aware of indicates terrorist groups continue to target commercial aviation and are aggressive in pursuing innovative methods to undertake their attacks to include smuggling an explosive device in various consumer objects. >> reporter: officials have told cnn there was credible and specific intelligence that isis would try to attack aviation assets and a hint from a top u.s. commander about why the accelerated effort on the ground in syria against the group. >> there's an imperative to get isolation in place around raqqah because our intelligence feeds tell us that there is a significant external operations attacks planning. >> reporter: al qaeda's affiliate in yemen, aqap, has for years been actively trying to target commercial airliners destined for the u.s. looking for ways to create bombs