
Wolf Blitzer asks Peter Bergen & Walter Isaacson if our national security is at risk in wake of the Colorado shooting.
Wolf Blitzer asks former Rep. Jane Harman and former Homeland Security secretary Michael Chertoff about the future of homeland security and the biggest threats to the U.S.
A potential hit list targeting individuals in U.S. government, industry and the media is posted on jihadi Web forums. CNN's Jeanne Meserve reports.

