And today president obama held a meeting in the situation room to get an update on the investigation. The heads of the fbi and cia were there among others. Which leads us to abc's chief global affairs... See More
And today president obama held a meeting in the situation room to get an update on the investigation. The heads of the fbi and cia were there among others. Which leads us to abc's chief global affairs correspondent, martha raddatz. Martha, thanks for coming in. We appreciate it. Let's talk about the older brother's trip to russia. We know there are islamic militants in this part of russia, but do these people have history of attacking america? Not the chechens. They have no history of attacking the what investigators will want to find out is whether he went to some sort of training camp, some radical training camp that did have a beef with america. Who funded him? If he had any sort of extra funding. Did he learn how to build those bombs here, or did he build them on the internet? And they will interview everybody they possibly can to se those dark months led. If they rule out some sort of foreign plot, and that's a big if at this point, it would make these two brothers, assuming they're proven to be guilty, it would make them lone wolf, which as I understand it, has been keeping up national security officials in the middle of the night for years now. Yes, because if you have one lone wolf who they believe probably convinced his brother to be another one, then you don't know where the rest of them are. What will inspire them, how might get radicalized. That's a nightmare scenario. Thank you, martha. I want to switch gears back
This transcript has been automatically generated and may not be 100% accurate.