confident that it was a bomb that took down the jetliner taking off from sharm el sheikh. one official telling cnn it is quote 99.9% certain. egypt is walking a fine line of the reports of lax security at the airports, but requesting russia officials to conduct security checks. joining us with latest is cnn's ian lee from sharm el sheikh. >> reporter: good morning, alison. we are hearing from the u.s. law enforcement official that the fbi may be requested to come in and help the egyptian officials in the investigation in particular listening to a noise that occurs right at the last second of the plane flight. a loud bang is heard on the voice recorder. u.s. and u.k. officials believe this is an explosion from a