Houston Chronicle 
Tuesday, Oct 6th, 2009
The North American defense operation known as NORAD — once known mostly as a chief component of ballistic missile defense — will be conducting exercises over South Texas skies today reflective of its new responsibility to protect American and Canadian skies from potential terrorists.
A NORAD spokesman urged people not to worry if they see a pair of fighter jets flying at low altitudes close to a civilian plane. It’s just an interception test.
“You may see two F-16s off the wings of a civilian aircraft,” said spokesman Lt. Desmond James. “Potentially this could be concerning to people on the ground. If they see or hear this going on, don’t be alarmed. You don’t have to call 911.”
After the Sept. 11 attacks, NORAD’s mission changed to include the interception of unidentified civilian aircraft in the U.S. and Canada.