RENEE MONTAGNE, HOST:
And if you were to look at a map of territory held by Islamic State fighters in Iraq and Syria in 2015, it would show that the terrorist group lost ground. ISIS was run out of areas near the Turkish border, and it lost most of the Iraqi city of Sinjar. Yet foreign fighters continue to join ISIS. NPR's counterterrorism correspondent Dina Temple-Raston explains why.
DINA TEMPLE-RASTON, BYLINE: Here's a way to understand how ISIS continues to attract followers in the face of defeat. It claims its setbacks are the fulfillment of prophecy.
RICHARD BARRETT: And in the way that they see themselves as people who are fighting for God's cause, then, you know, death is not such a bad thing quite frankly. So in a way, death is as much a reward as success.
TEMPLE-RASTON: Richard Barrett of the Soufan Group says if you suspend belief for a moment and believe that death is as much a reward as success, then by extension, that means defeat, large and small, are acceptable as well. He says ISIS argues that battlefield losses in Syria and Iraq are not only preordained, they're temporary.
BARRETT: So if they lose Mosul even, maybe even if they lose Raqqa, they won't disappear completely. They'll still be evident in Iraq and Syria, and they will believe that in due course they will get them back and more.
TEMPLE-RASTON: The group points out the Prophet Muhammad suffered ups and downs in his quest to establish a state, and the modern-day caliph, Abu Bakr al-Baghdadi, will experience them, too. So that's one reason why ISIS has proven so resilient and has kept its followers.
SEAMUS HUGHES: You know, I used to do community engagement, and we would to talk about the reasons why people would want to go to Syria and...
TEMPLE-RASTON: That's Seamus Hughes. He's the co-director of the program on extremism at George Washington University.
HUGHES: And you can acknowledge the fact that there are horrible human rights abuses, and there's starvation, and you want to do something, and ISIS provides - at least it says it provides that outlet to do something.
TEMPLE-RASTON: And that's a start. But he thinks that the motivations for joining ISIS have shifted in recent months. Now it isn't just about battling perceived atrocities in Syria. Instead, he says following the group has become some sort of religious obligation. ISIS aims to be at the forefront of an end-of-days battle. It's pitting its fighters against the West to establish a Muslim homeland. And that's the second reason the group has had such staying power. It hasn't asked its followers to wait to make history. It says it's establishing a caliphate now.
WILL MCCANTS: Most jihadists, Sunni jihadists, put off the return of the Islamic Empire until the final stage of the conflict.
TEMPLE-RASTON: Will McCants studies terrorism at the Brookings Institution. And when he says most jihadists, he means al-Qaida. Al-Qaida leaders have always said the caliphate would have to wait. But, ISIS says its followers don't have to.
MCCANTS: The ISIS guys argue that the time for the return of the empire has come now. And they have been good at promoting their symbols, promoting their brand and selling young men and women on the idea that God's kingdom on earth has returned.
TEMPLE-RASTON: That's why ISIS followers are willing to overlook the group's setbacks and its shortcomings. They think they've signed up for eternal salvation.
MCCANTS: And I think as the Islamic State loses territory in Syria and Iraq, you'll see a lot of the foreign fighters begin to go to some of their other strongholds in the region.
TEMPLE-RASTON: Strongholds like Libya where ISIS is establishing yet another beachhead, last week, Defense Secretary Ash Carter said he was aware of the problem. He said the U.S. and its allies were in the process of preparing options to prevent ISIS from establishing training sites there. Dina Temple-Raston, NPR News. Transcript provided by NPR, Copyright NPR.