Terrorism -- September 11 Terrorist Attacks, 2001 6 Government policy -- 5 War on terrorism, 2001- 4 War on Terrorism, 2001-2009 3 Intelligence service -- 2 Islam 2 more ... Jihad 2 National security -- 2 Prevention. -- 2 Religious aspects -- 2 Terrorists 2 Anti-Americanism 1 Evaluation. -- 1 Forecasting. -- 1 Foreign relations -- 1 Governmental investigations -- 1 Hijacking of aircraft -- 1 Islamic fundamentalism 1 Nuclear terrorism -- 1 Political violence -- 1 less ...