Terrorism 481 Prevention 191 Religious aspects 80 Islam 76 History 37 National security 36 Government policy 32 Islamic fundamentalism 32 Jihad 30 Security measures 29 September 11 Terrorist Attacks, 2001 27 War on Terrorism, 2001- 24 English fiction 23 United States 23 Social aspects 22 Terrorists 22 Islam and politics 18 Nuclear terrorism 16 Fiction 15 Foreign relations 15 War on Terrorism, 2001-2009 15 Economic aspects 14 Psychological aspects 14 Intelligence officers 13 Politics and government 13 Civil defense 12 Emergency management 12 Violence 12 Computer security 11 Finance 11