Terrorism -- National security -- 4 United States 4 Prevention 3 Foreign relations -- 2 International relations 2 Security Management 2 more ... War on terrorism, 2001- 2 Civil security -- 1 Economic development 1 Foreign relations 1 Homeland security 1 Infrastructure -- 1 International offenses 1 Military policy 1 National security 1 Political stability 1 Responses -- 1 Safety measures 1 Security 1 Security measures 1 Security strategy 1 Security, International 1 September 11 Terrorist Attacks, 2001 1 Transportation -- 1 Weapons of mass destruction 1 less ...