Remembering 9/11

20 Years Later

Blind or Confused:
The Impact of 9/11 and Its Aftermath on Risk

September 22, 2021 | Professor Nathan Freier

In a defense and military security context, the United States has at times been “risk-blind” and, at others, “risk-confused” over the last two decades.1 These conditions likely predate the 9/11 attacks. But 9/11, the post-9/11 period, and the United States’ current struggle to adapt to post-primacy indicate defense and military leadership have yet to employ (or maybe are just now employing) risk effectively in their most important strategic decisions.2 If and when leadership begins to routinize risk-informed strategy development, the United States will also likely begin to avoid the wide, unpredictable, costly, and ineffective swings in priorities that have plagued US strategy over the last 20 years.

Continue reading: Blind or Confused: The Impact of 9/11 and Its Aftermath on Risk

Twenty Years after 9/11: The US Army at a Crossroads

September 9, 2021   |  Colonel George Shatzer


No retrospective on the September 11 attacks can escape the bleak pall cast by the tragic events unfolding in Afghanistan today. Despite the enormous financial investment in the country and the grim human costs borne by the United States, its allies, and Afghans over the past 20 years, the US and NATO military missions have ended in ragged, ignominious failure. The question of how well these operations protected the United States and the world from Islamist terrorism remain open. But there is no doubt that the other stated purpose of creating a functioning, friendly, Afghan government and effective security forces that can prevent the reemergence of terrorism from within the country is now forfeit.

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The Lessons of 9/11 for Defense Planning

September 8, 2021  |  Dr. Roger Cliff

On the morning of September 11, 2001, I was working at the Pentagon in the office of the deputy assistant secretary of defense for strategy. The DoD was preparing to issue a report documenting the findings of the 2001 Quadrennial Defense Review, an eight-month-long, comprehensive review of the department’s plans and programs. The theme of the report was the need to “transform” the armed forces of the United States to ensure they would continue to hold a dominant advantage over any potential, future challenger. Although never named in the report, the challenger DoD leaders had in mind was China.

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9/11, Post-Primacy, and
Defense Strategy Development

September 7, 2021   |   Professor Nathan Freier

INTRODUCTION: LAST FEW HOURS OF UNRIVALED PRIMACY September 2001 was Quadrennial Defense Review (QDR) and Defense Planning Guidance (DPG) season in the Pentagon. The QDR was the Bush-Rumsfeld DoD’s first crack at publicly reshaping the post–Cold War military.1 The DPG was the classified instrument by which the Rumsfeld team was to reprioritize military planning and resources to meet the QDR’s public-facing, transformational vision.2 Thousands of civilian and military staffers entered the Pentagon through the old Metro entrance on September 11, 2001, to analyze, contest, or operationalize every word, phrase, graph, and figure in the QDR and DPG.

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9/11, Latin America, and the
Impermanence of Strategic Concepts

September 7, 2021  |  Dr. R. Evan Ellis

On September 11, 2001, then US President George W. Bush had just completed a historic summit with his Mexican counterpart, Vicente Fox, the week prior. The interaction built on the “special friendship” between the two nations and the intertwined commercial, security, and other strategic interests binding the United States and Mexico.1 This relationship had deepened considerably in the seven years since the two nations, along with Canada, had signed the North American Free Trade Agreement. For those of us emphasizing the importance of the US bond with the people of its hemisphere, there was hope the new post–Cold War order would finally allow Mexico, Latin America, and the Caribbean to receive their due with respect to US attention and partnership.

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9/11 and the Army Reserve: The Strategic Shift

August 31, 2021  |  Colonel Matthew W. Lawrence

Military members stand waiting for the the 2019 Pentagon September 11 Observance to begin at the Pentagon 9/11 Memorial in Arlington, Va., Sept. 11, 2019. President of the United States, Hon. Donald J. Trump, Chairman of the Joint Chiefs of Staff, Gen. Joseph F. Dunford, Jr., and Secretary of Defense, Hon. Mark T. Esper, hosted the ceremony. (U.S. Army photo by Sgt. Dana Clarke)

The 9/11 attacks’ effects on the United States and its foreign policies cannot be understated. The United States, in essence, lost its innocence that day and has never been the same. The attacks spurred changes in the way the United States handles national security, secures air transportation, and shares intelligence. The attacks also resulted in, directly and indirectly, two major armed conflicts that lasted the next two decades. These conflicts served as the catalyst for the most significant strategic shift in the US Army Reserve’s history—the organization’s transformation from a strategic force to an operational one. This transformation was not merely policy; it was ingrained in the organizational spirit as well.

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“Après Nous, le Déluge”

August 31, 2021  |  Dr. Chris Mason

The Taliban have retaken control of Afghanistan. The quixotic, United States-led, 20-year nation-building project in Afghanistan is over. “I . . . don’t think anyone thought Afghanistan would turn so badly so quick,” a US official is quoted as saying recently.1 If that is true, then no one read my book, The Strategic Lessons Unlearned from Vietnam, Iraq, and Afghanistan: Why the Afghan National Security Forces Will Not Hold, which in fact predicted these events in detail six years ago.2 As I watched yet another foreign country imagined by the United States collapse and another foreign military built by the US Army disintegrate, I often thought of Paul Kattenberg, the State Department officer who tried unsuccessfully to alter the trajectory of American policy in Vietnam.3 By the early 1960s, Kattenberg had worked in and on Vietnam for more than a decade and knew the country better than anyone else in the United States.4 His expert advice was spurned by Chairman of the Joint Chiefs of Staff General Maxwell Taylor, Secretary of Defense Robert McNamara, Secretary of State Dean Rusk, and  Ambassador Frederick Nolting, none of whom had spent more than a few days in Vietnam and knew virtually nothing about the country. Kattenberg was marginalized for his efforts.

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“Never Forget”:
9/11 Then and Now—Thoughts on Readiness

August 31, 2021  | Dr. Sarah Lohmann

Members of the Joint Service Honor Guard participate at the Pentagon September 11 Observance ceremony at the Pentagon Memorial, Washington, D.C., Sept. 11, 2019. (DoD photo by U.S. Army Staff Sgt. Nicole Mejia)

On the morning of September 11, 2001, I stopped by the post office on my way to the newsroom of the Washington, DC–based newspaper where I worked as an editorial writer. I wanted to mail a postcard of the World Trade Center, where I had just been for an interview with a foreign dignitary a few days before. 

“This no longer exists,” the postal employee said as he looked at the postcard I had shoved into his hand. “Word is, next plane is headed for the Capitol,” he said, cranking up the radio.

A few short minutes later, I watched plumes of smoke from the Pentagon clog up the horizon as I drove by on the freeway. Cars were parking on the side of the road, everyone trying to call loved ones. The city was mass  pandemonium as Capitol Hill workers abandoned cars and ran, observing the warning the Capitol was to be evacuated. 

Continue reading: “Never Forget”: 9/11 Then and Now—Thoughts on Readiness

Twenty Years after 9/11:
Implications for US Policy in the Middle East

August 31, 2021  |  Dr. Christopher J. Bolan

190911-N-YG104-0003 ARLINGTON, Va. (Sept. 11, 2019) An American flag is unfurled over the west side of the Pentagon at sunrise in Washington, D.C., Sept. 11, 2019. During the Sept. 11, 2001 attacks 184 people were killed at the Pentagon. (U.S. Navy photo by Mass Communication Specialist 1st Class Sarah Villegas)
The September 11 attacks represented a major strategic shock to US foreign policy in the Middle East. Whereas much of US foreign policy during the Cold War understandably focused on the global threats posed by the Soviet Union and China, these attacks orchestrated by Osama bin Laden from a hideout in Afghanistan propelled both the Middle East and terrorism to the center stage of US foreign policy making. The subsequent Afghanistan War and Iraq War were some of the longest (and least satisfying) military campaigns in US history. After 20 years of military and economic investment in the region, US politicians, strategists, and citizens alike are now questioning the return on that investment and calling for a reorientation of US foreign policy away from terrorism in the Middle East and toward great-power competition with Russia and China.1

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9/11 and the Ethics of Fear:
Maintaining the High Ground in the Face of Uncertainty

August 31, 2021  |  Dr. C. Anthony Pfaff


The coordinated terrorist attacks on 9/11 took the lives of almost 3,000 people, destroyed $55 billion worth of infrastructure, and caused $123 billion in other economic impact.1 Perhaps just as tragically, the attacks destroyed Americans’ sense of security. Though the United States had experienced terrorist attacks before, the scale of the September 11 attacks transformed acts previously considered to be criminal to acts of war. Indeed, the Pearl Harbor attack, which led to the United States’ direct involvement in World War II, resulted in 2,403 persons killed, of whom 68 were civilians.2 When compared to that attack, 9/11 seemed to be the start of a new kind of threat for which prior counterterrorism efforts were inadequate.

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The Best-Laid Plans Upended

August 27, 2021 | Dr. John R. Deni

Pentagon Memorial dedication ceremony

The American national security establishment is shifting from nation building to addressing the challenge of rising great powers, from a near obsession with the United States Central Command geographic area of responsibility to an emphasis on the Indo-Asia-Pacific region. Sound familiar? This shift both reflects the trajectory of US policy today and echoes where the United States wanted to go 20 years ago, before the September 11 attacks derailed Washington’s intentions. As the United States embarks on a new national security approach, the nation would do well to remember events have a way of undermining the best-laid plans and strategies. 

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Further Reading: Memorials

Further Reading: Resources

NDU’s Institute for National Strategic Studies:

LESSONS ENCOUNTERED: Learning from the Long War
September 2015; Edited by Richard D. Hooker, Jr., and Joseph J. Collins

US Naval War College’s Center on Irregular Warfare and Armed Groups

“Defeating ISIS and Al-Qaeda on the Ideological Battlefield: The Case for the Corporation Against Ideological Violence"
August 2018, Michael W.S. Ryan

National Intelligence University

“After the Wars: International Lessons from the U.S. Wars in Iraq and Afghanistan"
September 2021, edited by John A. Gentry and William M. Nolte

US National Strategy for Counterterrorism:

National Strategy for Counterterrorism of the United States of America, October 2018

The 9/11 Commission Report

“Final Report of the National Commission on Terrorist Attacks Upon the United States"

Further Reading: Commentary

A View from the CT Foxhole:

Admiral (Retired) William H. McRaven, Former Commander, U.S. Special Operations Command, and Nicholas Rasmussen, Former National Counterterrorism Center Director, Reflect on the Usama bin Ladin RaidAPRIL/MAY 2021, VOLUME 14, ISSUE 4; AUDREY ALEXANDER

Terrorism and Counterterrorism Challenges for the Biden Administration

USMA’s Combating Terror Center: JANUARY 2021, VOLUME 14, ISSUE 1; Authors: BRUCE HOFFMAN, JACOB WARE

Further Reading: From SSI Partners

World Trade Center, New York City

Flight 93 National Memorial, Pennsylvania