Terrorism -- Prevention. -- 21 Government policy -- 14 Foreign relations -- 11 National security -- 11 Prevention -- 11 War on Terrorism, 2001-2009 11 more ... Islam 8 Religious aspects -- 8 Politics and government -- 7 Terrorism 7 Prevention 6 Security measures 5 September 11 Terrorist Attacks, 2001 5 Civil defense -- 4 History -- 4 Islamic fundamentalism -- 4 Politics and government 4 Aeronautics, Commercial -- 3 Civil rights -- 3 Intelligence service -- 3 Islamic fundamentalism 3 Jihad 3 Psychological aspects 3 Security measures -- 3 Terrorists -- 3 Economic sanctions, American 2 Emergency management -- 2 Evaluation. -- 2 Hijacking of aircraft -- 2 less ...