its massive report — the executive summary of which appeared as a 549-page book in 2014 — found that torture did not produce useful intelligence, that the interrogations were more brutal than the CIA let on, that the Justice Department did not independently verify the CIA’s information, and that the spy agency impeded oversight by Congress and the CIA inspector general. It explains that the CIA purported to oversee itself and, no surprise, that it deemed its interrogations effective and necessary, no matter the results. (If a detainee provided information, it meant the program worked; if he did not, it meant stricter applications of the techniques were needed; if still no information was forthcoming, the program had succeeded in proving he had none to give.)

“The CIA’s effectiveness representations were almost entirely inaccurate,” the Senate report concluded. It is one of the few lies of the war on terror unmasked by an official government investigation and public report, but just one of the many documented in the 9/11 literature.

Officials in the war on terror didn’t deceive or dissemble just with lawmakers or the public. In the recurring tragedy of war, they lied just as often to themselves.

In “To Start a War: How the Bush Administration Took America Into Iraq,” Robert Draper considers the influence of the president’s top aides. Deputy Defense Secretary Paul Wolfowitz (long obsessed with ousting Saddam Hussein), Pentagon chief Donald Rumsfeld (eager to test his theories of military transformation) and Cheney (fixated on apocalyptic visions of America’s vulnerability) all had their reasons. But Draper identifies a single responsible party: “The decision to invade Iraq was one made, finally and exclusively, by the president of the United States, George W. Bush,” he writes.

A president initially concerned about defending and preserving the nation’s moral goodness against terrorism found himself driven by darker impulses. “I’m having difficulty controlling my bloodlust,” Bush confessed to religious leaders in the Oval Office on Sept. 20, 2001, Draper reports. It was not a one-off comment; in Woodward’s “Bush at War,” the president admitted that before 9/11, “I didn’t feel that sense of urgency [about al-Qaeda], and my blood was not nearly as boiling.”

Bloodlust, moral certainty and sudden vulnerability make a dangerous combination. The belief that you are defending good against evil can lead to the belief that whatever you do to that end is good, too. Draper distills Bush’s worldview: “The terrorists’ primary objective was to destroy America’s freedom. Saddam hated America. Therefore, he hated freedom. Therefore, Saddam was himself a terrorist, bent on destroying America and its freedom.”

Note the asymmetry. The president assumed the worst about what Hussein had done or might do, yet embraced best-case scenarios of how an American invasion would proceed. “Iraqis would rejoice at the sight of their Western liberators,” Draper recaps. “Their newly shared sense of national purpose would overcome any sectarian allegiances. Their native cleverness would make up for their inexperience with self-government. They would welcome the stewardship of Iraqi expatriates who had not set foot in Baghdad in decades. And their oil would pay for everything.”

There are lies, and then there is self-delusion. The Americans did not have to anticipate the specifics of the civil war that would engulf the country after the invasion; they just had to realize that managing postwar Iraq would never be as simple as they imagined. It did not seem to occur to Bush and his advisers that Iraqis could simultaneously hate Hussein and resent the Americans — feelings that could have been discovered by speaking to Iraqis and hearing their concerns.

Anthony Shadid’s “Night Draws Near: Iraq’s People in the Shadow of America’s War,” published in 2005, is among the few books on the war that gets deep inside Iraqis’ aversion to the Americans in their midst. “What gives them the right to change something that’s not theirs in the first place?” a woman in a middle-class Baghdad neighborhood asks him. “I don’t like your house, so I’m going to bomb it and you can rebuild it again the way I want it, with your money?” In Fallujah, where Shadid hears early talk of the Americans as “kuffar” (heathens), a 51-year-old former teacher complains that “we’ve exchanged a tyrant for an occupier.” The occupation did not dissuade such impressions when it turned the former dictator’s seat of government into its own luxurious Green Zone, or when it retrofitted the Abu Ghraib prison (“the worst of Saddam’s hellholes,” Shadid calls it) into its own chamber of horrors.

Shadid understood that governmental legitimacy — who gets to rule, and by what right — was a matter of overriding importance for Iraqis. “The Americans never understood the question,” he writes; “Iraqis never agreed on the answer.” It’s hard to find a better summation of the trials of Iraq in the aftermath of America’s invasion. When the United States so quickly shifted from liberation to occupation, it lost whatever legitimacy it enjoyed. “Bush handed that enemy precisely what it wanted and needed, proof that America was at war with Islam, that we were the new Crusaders come to occupy Muslim land,” Clarke writes. “It was as if Usama bin Laden, hidden in some high mountain redoubt, were engaging in long-range mind control of George Bush, chanting ‘invade Iraq, you must invade Iraq.’ ”

The foolishness and arrogance of the American occupation didn’t help. In “Imperial Life in the Emerald City: Inside Iraq’s Green Zone,” Rajiv Chandrasekaran explains how, even as daily security was Iraqis’ overwhelming concern, viceroy L. Paul Bremer, Bush’s man in Baghdad, was determined to turn the country into a model free-market economy, complete with new investment laws, bankruptcy courts and a state-of-the-art stock exchange. In charge of the new exchange was a 24-year-old American with no academic background in economics or finance. The man tasked with remaking Iraq’s sprawling university system had no experience in the Middle East — but did have connections to the Rumsfeld and Cheney families. A new traffic law for Iraq was partially cut and pasted from Maryland’s motor vehicle code. An antismoking campaign was led by a U.S. official who was a closet smoker. And a U.S. Army general, when asked by local journalists why American helicopters must fly so low at night, thus scaring Iraqi children, replied that the kids were simply hearing “the sound of freedom.”

Message: Freedom sounds terrifying.

For some Americans, inflicting that terror became part of the job, one more tool in the arsenal. In “The Forever War” by Dexter Filkins, a U.S. Army lieutenant colonel in Iraq assures the author that “with a heavy dose of fear and violence, and a lot of money for projects, I think we can convince these people that we are here to help them.” (Filkins asked him if he really meant it about fear and violence; the officer insisted that he did.) Of course, not all officials were so deluded and so forthright; some knew better but lied to the public. Chandrasekaran recalls the response of a top communications official under Bremer, when reporters asked about waves of violence hitting Baghdad in the spring of 2004. “Off the record: Paris is burning,” the official told the journalists. “On the record: Security and stability are returning to Iraq.”

In “The Rise and Fall of Osama bin Laden,” Bergen sums up how the Iraq War, conjured in part on the false connections between Iraq and al-Qaeda, ended up helping the terrorist network: It pulled resources from the war in Afghanistan, gave space for bin Laden’s men to regroup and spurred a new generation of terrorists in the Middle East. “A bigger gift to bin Laden was hard to imagine,” Bergen writes.

If Iraq was the war born of lies, Afghanistan was the one nurtured by them. Afghanistan was where al-Qaeda, supported by the Taliban, had made its base — it was supposed to be the good war, the right war, the war of necessity and not choice, the war endorsed at home and abroad. “U.S. officials had no need to lie or spin to justify the war,” Washington Post reporter Craig Whitlock writes in “The Afghanistan Papers,” a damning contrast of the war’s reality vs. its rhetoric. “Yet leaders at the White House, the Pentagon and the State Department soon began to make false assurances and to paper over setbacks on the battlefield.” As the years passed, the deceit became entrenched, what Whitlock calls “an unspoken conspiracy” to hide the truth.

Drawing from a “Lessons Learned” project that interviewed hundreds of military and civilian officials involved with Afghanistan, as well as from oral histories, government cables and reports, Whitlock finds commanding generals privately admitting that they long fought the war “without a functional strategy.” That, two years into the conflict, Rumsfeld complained that he had “no visibility into who the bad guys are.” That Army Lt. Gen. Douglas Lute, a former coordinator of Iraq and Afghanistan policy, acknowledged that “we didn’t have the foggiest idea of what we were undertaking.” That U.S. officials long wanted to withdraw American forces but feared — correctly so, it turns out — that the Afghan government might collapse. “Bin Laden had hoped for this exact scenario,” Whitlock observes. “To lure the U.S. superpower into an unwinnable guerrilla conflict that would deplete its national treasury and diminish its global influence.”

All along, top officials publicly contradicted these internal views, issuing favorable accounts of steady progress. Bad news was twisted into good: Rising suicide attacks in Kabul meant the Taliban was too weak for direct combat, for instance, while increased U.S. casualties meant America was taking the fight to the enemy. The skills and size of the Afghan security forces were frequently exaggerated; by the end of President Barack Obama’s second term, U.S. officials concluded that some 30,000 Afghan soldiers on the payroll didn’t actually exist, mere paper creations of local commanders who pocketed the fake soldiers’ salaries at U.S. taxpayer expense. American officials publicly lamented large-scale corruption in Afghanistan but enabled that corruption in practice, pouring massive contracts and projects into a country ill-equipped to absorb them. Such deceptions transpired across U.S. presidents, but the Obama administration, eager to show that its first-term troop surge was working, “took it to a new level, hyping figures that were misleading, spurious or downright false,” Whitlock writes. And then under President Donald Trump, he adds, the generals felt pressure to “speak more forcefully and boast that his war strategy was destined to succeed.”

Long before President Biden declared the end of the U.S. war in Afghanistan this summer, the United States twice made similar pronouncements, proclaiming the conclusion of combat operations in 2003 and again in 2014 — yet still the war endured. It did so in part because “in public, almost no senior government officials had the courage to admit that the United States was slowly losing,” Whitlock writes. “With their complicit silence, military and political leaders avoided accountability and dodged reappraisals that could have changed the outcome or shortened the conflict.”

It’s not like nobody warned them. In “Bush at War,” Woodward reports that CIA Counterterrorism Center Director Cofer Black and Deputy Secretary of State Richard Armitage traveled to Moscow shortly after 9/11 to give officials a heads up about the coming hostilities in Afghanistan. The Russians, recent visitors to the graveyard of empires, cautioned that Afghanistan was an “ambush heaven” and that, in the words of one of them, “you’re really going to get the hell kicked out of you.” Cofer responded confidently: “We’re going to kill them. . . . We’re going to rock their world.”

Now, with U.S. forces gone and the Taliban having reclaimed power in Afghanistan, Washington is wrestling with the legacy of the nation’s longest war. Why and how did America lose? Should we have stayed longer? Was it worth its price in blood and billions? How does the United States repay the courage of Afghans who worked alongside U.S. military and civilian authorities? What if Afghanistan again becomes a haven for terrorists attacking U.S. interests and allies, as the airport suicide bombing in Kabul that killed 13 U.S. service members last month may signal? Biden has asserted that “the war in Afghanistan is now over” but has also pledged to continue the fight against terrorists there — so what are the limits and the means of future U.S. military and intelligence action in the country?

These are essential debates, but a war should not be measured only by the timing and the competence of its end. We still face an equally consequential appraisal: How good was this good war if it could be sustained only by lies?

In the two decades since the 9/11 attacks, the United States has often attempted to reconsider its response. Take two documents from late 2006: the report from the Iraq Study Group, co-chaired by James A. Baker III and Lee H. Hamilton, which argued that Washington needed to radically rethink its diplomatic and political strategy for Iraq; and “The U.S. Army/Marine Corps Counterinsurgency Field Manual,” led by then-Army Lt. Gen. David H. Petraeus, which argued that U.S. officials needed to radically rethink military tactics for insurgency wars of the kind it faced in Iraq and Afghanistan.

They are written as though intending to solve problems. But they can be read as proof that the problems have no realistic solution, or that the only solution is to never have created them.

“There is no magic formula to solve the problems of Iraq,” the ISG report begins, yet its proposed fixes would have required plenty of fairy dust. The report calls for a “diplomatic offensive” to gain international support for Iraq, to persuade Iran and Syria to respect Iraq’s territory and sovereignty, and to commit to “a comprehensive Arab-Israeli peace on all fronts.” Simple! Iraq, meanwhile, needed to make progress on national reconciliation (in a country already awash in sectarian bloodletting), boost domestic security (even though the report deems the Iraqi army a mess and the Iraqi police worse) and deliver social services (even as the report concludes that the government was failing to adequately provide electricity, drinking water, sewage services and education).

The recommendations seem written in the knowledge that they will never happen. “Miracles cannot be expected,” the report states — twice. Absent divine intervention, the next step is obvious. If the Iraqi government can’t demonstrate “substantial progress” toward its goals, the report asserts, “the United States should reduce its political, military, or economic support” for Iraq. Indeed, the report sets the bar for staying so high that an exit strategy appears to be its primary purpose.

The counterinsurgency manual is an extraordinary document. Implicitly repudiating notions such as “shock and awe” and “overwhelming force,” it argues that the key to battling an insurgency in countries such as Iraq and Afghanistan is to provide security for the local population and to win its support through effective governance. It also attempts to grasp the nature of America’s foes. “Most enemies either do not try to defeat the United States with conventional operations or do not limit themselves to purely military means,” the manual states. “They know that they cannot compete with U.S. forces on those terms. Instead, they try to exhaust U.S. national will.” Exhausting America’s will is an objective that al-Qaeda understood well.

“Soldiers and Marines are expected to be nation builders as well as warriors,” the manual proclaims, but the arduous tasks involved — reestablishing government institutions, rebuilding infrastructure, strengthening local security forces, enforcing the rule of law — reveal the tension at the heart of the new doctrine. “Counterinsurgents should prepare for a long-term commitment,” the manual states. Yet, just a few pages later, it admits that “eventually all foreign armies are seen as interlopers or occupiers.” How to accomplish the former without descending into the latter? No wonder so many of the historical examples of counterinsurgency that the manual highlights, including accounts from the Vietnam War, are stories of failure.

The manual seems aware of its importance. The 2007 edition contains a foreword, followed by an introduction, then another foreword, a preface, then some brief acknowledgments and finally one more introduction. (Just reaching Chapter 1 feels like defeating an insurgency.) But the throat-clearing is clarifying. In his foreword, Army Lt. Col. John Nagl writes that the document’s most lasting impact may be as a catalyst not for remaking Iraq or Afghanistan, but for transforming the Army and Marine Corps into “more effective learning organizations,” better able to adapt to changing warfare. And in her introduction, Sarah Sewall, then director of Harvard’s Carr Center for Human Rights Policy, concludes that its “ultimate value” may be in warning civilian officials to think hard before engaging in a counterinsurgency campaign.

At best, then, the manual helps us rethink future conflicts — how we fight and whether we should. It’s no coincidence that Biden, in his Aug. 16 remarks defending the decision to withdraw American troops from Afghanistan, specifically repudiated counterinsurgency as an objective of U.S. policy. “I’ve argued for many years that our mission should be narrowly focused on counterterrorism, not counterinsurgency or nation-building,” the president affirmed. Even the longest war was not long enough for a counterinsurgency effort to succeed.

In his 2009 book, “The Good Soldiers,” David Finkel chronicles the experiences of an Army battalion deployed in Iraq during the U.S. troop surge in 2007 and 2008, a period of the war ostensibly informed by the new counterinsurgency doctrine. In his 2013 sequel, “Thank You for Your Service,” the author witnesses these men when they come home and try to make sense of their military experience and adapt to their new lives. “The thing that got to everyone,” Finkel explains in the latter book, “was not having a defined front line. It was a war in 360 degrees, no front to advance toward, no enemy in uniform, no predictable patterns, no relief.” It’s a powerful summation of battling an insurgency.

Adam Schumann returns from war because of post-traumatic stress disorder and traumatic brain injury, “the result of a mortar round that dropped without warning out of a blue sky,” Finkel explains. Schumann suffers from nightmares, headaches and guilt; he wishes he needed bandages or crutches, anything to visibly justify his absence from the front. His wife endures his treatments, his anger, his ambivalence toward life. “He’s still a good guy,” she decides. “He’s just a broken good guy.” Another returning soldier, Nic DeNinno, struggles to tell his wife about the time he and his fellow soldiers burst into an Iraqi home in search of a high-value target. He threw a man down the stairs and held another by the throat. After they left, the lieutenant told him it was the wrong house. “The wrong f---ing house,” Nic says to his wife. “One of the things I want to remember is how many times we hit the wrong house.”

Hitting the wrong house is what counterinsurgency doctrine is supposed to avoid. Even successfully capturing or killing a high-value target can be counterproductive if in the process you terrorize a community and create more enemies. In Iraq, the whole country was the wrong house. America’s leaders knew it was the wrong house. They hit it anyway.

In the 11th chapter of the 9/11 Commission report, just before all the recommendations for reforms in domestic and foreign policy, the authors get philosophical, pondering how hindsight had affected their views of Sept. 11, 2001. “As time passes, more documents become available, and the bare facts of what happened become still clearer,” the report states. “Yet the picture of how those things happened becomes harder to reimagine, as that past world, with its preoccupations and uncertainty, recedes.” Before making definitive judgments, then, they ask themselves “whether the insights that seem apparent now would really have been meaningful at the time.”

It’s a commendable attitude, one that helps readers understand what the attacks felt like in real time and why authorities responded as they did. But that approach also keeps the day trapped in the past, safely distant. Two of the latest additions to the canon, “Reign of Terror” by Spencer Ackerman and “Subtle Tools” by Karen Greenberg, draw straight, stark lines between the earliest days of the war on terror and its mutations in our current time, between conflicts abroad and divisions at home. These works show how 9/11 remains with us, and how we are still living in the ruins.

When Trump declared that “we don’t have victories anymore” in his 2015 speech announcing his presidential candidacy, he was both belittling the legacy of 9/11 and harnessing it to his ends. “His great insight was that the jingoistic politics of the War on Terror did not have to be tied to the War on Terror itself,” Ackerman writes. “That enabled him to tell a tale of lost greatness.” And if greatness is lost, someone must have taken it. The backlash against Muslims, against immigrants crossing the southern border and against protesters rallying for racial justice was strengthened by the open-ended nature of the global war on terror. In Ackerman’s vivid telling — his prose can be hyperbolic, even if his arguments are not — the war is not just far away in Iraq or Afghanistan, in Yemen or Syria, but it’s happening here, with mass surveillance, militarized law enforcement and the rebranding of immigration as a threat to the nation’s security rather than a cornerstone of its identity. “Trump had learned the foremost lesson of 9/11,” Ackerman writes, “that the terrorists were whomever you said they were.”

Both Ackerman and Greenberg point to the Authorization for Use of Military Force, drafted by administration lawyers and approved by Congress just days after the attacks, as the moment when America’s response began to go awry. The brief joint resolution allowed the president to use “all necessary and appropriate force” against any nation, organization or person who committed the attacks, and to prevent any future ones. It was the “Ur document in the war on terror and its legacy,” Greenberg writes. “Riddled with imprecision, its terminology was geared to codify expansive powers.” Where the battlefield, the enemy and the definition of victory all remain vague, war becomes endlessly expansive, “with neither temporal nor geographical boundaries.”

This was the moment the war on terror was “conceptually doomed,” Ackerman concludes. This is how you get a forever war.

There were moments when an off-ramp was visible. The killing of bin Laden in 2011 was one such instance, Ackerman argues, but “Obama squandered the best chance anyone could ever have to end the 9/11 era.” The author assails Obama for making the war on terror more “sustainable” through a veneer of legality — banning torture yet failing to close the detention camp at Guantánamo Bay and relying on drone strikes that “perversely incentivized the military and the CIA to kill instead of capture.” There would always be more targets, more battlefields, regardless of president or party. Failures became the reason to double down, never wind down.

The longer the war went on, the more that what Ackerman calls its “grotesque subtext” of nativism and racism would move to the foreground of American politics. Absent the war on terror, it is harder to imagine a presidential candidate decrying a sitting commander in chief as foreign, Muslim, illegitimate — and using that lie as a successful political platform. Absent the war on terror, it is harder to imagine a travel ban against people from Muslim-majority countries. Absent the war on terror, it is harder to imagine American protesters labeled terrorists, or a secretary of defense describing the nation’s urban streets as a “battle space” to be dominated. Trump was a disruptive force in American life, but there was much continuity there, too. “A vastly different America has taken root” in the two decades since 9/11, Greenberg writes. “In the name of retaliation, ‘justice,’ and prevention, fundamental values have been cast aside.”

In his latest book on bin Laden, Bergen argues that 9/11 was a major tactical success but a long-term strategic failure for the terrorist leader. Yes, he struck a vicious blow against “the head of the snake,” as he called the United States, but “rather than ending American influence in the Muslim world, the 9/11 attacks greatly amplified it,” with two lengthy, large-scale invasions and new bases established throughout the region.

Yet the legacy of the 9/11 era is found not just in Afghanistan or Iraq, but also in an America that drew out and heightened some of its ugliest impulses — a nation that is deeply divided (like those “separated states” bin Laden imagined); that bypasses inconvenient facts and embraces conspiracy theories; that demonizes outsiders; and that, after failing to spread freedom and democracy around the world, seems less inclined to uphold them here. More Americans today are concerned about domestic extremism than foreign terrorism, and on Jan. 6, 2021, our own citizens assaulted the Capitol building that al-Qaeda hoped to strike on Sept. 11, 2001. Seventeen years after the 9/11 Commission called on the United States to offer moral leadership to the world and to be generous and caring to our neighbors, our moral leadership is in question, and we can barely be generous and caring to ourselves.

In “The Forever War,” Dexter Filkins describes a nation in which “something had broken fundamentally after so many years of war . . . there had been some kind of primal dislocation between cause and effect, a numbness wholly understandable, necessary even, given the pain.” He was writing of Afghanistan, but his words could double as an interpretation of the United States over the past two decades. Still reeling from an attack that dropped out of a blue sky, America is suffering from a sort of post-traumatic stress democracy. It remains in recovery, still a good country, even if a broken good country.

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