While Fighter Pilots made movies, SAM Officers made History. (U-2 over Sverdlovsk, B-52's over Hanoi, F-4 Phantoms over the Sinai, F-16's and the F-117A Stealth bomber over the Balkans.)
This looks like a classic solid fuel rocket booster failure. My guess would be cracking of the fuel because of ageing and/or improper storage. These things are getting pretty old now.