Hard to know what to believe, since Russia has been caught several times the past year selling arms to terrorist groups, I wouldn't think terrorists would do anything to anger their parts source, but with terrorists who knows? Since one witness stated the blast seemed to center around the dining car....hmmm, can you say propane leak?? We'll probably never know. Just hope that putting the words terrorists and trains together doesn't mean new security measures here to keep pesky railfans at bay.