It’s Hard to Commemorate 9/11 If You Don’t Understand It.

Sept. 11, 2019 marks the 18th anniversary of the deadliest terrorist attack in world history. It also marks a generational shift, with American children born after that date entering adulthood having grown up with their country perpetually fighting a so-called war on terror. The 9/11 attacks and their immediate aftermath belong to an era before Twitter, Instagram, and Facebook.

It’s hard for this younger generation to imagine a time when the U.S. communications system crashed and the Internet seemed to break, at least temporarily, as frantic Americans scrambled to learn about the fate of friends and relatives while false reports and rumors ran rife. In today’s information-saturated environment, it is difficult for them to internalize the confusion of the time, when Americans wondered about the scope of the attack, the perpetrators behind it, and what the country would do in response.

As a professor at Georgetown University who teaches courses on terrorism and counterterrorism, I am reminded every day of how 9/11 is shifting from lived experience to history. My students’ views about al Qaeda are influenced by the emergence of the Islamic State, which captured world attention in 2014 with its beheadings, rapid military advances in Iraq, and declaration of a caliphate—around the time today’s freshmen turned 13. Despite the immediacy of terrorism and its role in the popular imagination, students’ understanding of it is often incomplete, both regarding the danger itself and the U.S. response.

The 9/11 attacks represent an outlier. More than 10 times as many people died on that day as have died in any single terrorist attack before or after in the United States. In the first years after 9/11, my students and I feared that terrorism would grow ever more dangerous: Student papers in that period dwelled on lurid scenarios involving smallpox, miniature armies of jihadi snipers, and other nightmares.

However, even more sober predictions that 9/11 would lead terrorists to escalate further, either in the form of even more spectacular strikes or of chemical, biological, and radiological attacks, have not materialized. The worst jihadi attack on U.S. soil since then—Omar Mateen’s killing of 49 people at the Pulse nightclub in Orlando, Florida, which he claimed was carried out in the name of Islamic State—involved no direct link to the terrorist group and seems more akin to one of the many mass shootings making up the United States’ sorry record on gun violence than to a 9/11-style attack.

In addition to its unique lethality, 9/11 was also an outlier in terms of competence and capability. Mohamed Atta, the quiet and determined commander of the 19 hijackers, initially left Germany because he wanted to fight the Russians in Chechnya and got recruited for the 9/11 operation while training in Afghanistan.

He worked with senior al Qaeda commanders who exploited a truly global network spanning Afghanistan, Europe, Malaysia, and the Persian Gulf states, as well as the United States, to conduct the attacks. Students tend to see Atta and the global training and logistical network on which he drew as the norm, but he was not. He was exceptional.

Indeed, much of my time in the classroom is spent explaining the reasons that terrorists often fail, particularly if they attempt such ambitious plots. A few terrorists are steely-eyed professionals, but most—especially those who operate on U.S. soil—are untrained bumblers, rarely able to build a bomb, let alone orchestrate simultaneous mass-casualty attacks. Rather than keep their heads down, they boast about their plans on social media and are quickly arrested by the FBI. One bragged about the Islamic State flag tattooed on his back. Many do more damage to themselves than they do to the enemy. One Islamic State fighter in Syria blew himself up with his own drone bomb when it exploded after he flew the drone back toward him to replace a low battery.

Others who, like Atta, make it overseas to join a group like al Qaeda or the Islamic State often end up consumed by local civil wars rather than spending their time plotting attacks on the United States, and those who do turn to international terrorism are more likely to be caught and disrupted.

The common conflation of al Qaeda on 9/11 with the Islamic State today sows confusion. The primary goal of the latter was to build and expand its caliphate, and most of the foreigners who went to Syria fought (and many died) there, rather than training for terrorist attacks in the West. Some Islamic State members or supporters did plot and attack in the United States and Europe, but there were far fewer successes than anticipated.

The United States and many other countries have also developed a massive apparatus to identify potential recruits before they go, monitor those who leave, and prevent their travel. In some cases, these governments kill such fighters in foreign war zones. France, for example, worked with Iraqi forces to hunt down French nationals who had joined jihadi groups there.

Before 9/11, terrorists who went to Afghanistan to train entered a black hole, but now governments often  detect and arrest them when they return home or forcibly repatriate them to face justice. Syrian Kurdish-led forces handed over Ruslan Maratovich Asainov, a naturalized U.S. citizen who allegedly served as a sniper for the Islamic State, to U.S. forces, who brought him home to face trial. As a result of these improvements, al Qaeda’s relatively easy penetration of the United States in preparation for the 9/11 attacks would be much harder today.

The response to 9/11 was also unique. The United States quickly went to war in Afghanistan, and the attacks colored the U.S. government’s 2003 decision to invade Iraq. It’s hard to explain the connection, which had much to do with the fearful zeitgeist of 2002 and 2003 and little to do with any actual al Qaeda connection to Iraq. Officials in the administration of U.S. President George W. Bush, however, were able to play up loose connections as a way to beat the drum for war.

The 9/11 attacks also promoted a sense of purpose and unity, which today seems long gone. Both Democrats and Republicans clamored for the U.S. government to get tough on terrorism, and leaders of both parties avoided the scapegoating of minorities. Indeed, Bush made a point of visiting a mosque after 9/11 to underscore his point that a band of fanatics, not Muslims as a community, were responsible for the violence. Tragedy can backfire on the terrorists, promoting unity and making a government stronger.

It can also divide. Under current U.S. President Donald Trump, students find it hard to understand the idea that a terrorist attack might bring people together. After all, Trump used the Orlando attack as an excuse to blast a “dysfunctional immigration system” and an “incompetent administration.” Right-wing terrorist attacks and white supremacist gatherings during his tenure have led him to talk about gun rights and the “very fine people” involved rather than bringing Americans together.

Today’s students also lack a sense of historical perspective. In the late 1960s and early 1970s, there was an average of more than one airplane hijacking per week globally, and those two decades saw hundreds of bombings in the United States by groups ranging from the Ku Klux Klan to the Weather Underground. Indeed, on U.S. soil, both terrorist incidents and fatalities are down in the post-9/11 era compared with the years before.

However, because 9/11 defines what a terrorist incident can do, a bombing or shooting, especially if done by a Muslim in the name of jihad, looms far larger in the imagination than it did in the past. It is hard for students to picture a country remaining relatively calm about a 1970s-level pace of attacks. It is also difficult for them to imagine a U.S. government with only dozens, not tens of thousands, of counterterrorism officers.

Americans who are not fortunate enough to study at an elite university are particularly susceptible to vague threats being used to justify unnecessary government actions.

Although most students would be loath to admit it, based on class discussions they often seem to agree with Trump on some of his assumptions about how to respond to the terrorism threat. They are skeptical of intervention in the Middle East, especially on a massive scale. However, they also accept a grinding set of miniature wars, with air strikes and special-operations force deployments in much of the Muslim world on a near constant basis. They are also comfortable working with dictatorships in the Middle East, seeing this as a necessary price for counterterrorism cooperation. Perhaps most important, they often see every emergence of a jihadi group as a potential threat to the United States, and thus Islamic State-linked attacks in the Democratic Republic of the Congo and Sri Lanka are seen as proof of a continued danger to the United States.

The events of 9/11 are increasingly a memory, and without education that memory can easily become a caricature. Americans who are not fortunate enough to study at an elite university are particularly susceptible to vague threats being used to justify unnecessary government spending or an administration’s preferred policy, without a recognition of how the dangers facing the country have changed since 2001. Capturing all the nuances surrounding 9/11 is vital, but the proper response today also requires recognizing that terrorism is constantly evolving, and when it strikes again it may not come from an expected or familiar source.