Prevention Terrorism 4 Terrorism -- 3 Hijacking of aircraft 2 Hijacking of aircraft -- 2 Security measures 2 Aeronautics, Commercial -- 1 more ... Airports -- 1 Child terrorists 1 Culture conflict -- 1 Drug abuse 1 Drug abuse -- 1 Ethnic relations 1 Government policy -- 1 Hostage negotiations 1 Narcotics, Control of 1 Non-governmental organizations 1 Nuclear industry -- 1 Nuclear nonproliferation -- 1 Nuclear terrorism -- 1 Popular works 1 Security measures -- 1 Social conflict -- 1 Sports injuries -- 1 Sports medicine -- 1 Substance abuse 1 less ...