SCOTT SIMON, HOST:
Secretary of State Rex Tillerson calls the fall of Raqqa to Syrian Kurdish forces backed by the U.S. a critical milestone in the global fight against ISIS. But he also says our work is far from over. Raqqa is in ruins after the defeat of ISIS. The city was their self-declared capital. Bruce Hoffman is author of the book "Inside Terrorism" and director of the security studies program at Georgetown University. He joins us in our studios. Professor, thanks so much for being with us.
BRUCE HOFFMAN: You're welcome.
SIMON: And how big a blow is this to ISIS?
HOFFMAN: It's a significant setback. It certainly has deprived them of the place that was once their capital. But I think the challenge is that there's still 6,000 to 10,000 ISIS fighters that control about 4,000 square miles of the border between Iraq and Syria. And I think more significantly, while we've been hammering ISIS in Iraq and Syria, it's actually spread. There's about eight ISIS branches in some 18 countries throughout the world right now.
SIMON: Is that the nature of a - do we call it a movement, a group? - an organization like ISIS, that in a way the more amorphous they are - if they're not trying to hold on to territory - the more they can threaten to strike over a larger area.
HOFFMAN: That's precisely the challenge. You have to fight them on two levels. You have to fight them conventionally and seize their physical sanctuaries and safe havens. You also have to counter their ideology, their residence, their appeal to attract recruits. And I would say that certainly is part of ISIS' falling star. Its cachet has been damaged. But at the same time, we know from ISIS propaganda - which up until the summer was calling on followers, would-be foreign fighters to come help build a state - now their propaganda has pivoted on, help us exact revenge and retaliate for the destruction and loss of our state. And that will be a significant motivation going forward.
SIMON: We've been speaking, obviously, this week about the four U.S. Special Forces soldiers who were killed in operations against ISIS in Niger. I'd wager a lot of Americans were surprised to hear that U.S. forces were actively operating in that area. What is the reach of ISIS now?
HOFFMAN: This, I think, is one of the challenges we face, is that ISIS hasn't stood by idly in the past three years since the coalition came together and resolved to expel it from Iraq and defeat it in Syria. Instead, it adopted a strategy to ensure its longevity. And that, basically, entailed the cultivation of branches throughout North Africa, the Sahel, the Middle East, South Asia, Southeast Asia as well. And much like al-Qaida did over a decade ago, this has been precisely their motivation, in essence, and their solution to be able to carry on the struggle even as they face territorial setbacks and military losses.
SIMON: The way you explain it, to one degree, the smaller they are, the more mobile they are and the more long-lasting they can be.
HOFFMAN: The conflict or the challenge just shifts to a different level. Terrorist groups are almost like water. They flow to where they feel that they have some release or some escape. And what that entails is that we have to constantly adjust and adapt our own strategies and our own countermeasures as the terrorist groups evolve and change to compensate or to overcome for even some of our most significant tactical successes on the ground.
SIMON: In the limited time we have left, one bit of advice you'd give.
HOFFMAN: Continue to take down the sanctuaries and safe havens. That's, I think, the most important first step because that's part of the appeal of these groups, that it's not just an idea. They have a physical presence. And as long as we reduce that, we'll make progress in this struggle.
SIMON: Thanks very much, Bruce Hoffman, director of security studies program at Georgetown University. Nice to talk to you again.
HOFFMAN: Thank you.
SIMON: And tomorrow on Weekend Edition Sunday, we'll speak with a reporter who's been on the ground in Raqqa. She's seen firsthand whatever's left of the city. That's tomorrow morning on Weekend Edition Sunday. Transcript provided by NPR, Copyright NPR.