Nearly ten years after the 9/11 attacks, President Obama says the nation's biggest terrorist concern isn't a big operation launched from overseas, but from a single person on U.S. soil. 

FOX News Radio's Rich Johnson reports from Washington DC:

Homeland Security Secretary Janet Napolitano commented on the President's concerns at an event on Wednesday.  It was all part of an announcement on the expansion of the "See Something, Say Something" Ad campaign.

Watch the Public Service Announcement VIDEO:

Listen to Secretary Napolitano's comments HERE: