AUDIE CORNISH, Host:
Steve, I want to begin with you. How do you feel that the strike on the Pentagon changed the military? Because obviously, this has had an effect on them - maybe even different from what happened in New York.
STEVE COLL: And certainly, the mobilization and spending and doctrine and experiences that the Pentagon has led since then is really still defining - as to what military posture the United States has, and what capabilities it has, in the world today.
CORNISH: Tom Gjelten, how would you compare the differences before and after the attacks, in terms of the culture of the military?
TOM GJELTEN: I remember the next day. I came back to the Pentagon where I was - where I had my, you know, that was my assignment. The building smelled of smoke. All the military personnel were dressed in battle dress. And from that moment on, it was really a changed place, because there was instantly a sense that the United States had to respond to these attacks, identify the perpetrators, take action against them. So it was really a call to action at the military that began within hours of the attack.
CORNISH: Steve, you wrote a book, called "Ghost Wars," about the covert wars by the U.S. in Afghanistan before 9/11. Obviously, Afghanistan - we had troops in Afghanistan by winter of that year. Talk about how that legacy affected the invasion that took place weeks after the attacks on September 11.
COLL: First, set the stage for a bombing campaign against the Taliban, after the Taliban refused to yield al-Qaida and bin Laden. And then eventually, for the Taliban's overthrow by military action. It was a very swift campaign. It was made more effective by these existing networks that the United States had quietly built up in the years before 9/11. But it was also a reckoning, in some respects, for the United States in Afghanistan because we had been there throughout the 1980s, arming and supporting Islamist militias, some of them with anti-American agendas. That had created a...
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CORNISH: Tom, I was wondering if you could talk to me a little bit about what the annual tradition has been at the Pentagon for celebrating the anniversary - or memorializing the anniversary of the attacks.
GJELTEN: And first, the building was rebuilt. And then a memorial was put in place. And every year on 9/11, on the anniversary, there have been speeches and ceremony commemorating that day. Transcript provided by NPR, Copyright NPR.