"Changing World"

Obama's got a new ad highlighting that he understands the challenges America faces in today's world.

EARLIER TODAY "Senator Obama joined a experts on nuclear non-proliferation, bio security and cyber security, as well as Indiana Senator Evan Bayh and former Georgia Senator Sam Nunn at Purdue University in West Lafayette, Indiana to discuss security issues in a changing world. Following his opening remarks, the panel spent over an hour discussing the dangers of what the 9/11 Commission called our 'failure of imagination,' and the need to stay one step ahead of the threats of the 21st century."