Terrorism -- 32 September 11 Terrorist Attacks, 2001 8 Terrorism 6 Foreign relations -- 5 Prevention. -- 4 War on Terrorism, 2001-2009 4 Islam 3 more ... Religious aspects -- 3 Terrorists 3 Terrorists -- 3 War on terrorism, 2001- 3 Emergency management -- 2 International relations 2 Islamic fundamentalism 2 National security -- 2 Politics and government -- 2 Psychological aspects 2 Radicalism -- 2 Security, International 2 Weapons of mass destruction 2 Anti-Americanism 1 Biological warfare 1 Bioterrorism 1 Chemical warfare 1 Church and state -- 1 Citizen participation. -- 1 Civil rights -- 1 Computer network resources -- 1 Criminology 1 Democracy -- 1 less ...