Terrorism -- Prevention. -- 20 War on Terrorism, 2001-2009 11 Foreign relations -- 10 Government policy -- 10 National security -- 10 Prevention -- 9 more ... Politics and government -- 7 Islam 6 Prevention 6 Religious aspects -- 6 Terrorism 6 Security measures 5 September 11 Terrorist Attacks, 2001 5 Civil defense -- 4 History -- 4 Aeronautics, Commercial -- 3 Civil rights -- 3 Intelligence service -- 3 Islamic fundamentalism 3 Islamic fundamentalism -- 3 Psychological aspects 3 Security measures -- 3 Emergency management -- 2 Evaluation. -- 2 Hijacking of aircraft -- 2 Internal security -- 2 Islam and politics -- 2 Jihad 2 Political aspects -- 2 less ...