Terrorism -- 21 Terrorism 16 Prevention 6 Foreign relations -- 5 National security -- 4 United States 4 Al Qaeda 3 more ... International offenses 3 International relations 3 War on terrorism, 2001- 3 Foreign relations 2 Insurgency 2 Iraq 2 National security 2 Security Management 2 Security, International 2 September 11 Terrorist Attacks, 2001 2 Weapons of mass destruction 2 Afghanistan 1 Anti-Americanism 1 Case studies 1 Civil security -- 1 Democracy -- 1 Destraction 1 Economic conditions 1 Economic development 1 Fundamentalism 1 Government publicity 1 Hijaking of ships 1 Homeland security 1 less ...