MARY LOUISE KELLY, HOST:

U.S. forces are now over 90% out of Afghanistan. That's according to a statement this week from U.S. Central Command. So it's looking like the U.S. will easily hit President Biden's goal - complete withdrawal from that country by September 11. But as U.S. forces pull out, the Taliban has been sweeping in, seizing district after district, one by one, mostly in the northeast of the country, which prompts a question - what about big cities? What about Kabul? Will the Afghan government hold? I put that question to Ryan Crocker, former U.S. ambassador to Afghanistan, yesterday.

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RYAN CROCKER: I think that it's entirely possible that the government can hold if the Taliban decides not to pursue an all-out offensive. It isn't the government that's going to be making that decision. It isn't us. It's the Taliban.

KELLY: I want to get some reaction to that from Aaron O'Connell, veteran of both President Obama's National Security Council staff and of the war in Afghanistan. He served with the Marines there. He's now a history professor at the University of Texas at Austin. Aaron O'Connell, welcome back.

AARON O'CONNELL: Thanks, Mary Louise. Great to be with you.

KELLY: So, Ambassador Crocker there saying, the future of Afghanistan is in the hands of the Taliban right now. We got to wait and see what their next move is, which feels to me like a pretty uneasy place to be. What's your reaction?

O'CONNELL: Well, I agree with Ambassador Crocker. I think that the Afghan government can probably hold the four major cities.

KELLY: Just tick off those four cities. That would be Kabul, Kandahar...

O'CONNELL: Mazar-i-Sharif and then over in the west of the country, Herat. So I agree with Ambassador Crocker that if the Afghan government can hold those four cities, then there is a future for the Afghan state. He's right, of course, that this isn't a decision the Afghan government will make, that it depends on the actions of the Taliban. But that's true in all wars. The enemy always gets a vote.

KELLY: But let me push you on this. What gives you confidence that those four cities will hold? The Taliban's taken them before. There's history here.

O'CONNELL: Well, there is. I don't think we are in the same position as in the 1990s, when the Taliban marched into Kabul with significant help from the Pakistani state. Let's be clear about that. I agree that some of the news over the last two months has been alarming, with the Taliban taking some of the northeastern districts and some districts in the west. But that's part of this long competition between the rural and the urban in Afghanistan. So I just don't see the Taliban having the military capacity to march into the cities and, indeed, to hold those cities, which is equally important.

KELLY: I mean - let's stay and draw on your military experience here a little bit more. One major advantage the security forces have is they have an air force. The Taliban doesn't.

O'CONNELL: That's a real advantage. And one of the critical elements for the future of the Afghan state will be whether or not they can keep that air force flying. And if they are sustained, that will give the Afghan government a real advantage in being able to survey the landscape, understand where attacks are coming from and respond to them.

KELLY: You advised General Petraeus when he was commander there. And I'm thinking of the famous Petraeus question - tell me how this ends. Without wanting to ask you to predict what is unknowable, of course, you know, five years from now, when I call you back, what's the range of possibilities for where you think Afghanistan might be?

O'CONNELL: Well, the optimistic scenario would be that the Kabul government holds and actually maintains a monopoly on force inside the four major cities. If that happens, there will be the infrastructure for U.S. development aid and diplomatic relations and schooling and water and sanitation. And those kinds of things will continue to help portions of Afghanistan - in the major cities and around them - to be safe from the Taliban and, indeed, to reject the Islamist narratives that have such appeal in the rural areas. That's probably the best-case scenario.

KELLY: What's the worst case?

O'CONNELL: The worst-case scenario is the fall of the Kabul government. That is possible. I think it's unlikely, but it's possible. And then Afghanistan returns to being so ungoverned that it's possible that transnational terrorist networks - ISIS, al-Qaida - that they then reestablish control over a sufficient amount of area to plan attacks.

KELLY: I don't want to dwell on the worst-case scenario, but that feels like an awfully depressing place to be after 20 years, after trillions of dollars spent, after so many lives lost, both American and American allies and, of course, many more Afghans.

O'CONNELL: It is depressing to imagine that possible scenario. I think why I remain more optimistic than some is that I know that the Taliban is deeply unpopular in the major urban centers of the country. Those urban centers, over the last 20 years, have raised an entire generation of Afghans who are educated. They want jobs. They want contact with the United States. If those areas remain protected, then those cities will remain a magnet for people trying to escape the rural areas and the harsh Islamist rule of the Taliban.

KELLY: If I'm hearing you right, you're saying that wherever we may fall at that extreme - best-case scenario, worst-case scenario or somewhere in between - you're arguing that there is some lasting good, that having U.S. engagement in Afghanistan for two decades now has not been a waste.

O'CONNELL: It certainly has not been a waste, by a number of measures. First of all, there is no transnational terrorist network that can attack the United States from Afghanistan now, and I do not think there will be. Second of all, there is an entire generation of Afghans who have been raised with education, including women being allowed in the schools again, and have become technically proficient and in search of modern jobs. Third, the life expectancy of the Afghan people has increased by a decade, thanks to U.S. and international health assistance. All of those things are major advances that we should be proud of. The fact that our influence is only welcomed and, indeed, enhanced in the urban areas is not somehow proof that 20 years of U.S. engagement in Afghanistan has been a waste.

KELLY: That's Aaron O'Connell, former member of President Obama's national security staff, editor of the book "Our Latest Longest War: Losing Hearts And Minds In Afghanistan."

Aaron O'Connell, thank you.

O'CONNELL: Thanks, Mary Louise. Great to talk to you. Transcript provided by NPR, Copyright NPR.