“With respect, there have been — and the Ababziar matter would be one I would refer to that’s currently being adjudicated in the criminal courts — from time to time, and we are constantly working against different and evolving threats involving various terrorist groups and various ways they may seek to enter the country.”
http://www.theblaze.com/stories/janet-napolitano-says-members-of-terrorist-groups-enter-u-s-from-mexico-from-time-to-time/