in strength. cnn has learned recent intercepts of messages from senior al qaeda operatives in yemen are renewing concern the group is planning new attacks. the intercepts don't indicate specific targets but are described by one source as, quote, active plotting. >> there are multiple indications that al qaeda in the arabian peninsula is plotting attacks, both within yemen against u.s. and other western structures as well as overseas. >> reporter: the group is yemen well known for the failed underwear bomber attempt to bring down an airplane christmas day 2009. four years later, the u.s. intelligence community believes it poses the greatest threat of an attack on the u.s. >> they are still capable of conducting attacks outside of yemen, including plotting attacks against the united