A person touches the name of a victim inscribed on the National September 11 Memorial on the 20th anniversary of the Sept. 11, 2001 attacks in New York on Saturday, Sept. 11, 2021.

Mike Segar/Pool Photo via AP

Mike Segar/Pool Photo via AP

A person touches the name of a victim inscribed on the National September 11 Memorial on the 20th anniversary of the September 11, 2001 attacks in New York on Saturday, September 11, 2021.

Report - Belfer Center for Science and International Affairs, Harvard Kennedy School

Report - 9/11: Intelligence and National Security Twenty Years Later

| Sep. 23, 2021

Highlights of conference contemplating causes, effects of 9/11

Featured in the Fall 2021 Newsletter »

The attacks on September 11, 2001 profoundly altered America’s society and national security. Moments of painstaking agony and astonishing courage played out side by side at the World Trade Center, the Pentagon, and on flight United 93. As victims and first responders grasped for life, grief and deep insecurity enveloped the country. For the United States Intelligence Community, it was a transformational event that drove public servants to unprecedented lengths to keep America safe in a world dramatically outpacing the one envisioned within the National Security Act of 1947. Now at the turn of the century and in the face of terror, the U.S. government’s response was swift and decisive. America and allies toppled the Taliban in just a few short months and severely limited Al Qaeda’s ability to operate in Afghanistan. Over the coming years that limited action in Afghanistan morphed into a Global War on Terror. Twenty years later, following America’s chaotic withdrawal, the Taliban is back in power—an outcome that few would have predicted that fateful day two decades ago.

The events of 9/11 underscored the dynamic nature of evolving threats in the twenty-first century. Delineations of domestic and foreign intelligence blurred along fractured spaces, redefining the boundaries and lexicon of national security. At home in America, the impact of 9/11 continues to echo throughout society. Many still list terrorism as a top policy concern despite changes in the threat landscape. 9/11 also continues to affect the relationship between policy and intelligence. Too many policymakers remain wedded to intelligence as a function of prediction versus an empowering decision advantage to influence events as they unfold. Together, intelligence and policy can shape possible outcomes in favor of American interests and avoid tragic moments like 9/11.


Paul Kolbe provides opening remarks.

Contemplating the causes and effects of 9/11, as well as the experiences of those on the ground that day, yields useful insights into tackling today’s intelligence and policy challenges. This report is derived from a full-day conference hosted by the Belfer Center’s Intelligence Project that examined the impact of 9/11 through personal stories and policy reflections. 9/11: Intelligence and National Security Twenty Years Later explored how strategic intelligence on Al Qaeda’s intentions failed to lead to policy changes that could have prevented the attacks on 9/11. The event also examined how the U.S. can draw on the experience of 9/11 as it faces the specter of great power competition with China against the backdrop of globalized, existential threats posed by climate change and novel disease outbreaks like COVID-19. The participants also explored the critical nexus between intelligence warning and policy action. More broadly, the twentieth anniversary of 9/11 is an opportunity to reflect on who we are as a nation and who we want to be in confronting violent extremism—both at home and around the world.


Intelligence and the Paradox of Prevention

As it became clear that the attacks on the morning of 9/11 were part of a coordinated plot, many national security experts immediately identified Al Qaeda as the likely perpetrator. The U.S. Intelligence Community (IC) had gathered significant intelligence on Al Qaeda over the past decade, yielding insights into its capabilities and intentions. Michael Morell, former acting director of the CIA and the president’s daily briefer on 9/11, told the conference that the strategic warnings the U.S. IC issued concerning Al Qaeda and Osama bin Laden could be considered one of the greatest successes in its history. The agency’s warnings on the evolving capabilities and malign intentions of this non-state actor and their strategic objectives came long before this tragic September morning.

The CIA first warned about bin Laden as early as 1992. By 1996 the agency assessed that Al Qaeda was seeking to overthrow Arab leaders, drive the U.S. military from the Middle East, and establish an Islamic caliphate. Al Qaeda sought to attack the U.S. everywhere, even at the homeland, and sought weapons of mass destruction to aid their endeavor. Those warnings proved accurate. In August 1998, Al Qaeda bombed the U.S. embassies in Dar es Salaam and Nairobi, killing over 200 people. In October 2000, they carried out a suicide attack on the USS Cole in Yemen, killing 17 U.S. sailors and injuring dozens of others. During the millennium celebrations, U.S. intelligence developed insights into specific plans and procedures to thwart multiple attacks, including one targeting Los Angeles International Airport. By September 2001, the U.S. IC and policymakers were well aware that Al Qaeda and bin Laden posed a threat, but few among the general public even knew who they were.

Philip Zelikow on the paradox of prevention.

Philip Zelikow, Executive Director of the 9/11 Commission, observed that this sequence of events embodies a paradox of prevention. Despite the strategic warnings from the U.S. IC, and the clear evidence that Al Qaeda sought to realize their threats, it was difficult to mount a major policy effort to prevent a large-scale attack. Once the attacks on 9/11 occurred, the problem and policy solutions were defined and understood, but it was too late to prevent it. In some ways the paradox of prevention clears policymakers of responsibility for their own inaction. There was an intelligence failure in that American intelligence failed to capitalize on collected tactical intelligence to disrupt the 9/11 attacks. Left unsaid by many critics of the Intelligence Community was the role of cascading policy failure across administrations. If the Clinton and Bush administrations had implemented policy changes in response to strategic warnings, they might have prevented the attacks. In 1997, the Gore Commission on Aviation Safety and Security recommended dozens of policy changes, including the establishment of federally mandated security procedures that would subject every traveler to a security review before boarding. Four years later, none of the recommendations had been implemented as intended, and most were diminished by lobbying or mired in bureaucratic rule-making.

The debate over intelligence versus policy failure reignites with every disaster. Fundamentally, sound policy depends upon consistent two-way engagement between the distinct worlds of intelligence and policy. This impasse is playing out again at present regarding culpability for America’s ignominious end to the war in Afghanistan. Yet the answer to where culpability lies is rarely, if ever, clear-cut. There is no guarantee that specific policy changes or tactical intelligence warnings could have prevented the 9/11 attacks. Systems of intelligence and policymaking are fundamentally human endeavors, and some degree of failure is inevitable under such conditions. Concomitant policies and overlapping procedures reduce the risk of a catastrophic failure and builds resiliency across American government and society.


The Immediate Response in Afghanistan

Many view the U.S. response to 9/11 in Afghanistan as a successful military operation that went awry over the course of the next two decades. However, those who participated in the initial actions would not characterize it as an invasion. Ambassador Henry Crumpton recalled how the operational speed was driven by an overwhelming sense of urgency from intelligence reports indicating that a second or third wave attack could be imminent. This meant there was no time for a military build-up and invasion in the traditional sense of a significant military action. The CIA officers and Special Forces on the ground initially numbered in the dozens, later growing to a few hundred, but lacked enough support to accomplish America’s strategic goals: to bring those who perpetrated the attacks to justice and prevent Al Qaeda from using Afghanistan as a base.


Ambassador Henry Crumpton on the value of American allies.

Ambassador Crumpton argued that successfully achieving these two goals was really an Afghan victory that demonstrated the value of American allies, ranging from nation-states to tribal warlords. Any American success on the ground was dependent on tribal militias, in addition to support from the U.S. Air Force and Navy. Some have alleged that Afghan militias essentially functioned as mercenaries for the American cause. While many may have had monetary motivations, describing them as mercenaries is an oversimplification that dismisses the struggles faced by Afghan militias. Far more Afghans were motivated by honor and interest in a battle for their homeland and their own families. Relationships were built on the fly, but regardless of how they were forged, trust and confidence provided their foundation.

Going into Afghanistan, it was clear to those involved that Al Qaeda was the principal enemy of the engagement, not the Taliban. The Taliban is not a monolithic hierarchy. It is a network of different tribal factions, all with different agendas. In fact, many Taliban fighters defected to join Afghan militias aligned with the U.S. because they wanted to drive Al Qaeda out of their home regions. Philip Reilly, deputy commander of JAWBREAKER, the first team of Americans to enter Afghanistan in 2001, also noted that just two days before 9/11, Al Qaeda assassinated the leader of the Afghan Northern Alliance. What was intended to be a decapitation strike galvanized the Northern Alliance and made them more receptive to a U.S. alliance.

Remembering the success in Afghanistan after 9/11 as an Afghan victory also helps to understand the quick collapse of the Afghan government in 2021. As retired General Gene Renaurt remembered, the collapse of the Taliban in 2001 also unfolded much more rapidly than anyone in the U.S. expected. Both shocks of surprise arose from the misapplication of American expectations on Afghan realities. Afghans are engaged in a generational struggle for their lives and their homes. American interests were merely ancillary to that struggle. The notion that Afghans are not fighting against the Taliban is just as incorrect today as it was twenty years ago. Absent U.S. support, their challenge is much greater, but it is no less existential.


The Impact on American Society

Many have said that 9/11 marked the end of American innocence. As New York Times correspondent David Sanger put it, when the North Tower was struck at 8:46 am, we believed that it must have been an accident. When the South Tower was struck 17 minutes later, we were never willing to believe again that something could be an accident. 9/11 has greatly contributed to American cynicism, but we cannot say that it is the sole source. Steve Kern, who worked in the North Tower and survived both the 1993 World Trade Center bombing and the attacks on 9/11, noticed that after the 1993 bombing, all the trash cans around the World Trade Center were removed. Soon after, they disappeared from all of lower Manhattan. A gym bag left under a subway seat was no longer just an inconvenience to a stranger, it could be a direct threat to your life. This is something that other Western societies, like Britain, have long lived with in their own experiences grappling with terrorism. Finding the balance between identifying genuine threats to public safety and managing societal aftershocks of terrorism became one of the great challenges of public policy in the subsequent years.


Reflecting on lessons for those who were born after 9/11.

The immediate aftermath of 9/11 showed how to combat cynicism. Kindness and empathy were abundant in the ensuing days and weeks. Ann Van Hine, who lost her husband on 9/11, recalled that she received hundreds of cards from strangers expressing sympathy in the months after the attacks. Many had no specific address; they had simply seen her husband’s name and hometown in the newspaper and wanted to reach out to send a letter or a gift. Another example is the 500,000 people, coming from every state and around the world, that volunteered at Ground Zero during the recovery efforts. Many of those people now suffer terminal illnesses from that work, with more having died from those illnesses than died in the attacks on 9/11. President Bush’s trip to a mosque six days after 9/11 was also critical to showing that America’s counterterrorism “war” lay not with Islam, but a bastardization of its doctrines propagated by Al Qaeda.

The U.S. will continue to remain vulnerable to the possibility of a few people to doing great harm. It is an unavoidable dynamic of living in free and open societies. The question is how we manage the process of adjusting to living with those threats. Hate crimes against Muslim Americans dramatically increased after 9/11, which undermined the principles of inclusivity and equality central to America’s historical mission. Cultural resilience does not arise from fearing and hating fellow citizens. Brenda Berkman, an FDNY firefighter who responded to the 9/11 attacks, encouraged a different path—listening to a diversity of voices and taking on other people’s experiences in order to learn from them. Deep connections within our nation and across our allies may expand our attack surface, but it also makes us more capable of weathering any challenge and building resilient societies beyond a single nation-state.


The Path Ahead

The day after 9/11, a single plane was allowed to come into America, originating from London and carrying the Chief of MI6, the Deputy Director-General of MI5, and GCHQ’s Director. British intelligence had much to offer on counterterrorism because the Irish Republican Army (IRA) had forced them to improve over the thirty years preceding 9/11. Historian Christopher Andrew argued that, as with climate change, pandemics, and other globalized threats, combatting terrorism requires a long-term perspective. A fundamental problem facing governments and intelligence communities in the twenty-first century is a tendency to take short-term views: they suffer from Historical Attention-Span Deficit Disorder (HASDD), an acronym coined by Andrew. Forging a path ahead on counterterrorism requires correcting HASDD—or Applied History.


Sir David Omand on denying terrorists the ability to captivate the public with fear.

Sir David Omand, former GCHQ Director, stressed that British success against the IRA came from having a clear strategic objective: to deny terrorists what they most seek—the ability to captivate the public with fear. After 9/11, the British further refined this approach into CONTEST, a four-step counterterrorism strategy: preventing people from becoming terrorists, pursuing those seeking to carry out attacks, protecting critical infrastructure, and preparing to respond to any attacks that are successful. The fourth step is necessary because it is impossible to stop every attack and the public must be assured that a response will be in place. Omand’s strategy was built on risk mitigation, not the impossible objective of risk avoidance. The threshold adopted by Tony Blair’s government was maintaining normal life through the management of risk from terror attacks.

On 9/11, elements of that type of preparation were already in place in the United States. John Farmer, former New Jersey Attorney General, recalled that New Jersey had a plan to respond to an attack on Lower Manhattan developed in anticipation of threats to millennium celebrations. When the 9/11 attacks occurred, New Jersey officials were able to quickly begin ferrying first responders to Ground Zero and evacuate victims back to New Jersey. 9/11 also stressed the need for better communication between federal, state, and local officials. The federal government cannot be everywhere at once, and local police and firefighters are often the first to respond to terrorist attacks of any size. Improving those lines of communication through organizations like the National Counterterrorism Center (NCTC) has helped counterterrorism officials better utilize tactical intelligence to disrupt plots over the past twenty years.

Structural changes provide limited improvements if people are unwilling to change their mindsets. There are also broader cultural and philosophical roadblocks to consider. In a panel conversation with Graham Allison, Philip Zelikow noted that, in some ways, the American intelligence community has become too important to foreign policy. Intelligence is the first stop for policymakers when they want to know more about the world. Immediate, on-the-ground intelligence may not capture the caveats, nuance, and historical revelations of an integrated analytical approach. Intelligence must be paired with history, diplomacy, and other disciplines to create a more robust decision-making advantage for policymakers.


Michael Morell on the bright red line between intelligence and policy in America.

Michael Morell concluded that, in America, there is a bright red line between intelligence and policy. Intelligence officers inform policymakers, but they do not demand action. As we have seen across the Atlantic, this is not the only way of operating. The British system has always been much more fluid, and in many ways, covert intelligence operations by the U.S. drove policy decisions after 9/11, not the other way around. Finding a balance between the two extremes is not a simple process. As Philip Zelikow envisions it, the IC should function as a scout and navigator for policymakers, not as an alarmist with a role limited to strategic warning. Much like the alliances formed in Afghanistan the days after 9/11, it requires policymakers and intelligence officials to have relationships based on trust and confidence.

Some of the principles from America’s post-9/11 strategy are relevant to a major challenge facing our country twenty years later: the return of great power competition, especially with China. In the immediate years after 9/11, the U.S. was calling for China to be a “responsible stakeholder” on the global stage. Today, it is hard to find anyone on Capitol Hill that holds that view. But few there are willing to ask truly difficult questions about what China’s rise means for American interests: Will the world be less stable? Will America be less prosperous? The IC should help policymakers answer these questions, not simply predict when China might “overtake” the U.S. in any number of fields. Much like with counterterrorism, success starts with a clear strategic objective focused on empowering decision-making to shape outcomes.



Philip Zelikow encouraging intelligence agencies to “work possibilities, not predictions.”

9/11 will always be a source of grief and discomfort for those who experienced terror that day, but that does not have to be the only legacy. 9/11 offers many lessons on the role of cultural resilience and empathy in facing down threats of terror. It also shows us that policy and intelligence must work together to shape outcomes in favor of American interests, not simply respond to the world as it is or predict where the next threat might come from. Zelikow encouraged intelligence agencies to “work possibilities, not predictions.” That is to say, to provide scenarios and context that help shape resiliant and flexible policies, responsive to changing conditions and facts.

As a young nation in the arc of global civilization, the U.S. does not always know its history.

Reflecting on the past can help us better understand what we need to do to contront today’s challenges and avoid future catastrophes. Twenty years after 9/11, America has a chance to reevaluate what it wants to achieve. The path we choose should incorporate all that we have learned.

Paul Kolbe, Belfer Center Intelligence Project Director, former CIA Senior Executive

Calder Walton, Belfer Center Intelligence Project Director of Research

Natalia Angel, Belfer Center Intelligence Project Coordinator 

Sean Power, Belfer Center Intelligence Project Research Assistant

Michael Miner, Belfer Center Intelligence Project Associate


Watch Full Sessions

Welcome and Opening Remarks »
Paul Kolbe

Keynote »
Philip Zelikow

Session One: The Day of the Attack: 20 Years Ago »
Paul Kolbe (Moderator)
Michael Morell
James Clapper
David Sanger

Beginning with national security leaders serving at the time of the attack, the moderator explored professional perspectives on what happened the day of September 11, where panelists were serving that Tuesday morning, and their first thoughts and actions on what to do in response in the immediacy of an unprecedented crisis. 

Session Two: The Response: Government Reactions Following 9/11 »
Rolf Mowatt-Larssen (Moderator)
Ambassador Henry Crumpton
General (Ret) Gene Renuart
John Farmer

This panel included policymakers, military personnel, and intelligence officers who led the response to 9/11 in the subsequent weeks, months, and years following the day of the attacks. The moderator unpacked key decision-points and developments related to government responses in an emerging Global War on Terrorism. 

Lunch Conversation - A View from the Ground – The Response in Afghanistan »
Natalie Colbert (Moderator)
Phil Reilly
Mike Hurley

Recollections of those in first wave of the ground response into Afghanistan. The Taliban collapsed under U.S. ground and air pressure in 2001, with a miniscule U.S. footprint, just about as fast as the Afghan govt and army collapsed in 2021. Why? How? And what does it mean for today? 

Session Three: The Impact: Personal and Societal »
Michael Miner (Moderator)
9/11 Family Group
Brenda Berkman
Ann Van Hine
Steve Kern

This panel included individuals personally impacted by the attacks or during service in the aftermath. The moderator explored how this unprecedented event shaped American society. Questions and discussion offered an opportunity to hear personal reflections from those affected and how this moment changed lives forever. 

Session Four: Twenty Years Later - 9/11 History »
Calder Walton (Moderator)
David Omand
Philip Zelikow
Christopher Andrew  

With the passage of two decades, historians now have a longer view of the impact of 9/11 on governments and societies around the world. Moderated by Calder Walton, this panel of historians and political scientists grappled with the historical implications of 9/11 and what we have learned over the past twenty years. 

Session Five: The Future - Applying 9/11 History »
Graham Allison (Moderator)
Michael Morell
Amb Henry Crumpton
Phil Zelikow

A driving question for current practitioners is how we learn from the lessons of history and adapt to meet modern and future challenges. This panel featured currently serving policymakers and their reflections on how 9/11 shaped their worldview and decision-making for a world dramatically different than September 10, 2001. Digital/cyber/tech - what are the possible future 9/11’s, how do we spot them, and how do we prevent them. 

For more information on this publication: Belfer Communications Office
For Academic Citation: Power, Sean , Calder Walton and Michael Miner . “Report - 9/11: Intelligence and National Security Twenty Years Later.” Belfer Center for Science and International Affairs, Harvard Kennedy School, September 23, 2021.