Terrorism September 11 Terrorist Attacks, 2001 27 Prevention 17 History 16 War on terrorism, 2001- 15 Foreign relations 14 Government policy 13 United States 12 Politics and government 11 Biography 9 Islam 8 Religious aspects 8 Qaida (Organization) 7 Terrorists 6 Jihad 5 Intelligence service 4 Juvenile literature 4 National security 4 World politics 4 Atrocities 3 Bin Laden, Osama, 1957- 3 International relations 3 Islamic fundamentalism 3 Psychological aspects 3 Saudi Arabia 3 Terrorist 3 War on Terrorism, 2001- 3 Afghanistan 2 Arab 2 Communism 2