Military intercept procedures have been in effect for decades, but in this post-9/11 era, pilots have had to become more familiar with these procedures so they'll know what to do just in case they accidentally violate sensitive airspace.
Now there is an addition to be aware of: flares.
Flares can be used as another way to alert the pilot of the aircraft that is being intercepted. The use of flares during a military intercept is explained in Section 5-6-2 of the Aeronautical Information Manual: "If the U.S. military intercepts an aircraft and flares are dispensed in the area of that aircraft, aviators will pay strict attention, contact air traffic control immediately on the local frequency or on VHF guard 121.5 or UHF 243.0, and follow the intercept's visual ICAO signals. Be advised that noncompliance may result in the use of force."
May 11, 2006