BLITZER: The U.S. will soon get its first look at the crash debris from that Russian Metrojet that went down over Egypt's Sinai Peninsula killing all 224 people on board. Egypt has now accepted a request from the United States to assist with the investigation. A source with knowledge of the investigation says the NTSB, the National Transportation Safety Board here in the United States, will dispatch a team once it has details on when and where the plane's engines will be examined. Those engines are U.S. made. Meanwhile, U.S. intelligence officials think the most likely scenario is that jihadi terrorists planted a timer with a bomb, likely made of C4. That word from U.S. officials familiar with the investigation. With us now from New York, our CNN terrorism analyst Paul Cruikshank, and the former ATF executive Matthew Horace. Paul, the C4, that's a military grade explosive. Certainly powerful enough to bring down a plane. But how easy is it to obtain?</s>PAUL CRUICKSHANK, CNN TERRORISM ANALYST: Well, we know that the group that has claimed responsibility, the ISIS affiliate in Sinai, has stockpiled a large quantity of C4 explosive. They've also used the C4 explosive in attacks this year. So it would certainly be consistent with ISIS in Sinai actually carrying out this attack, managing to recruit an insider at the airport. I think it points away from a lone wolf type of scenario because it would be difficult for an individual without connections to an established terrorist outfit to obtain this military grade explosive, Wolf.
Russian Plane Crash Mystery; U.S. Investigators Invited To Egypt.