The ability of Isis terrorists to recruit Americans into the jihadist army's fold. As ABC's chief invest gative correspondent Brian Ross tells us, one American city has become a top target. Reporter:... See More
The ability of Isis terrorists to recruit Americans into the jihadist army's fold. As ABC's chief invest gative correspondent Brian Ross tells us, one American city has become a top target. Reporter: This midwest city is reeling from what's happening in the mideast. Of the estimated 100 young American men fighting with Syria's brutal terror groups, authorities say almost a dozen of them have been recruited from a pipeline from the Minneapolis area. They're recruiting friends and friends and friends. It's becoming a bigger network of how to recruit young men. Reporter: Community leaders describe them as vulnerable young men who have become angry, often after run-ins with the law. Like Doug McCain who was reported killed this week in Syria. A a student in suburban Minneapolis in the late 1990s, he became friends with troy castigar, who also became a jihadist with the Al Qaeda affiliate in Somalia. This is the real disneyland. Reporter: Castigar was later killed in battle, like his friend, McCain. Authorities say social media is a big part of the recruitment. And surprisingly, Isis uses rap music appeals to get foreign fighters. Despite its otherwise rigid rejection of all things western. Listen to this American voice. ? This goes out to all my soldiers, freedom fighters equalizers ? ? they slaughter us like animals now it's time for the beast to bite 'em ? ? black flags we worldwide Syria to Atlanta ? Reporter: With increasing concern about the threats of American recruits should they return home, the FBI in Minnesota has issued a public plea for held inspect trying to identify them. A lot of times, these individuals are fairly adept at covering their tracks. Reporter: Now the recruitment has expanded to include women, who the group says make effective fighters. This week, one family in the twin cities reported their teenage daughter had gone missing and is now believed to be with Isis in Syria. For "This week," Brian Ross, ABC news, New York. Let's take this on with our experts. John Cohen just stepped down in July as counterterrorism coordinator for the homeland security department. Brad Garrett is a former FBI agent who has worked numerous international terrorism cases. And mubin shaikh is a former jihadist who went on the work with Canada to prevent this kind of thing. They're recruiting like never before. Your concerns? Is it just social media? Why now? Why is this so huge? I think the tease illustrates one of the reasons we're so concerned. They're very sophisticated in their use of social media. They've westernized their message. They're seeking to recruit or inspire westerners and people in -- That rap music was incredible. They have americanized their message. So, we have to be concerned. And we have to take steps to neutralize that. It's not just countering their message. It's understanding why their message is resonating and what we can do in the community to lessen the impact that that message has. Police are a big part of it. But police working with faith leaders, community leaders, social service providers. Mental health professionals. So that as we start identifying kids who may be going down the path of reacting to what their hearing from Isis and from these other groups that we can come together as a community to keep them from carrying out an act of violence. I want to go to you, mubin. You self-radicalized. 20 years ago? 1995. You went to Pakistan. How did this happen? And then you recruited others. What was it about you that was willing to go along with this? I think the same case for many of these individuals. Identity crisis. You don't know. You're trying navigate the space in the west. How Muslim am I supposed to be? How much western am I supposed to be? That will contradict. You go to those that greet you with open arms. You're dealing with angry, young, disenfranchised, or at least feel they're disenfranchised. They might not even be discriminated against. But they'll feel that my people are under attack. And you have vicarious suffering. You start to feel that their suffering is my suffering. Brad jump in here. You've seen this. You know there's a difference between Al Qaeda and Isis. Talk about that. Then once they find these young men or women, what do they do with them? Do they go from computers, they walk into Syria. I know they do sometimes across the Turkish border. How is this organized? There is a grooming period that occurs. Primarily it starts with the recruitment. A very slick multilingual almost hollywood-style videos that promote excitement. Weaponry. Empowerment. All of these things. Revenge. And maybe the most important. Community. We have built a new society. Come to us. No matter where you're from. Canada, the U.S., the Brits. It's like every other radical extremist group, whether it's a cult or otherwise. They narrow the trough. That's all you hear, day in and day out. Eventually, that is your reality. They're so far ahead right now. 10,000 fighters. More than 10,000 fighters. This seems like a lifelong problem for us. Well, if there's any good news, the FBI, the department of homeland security has been working for the last several years with state and local authorities, with fate organizations around the country, with community groups. Interestingly enough, a big part of our national strategy is locally focused. Supporting efforts at the community level to empower the communities. To better recognize. Better detect the individuals that may be potentially a threat. To work together to deal with that. Mubin, very quickly. Will it work is this can we stop it? It can work. We can do something. But, the horse has bolted from the farm. Okay. Thank you very much to all of you.
This transcript has been automatically generated and may not be 100% accurate.