Harvard Kennedy School faculty members Meghan O’Sullivan, Ash Carter, and Eric Rosenbach all have deep national security experience, serving U.S. presidents of both parties during contentious wars and counter-terrorism operations since 9/11.

Reflecting this week on the 20-year American war in Afghanistan, they aired sometimes contrasting perspectives on what went wrong and what policy lessons the United States should learn. And their views did not line up neatly along partisan lines.

HKS Dean Douglas Elmendorf hosted two conversations in one day on the lessons from Afghanistan. At an afternoon event—the first in a series of three Dean’s Discussions on the topic of Afghanistan—he introduced O’Sullivan, the Jeane Kirkpatrick Professor of International Relations, who served in the Bush Administration in the years after the Sept. 11 terror attacks, and Rosenbach, a public policy lecturer and former Army intelligence officer who later held senior Pentagon positions. The event was moderated by Sarah Wald, the dean’s senior policy advisor and chief of staff.

Also joining that Dean’s Discussion was Farah Pandith, a long-time HKS senior fellow who brought an American diplomatic viewpoint as well as a Muslim-American perspective. She served in three U.S. administrations and was the first special representative to Muslim communities under Obama.
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Then, in the evening, Elmendorf hosted a John F. Kennedy Jr. Forum featuring Carter, the former secretary of defense and now Belfer Professor of Technology and Global Affairs and director of the Belfer Center for Science and International Affairs.

Carter, who served in Democratic President Obama’s Cabinet, and O’Sullivan, who served Republican President George W. Bush as deputy national security advisor for Iraq and Afghanistan, both argued that the United States should have kept a limited military force in Afghanistan rather than withdraw completely, as happened in August after the Taliban insurgents overran the capital, Kabul, and seized control.
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Carter said that in recent years the United States was in a position where a “relatively small number of U.S. forces was able to keep the lid on in Afghanistan. That’s a lot, for a small price….. It was not an endless war. It was, in my view, an endless presence. We were not going to leave any time soon. That’s as good as it gets.”

“I know I was in a minority in believing this,” Carter added. “Most of my fellow Americans did not believe in it. And so they abandoned that mission.... It’s a good old-fashioned bipartisan American mistake.”

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“It was not an endless war. It was, in my view, an endless presence. We were not going to leave any time soon. That’s as good as it gets.”
Ash Carter

At the Dean's Discussion, O’Sullivan speculated that the Biden administration may have framed its policy deliberations in a way that contributed to what was, in her view, a deeply flawed outcome. She suggested policymakers might have been focused more on "how to end the war" than on "how to protect ongoing American interests in Afghanistan;" she said asking the latter question could have led to very different options and outcomes. O'Sullivan argued that a better option than complete withdrawal would have been an ongoing, limited military commitment to underpin the Afghan government, support the Afghan security forces, and prevent terrorist groups from reconstituting.

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“One lesson learned would be our belief that we can fix every problem, right? So to have a little bit more humility over what can be achieved.”
Meghan O'Sullivan

Rosenbach, the Belfer Center co-director who was an Army intelligence officer before earning a Kennedy School degree and then serving on the Senate Intelligence Committee after 9/11, offered a different view. He reminded the audience that U.S. forces were not in combat with the Taliban only because of the Doha Agreement, negotiated by the Trump Administration in early 2020. That was premised on the U.S. withdrawing by May 2021, which Biden stretched to August, even as the Taliban were advancing steadily.

“You leave 6,000 troops there, and here’s what happens. They get attacked. Guess what? We have to send more troops. We have to bomb the Taliban, who attacked us. We make mistakes, more Afghans die…. You don’t get out of there,” Rosenbach said. “This small footprint thing; when you do the scenario planning, it’s not a real option.”

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“You leave 6,000 troops there, and here’s what happens. They get attacked.... We have to bomb the Taliban, who attacked us.... This small footprint thing; when you do the scenario planning, it’s not a real option.”
Eric Rosenbach

Pandith focused on unsettling global strategic issues; she stressed that one of the casualties of 9/11 was failing to understand what Osama bin Laden actually unleashed. “It was the destabilization of our relations with Muslims around the world.” That in turn fueled extremism on both sides and heightened fear of “the other,” she said. “I can draw a straight line between 9/11 and 1/6,” referring to the attack on the U.S. Capitol by Trump supporters.

She also challenged Rosenbach’s suggestion that the Taliban might prove more rational in their second stint in power. “They believe there's one way of being a Muslim and anybody who isn't like that needs to be beheaded,” she said. In shaping the U.S. policy response, “we have to ask ourselves, what are we ready to do? What are our red lines?”

There was agreement on some aspects of the war—and on some lessons.  Carter, O’Sullivan, and Rosenbach all acknowledged the danger of allowing the military to trap civilian policymakers by leaking information to the media that leaves political leaders little option but to adopt a harder stance or risk being seen as weak.

Rosenbach, who described himself as “not that partisan,” gave credit to Biden for “biting the bullet” and taking the political hit for finally getting U.S. troops out of Afghanistan altogether, even though he said the execution of the departure was botched. His lesson: “Don’t forget what it is we are trying to do—not the creep of all the wonderful things you might be able to do.”

Another lesson was  the danger of overestimating what U.S. power can achieve, or as O’Sullivan put it, "One lesson learned would be our our belief that we can fix every problem, right? So to have a little bit more humility over what can be achieved."

Said Carter: “For those of us in national security, we have to be more parsimonious about what we take on, and we have to explain very carefully why it’s good for the American citizen.”

Two more Kennedy School Dean's Discussions on Afghanistan are scheduled this term: Nov. 1, on what's next for Afghanistan and its people, with Ricardo Hausmann, Asim Khwaja, and Zoe Marks; and Nov. 8, on international relations with Graham Allison, Kathryn Sikkink, and Stephen Walt.