Terrorism Prevention 27 History 17 Religious aspects 15 Islam 14 Terrorists 13 Government policy 11 War on terrorism, 2001- 10 September 11 Terrorist Attacks, 2001 9 Foreign relations 8 Case studies 6 Political violence 6 Guerrilla warfare 5 Islamic fundamentalism 5 Politics and government 5 Qaida (Organization) 5 Violence 5 Weapons of mass destruction 5 World politics 5 Democracy 4 Guerrillas 4 Military policy 4 National security 4 Police 4 Psychology 4 Addresses, essays, lectures 3 Biography 3 Congresses 3 Counterinsurgency 3 Fanaticism 3